Clinical Nuclear Medicine

Published by Lippincott, Williams & Wilkins
Print ISSN: 0363-9762
Publications
Two indium-111 labeled anti-melanoma murine monoclonal antibodies (MAb), 96.5 and ZME-018, each recognizing separate antigens on melanoma cells, were administered intravenously to 17 patients with melanoma in a sequential fashion to determine whether: 1) additional tumor sites could be imaged with the combination compared to a single Mab; 2) the first MAb influenced the biodistribution and tumor localization of the second; and 3) significantly toxicity occurred with the combination. Patients were randomized to receive either 96.5, followed by ZME-018, ZME-018 followed by 96.5, or each MAb followed by itself (controls). Infusions of the second MAb occurred 10 days after the first infusion. Gamma camera images were obtained 72 hours after each antibody infusion. There were 139 known metastatic sites of which 72 lesions were localized by either MAb for an overall sensitivity of 52%. The detection rate was higher when lesions only greater than 1.5 cm were considered. Imaging results were independent of MAb administration sequence. When ZME-018 was given as the first infusion, when ZME-018 was given as a second infusion (p = NS). However, mean sensitivities using 96.5 as the first or second infusion were 48% and 66% respectively (p = NS). There was not a significant number of sites detected by MAb 2 that were missed by MAb 1. Human anti-murine antibody (HAMA) response occurred in seven of eight patients studied; two patients who experienced toxicity had levels of HAMA greater than 2000 ng/ml. We conclude that the use of these two murine anti-melanoma monoclonal antibodies given in sequential fashion did not significantly change the imaging sensitivity from that seen with each individual antibody. Moreover, with the exception of one patient, mean plasma half-life of the MAb did not change significantly, suggesting that overall clearance mechanisms were not saturated by the consecutive doses of monoclonal antibody or significantly altered by the presence of HAMA.
 
A patient whose huge lung mass was demonstrated as a large defect on I-123 N,N,N'trimethyl-N'[2-hydroxy-3-methyl-5-iodobenzyl]-1,3-propanediamine (HIPDM) lung imaging is presented. I-123 HIPDM, a lipophilic agent, is designed for early detection of abnormal cerebral perfusion. Since up to 50% of the administered agent is accumulated and perhaps metabolized in the lung, the radiopharmaceutical may be potentially useful for detection of pathology of the lung in addition to evaluation of pulmonary amine metabolism.
 
The aim of this retrospective study was to investigate the clinical impact of F-FDG PET in patients with advanced lung adenocarcinoma stratified according to the epidermal growth factor receptor (EGFR) mutation status. A total of 56 patients with advanced lung adenocarcinoma were included in the study. Thirty-one patients (55%) were EGFR mutation-positive, whereas the remaining 25 (45%) participants tested negative for EGFR mutations. All of the patients underwent F-FDG PET/CT for pretreatment planning. The main outcome measure was overall survival (OS) at 24 months. The following F-FDG PET/CT-derived variables were tested for their associations with OS: main tumor SUVmax, main tumor total lesion glycolysis, and target lesions TLG determined per RECIST (Response Evaluation Criteria In Solid Tumors) 1.1 criteria (TLGRECIST). We also investigated the clinical characteristics in relation to OS and EGFR mutation status. In EGFR mutation-positive patients, neither the clinical characteristics nor F-FDG PET/CT-derived parameters were significantly associated with OS. In contrast, univariate analysis identified male sex, a positive history of smoking, and TLGRECIST greater than or equal to 412 g as adverse prognostic factors for OS in EGFR mutation-negative patients. After adjustment for potential confounders in multivariate analysis, TLGRECIST was the sole independent predictor of OS in this subgroup. TLG determined per RECIST 1.1 criteria is an independent predictor of OS in EGFR mutation-negative patients with advanced lung adenocarcinoma. Further studies are needed to investigate whether this parameter may be a promising tool for stratifying such patients for risk-adapted therapies.
 
Detection of recurrent colorectal carcinoma can be a diagnostic challenge. The authors report a case of a patient who, after resection of his primary colorectal carcinoma, had a recurrence that was not detected by MRI or serial CT examination, but was clearly demonstrated by In-111 labeled CYT-103 scintigraphy. This case demonstrates the use of CYT-103 scintigraphy in detecting recurrent colorectal cancer in a patient, despite results of nondiagnostic MRI or serial CT examinations.
 
In-111 satumomab whole-body imaging is used in the evaluation of patients with colorectal carcinoma. The authors report a case of false-positive In-111 localization in a nonfunctional adrenal adenoma in a patient with metastatic colon carcinoma.
 
An immunoconjugate of the whole antibody, B72.3, has been approved by the FDA. It is labeled with indium-111, which allows imaging studies intended for the diagnosis and staging of colorectal and recurrent ovarian carcinoma. The new diagnostic imaging agent (CYT-103), Oncoscint CR/OV, has found particular use in evaluating patients with recurrent carcinoma. The three major indications for the study are: 1) occult disease--unexplained rise in serum tumor markers (e.g. CEA), with negative work-up including CT; 2) known local recurrence (e.g. liver or rectal area)--surgery is planned, but there is a need to rule out other areas of involvement; 3) clarify equivocal CT or MRI finding--to distinguish whether an abnormality is due to recurrent tumor or scar tissue, fibrosis, or unopacified bowel loop. Oncoscint has proven to be more sensitive than CT in the detection of disease in the pelvis and extrahepatic abdomen. CT remains the modality of choice for the detection of liver metastases. The combined sensitivity of the two modalities is 88% on a per-patient basis.
 
A 65-year-old man with prostate cancer underwent a bone scan for evaluation of metastatic disease and left second and third metatarsal fractures using 15.89 mCi Tc-99m MDP. He was status post insertion of one hundred thirteen 0.97-mCi prostatic TheraSeed palladium-103 implants (110 mCi). Although 20 to 23 keV characteristic radiographs are the most significant in terms of treatment dose, higher-energy gamma emissions of low abundance (297 keV = 0.011%, 362 keV = 0.060%, 498 keV = 0.011%) are responsible for scatter seen in the pelvis on a Tc-99m MDP bone scan. Because the palladium-103 half-life is 16.97 days, this interference will persist for weeks after seed implantation.
 
Fifteen presurgical patients with a history of ovarian carcinoma were evaluated with immunoscintigraphy using the In-111-labeled monoclonal antibody conjugate CYT-103. Twelve of these patients had residual neoplasia at time of laparotomy. A single intravenous dose of the radiolabeled monoclonal antibody was given to these patients before restaging laparotomy. All patients also underwent CT scanning of the abdomen and pelvis before laparotomy. Immunoscintigraphy detected the presence of disease in 10 of 12 patients before surgery, whereas CT scanning detected disease in only 6 of these 12 women. The results of this study indicate that immunoscintigraphy using In-111 CYT-103 is more sensitive than CT and may add useful information to the preoperative evaluation of women with ovarian carcinoma.
 
A retrospective review of 4023 thyroid scans performed at the Royal Adelaide Hospital in the five years to February 1987 identified 105 cases of subacute thyroiditis. Subacute thyroiditis accounted for 9.9% of subjects scanned for hyperthyroidism. Eighty-four percent had painful thyroiditis, 6% postpartum thyroiditis, and 10% painless thyroiditis. Follow-up was obtained in 68% of cases, and 11% were taking thyroxine, probably indicating long-term hypothyroidism. Apart from the presence of antibodies in post-partum thyroiditis, no other factor was identified which predicted the development of long-term hypothyroidism. As subacute thyroiditis is a common cause of hyperthyroidism in our community, the authors believe all people with hyperthyroidism should have a thyroid scan unless they have distinctive features of Graves' disease.
 
A 31-year-old woman presenting with tonic seizures was radiologically investigated using CT, MR imaging, and positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) and C-11 methionine (MET). Initial CT, C-11 MET PET, and F-18 FDG PET suggested a low-grade tumor such as oligodendroglial tumor. However, MR imaging findings strongly suggested venous infarction. We chose observation rather than surgical intervention. Two months later, self-regression of the lesion confirmed the diagnosis of venous infarction. Therefore, to avoid unnecessary invasive operations, we should keep in mind that high C-11 MET accumulation does not always signify a tumoral lesion but is sometimes the result of vascular pathology.
 
The integrated modality positron emission tomography/computed tomography (PET/CT) with C-11 choline is an established diagnostic tool for restaging prostate cancer patients with a biochemical failure after primary treatment. Thymoma is a rare tumor originating in thymus epithelial cells, asymptomatic in one-third to one-half of patients, and often occurring in the fourth and fifth decades of life. In the present case, C-11 choline PET/CT was performed in a prostate cancer patient with a biochemical relapse, to restage the disease. In addition to the detection of local recurrent disease in prostatic fossa, an abnormal C-11 choline increased uptake in mediastinum was reported. The mediastinal finding was initially wrongly interpreted by clinicians as a lymph nodal metastasis from prostate cancer. However, histopathological analysis confirmed the presence of a thymoma. Although rare, thymoma has to be considered as differential diagnosis in case of mediastinal masses presenting C-11 choline PET/CT positive findings, to avoid inappropriate patient management.
 
To investigate the potential of C-11 choline PET/CT imaging for differentiating prostate cancer (PCa) from benign prostate hyperplasia (BPH). Forty-nine patients with prostate lesions underwent C-11 choline PET/CT imaging that was performed 5 minutes after injection of 7.4 MBq/kg (0.2 mCi/kg C-11 choline in the supine position over 2 bed positions (3 minutes per position), covering the pelvis, and the whole body (6 bed) when necessary. After attenuation correction, PET data were analyzed visually and semiquantitatively by measuring maximum standardized uptake value (SUVmax) of the prostate lesions (target) and the muscles (nontarget) and calculating their ratios (P/M). Twenty-one PCa and 28 BPH lesions were proven histologically. The mean values of the SUVmax of PCa and BPH were 7.87 +/- 5.74 and 4.95 +/- 5.14, respectively without a significant difference between these 2 groups (t = 2.02; P > 0.05). The mean P/M of PCa and BPH were 4.21 +/- 1.61 and 1.87 +/- 0.98. The statistical difference of P/M between them was significant (t = 2.04; P < 0.01). Using 2.3 (P/M) as the criterion, C-11 choline PET/CT imaging showed a sensitivity of 90.48%, a specificity of 85.71%, and a negative predictive value of 92.31%. PET/CT precise localization of the hot spot in different parts of the prostate could contribute to the diagnosis. C-11 choline PET/CT is a valuable noninvasive imaging technology in the diagnosis of PCa. The parameter P/M could differentiate PCa from benign lesions better than SUV.
 
Bone scintigraphy has been used extensively in prostate cancer patients to detect bone involvement.C-choline PET/CT is indicated when a biochemical recurrence is suspected, as this procedure is able to detect local recurrence, lymph-node infiltration, and metastases.In cases where the results of these 2 procedures do not coincide, MRI is then usually performed. F-fluoride may become an alternative to MRI for bone imaging.In our patient series, all bone lesions with C-choline uptake were metastases. F-Fluoride did not increase specificity of C-choline but increased sensitivity of bone scintigraphy. CT helped in the interpretation of osteoarthritis and trauma lesions.
 
Positron emission tomography combined with computed tomography (PET/CT) using C-11- or F-18-labeled choline as a radiotracer is increasingly used for the evaluation of prostate cancer. Distinguishing between manifestations of prostate cancer and unrelated uptake can be difficult. We report a patient with prostate cancer and an incidental finding of a paraganglioma with high C-11 choline uptake. Therefore, neuroendocrine tumors should be considered in the differential diagnosis in patients with focal choline uptake. The diagnostic value of choline positron emission tomography combined with computed tomography for the evaluation of neuroendocrine tumors is, however, limited due to the high physiological uptake in liver, spleen, pancreas, and the gastrointestinal tract.
 
With the availability of multiple positron emission tomography (PET) tracers for neurooncology, there is a need to define the appropriate tracer in a given clinical setting, and it is in this regard that we undertook this study to directly compare F-18 flurodeoxyglucose (FDG) PET and C-11 methionine (MET) PET for the evaluation of recurrence in primary brain tumors. Thirty-seven patients with a history of treated primary brain tumors referred for evaluation of recurrent disease were initially included in the study. Two patients had to be excluded because of insufficient follow-up. There were 23 males and 12 females, mean age: 33.7 ± 16.4 years; range: 5 to 65 years. All patients underwent the MET and FDG study on the same day. Visual image interpretation was performed independently by 2 PET physicians for each tracer using the plain PET and fused PET/CT images; the FDG images were evaluated first. Images were analyzed semiquantitatively using tumor to normal contralateral cortex ratios (T/N). Each patient was followed up for a minimum of 18 months. Imaging results were compared with histopathology on tumor excision or biopsy in 14 patients and with clinical follow-up and MRI/MRS at the end of 18 months in 21 patients. The final diagnosis was tumor recurrence in 24 patients and no recurrence/stable disease in 11 patients. On FDG, findings in 15/35 (42%) were suggestive of recurrent tumors. On MET, findings in 24/34 (70.5%) cases were suggestive of recurrent tumors. Spatially separated secondary lesions including intraventricular deposits were clearly delineated in 5 cases, 3 were glioblastoma multiforme (GBM) and 2 were anaplastic astrocytomas. One of the secondary lesions was missed on FDG PET. Using a cutoff for T/N ratio on FDG of >0.75 to differentiate recurrence from no recurrence, sensitivity of FDG was 81.2% (confidence interval [CI] = 54.4%-96%), whereas specificity was 88.9% (CI = 51.8%-99.7%). Area under the curve was 0.819 (CI = 0.615-0.943), P = 0.0003. Using a cutoff for T/N ratio of >1.9 to differentiate recurrence from no recurrence, sensitivity of MET was 94.7% (CI = 74.0%-99.9%), whereas specificity was 88.89% (CI = 51.8%-99.7%). Area under the curve was 0.942 (CI = 0.785-0.995), P < 0.0001. Interobserver agreement, κ coefficient, for MET was 0.93, suggesting good interobserver agreement, whereas for FDG, it was fair (0.23). MET should be the radiotracer of choice in the evaluation of recurrence of primary brain tumors because the sensitivity for detection and delineation of the possible recurrent tumor, as well as secondary deposits, is higher with MET. MET-PET is an easier technique to interpret, irrespective of the glioma grade, with less interobserver variability and straightforward localization of tumorous accumulation.
 
A 58-year-old woman with breast carcinoma, after mastectomy, radiotherapy, and chemotherapy, underwent a whole-body F-18 FDG PET/CT for restaging, which revealed multiple skeletal metastasis. Hypometabolism was noted in the right frontal lobe. The patient subsequently underwent a C-11 methionine brain scan, which demonstrated multiple dural-based metastatic foci confirmed on contrast-enhanced MR. FDG PET has limitations in brain tumor detection. Amino acid tracers are particularly attractive for imaging of brain tumors because of relatively high tumor to brain activity ratios.
 
A case of cerebellopontine angle (CPA) schwannoma is reported with F-18 fluorodeoxyglucose (F-18 FDG) PET and C-11 acetate PET findings. A 10-year-old patient with a CPA schwannoma had a continuous headache after the tumor removal. Follow-up brain MRI showed tumor recurrence in the left occipital lobe, and F-18 FDG PET images revealed low FDG accumulation in the recurrent mass lesion. However, C-11 acetate PET images showed focally increased C-11 acetate accumulation in the same lesion. This case illustrates the characteristic F-18 FDG PET and C-11 acetate PET findings of a recurrent CPA schwannoma.
 
A 69-year-old man with no history of neurologic or psychiatric disorders underwent C-PiB PET as a healthy volunteer for amyloid imaging study. C-PiB PET images demonstrated an unexpected increased PiB binding in the left frontal region. MR images demonstrated an extra-axial left frontal mass lesion with mild enhancement, highly suggestive of meningioma. There is a limited amount of published information on the detection of meningioma with C-PiB PET.
 
We present a first study of the use of 11C-acetate (ACET) positron emission tomography (PET)/computed tomography (CT) in bladder urothelial carcinoma (UC) and an intraindividual comparison with 11C-choline (CHOL) PET/CT. Fourteen patients with biopsy-proven UC (11 T2, 3 T1 refractory to treatment) were prospectively evaluated before radical cystectomy and excision of pelvic lymph nodes (LNs), with ACET and CHOL PET/CT scans performed within 1 week. Image acquisition started 5 minutes after intravenous injection of 12 to 14 mCi for both tracers. Standardized uptake values (SUVs) and tumor-to-background ratios (TBR) were calculated for all tumor and nodal findings and correlated with histopathology and follow-up. ACET and CHOL were taken up in all UCs, involved LNs, and prostate pathology. SUVs were on average slightly, nonsignificantly higher for CHOL uptake (SUV) in UCs and significantly higher for ACET in LNs. TBR was nonsignificantly higher with CHOL for UC and significantly higher for LNs. In this preliminary series, 11C-ACET and 11C-CHOL PET/CT showed equivalent results in the preoperative evaluation of UC. Both tracers have the potential to contribute to selecting patients who would benefit from combined treatment--neoadjuvant chemotherapy and surgery--by identifying pathologic LNs or from surgery only, thanks to their high negative predictive value for LN involvement.
 
Eight patients with proven or suspected neoplastic lesions were examined with 1-aminocyclobutane C-11-carboxylic acid and 1-aminocyclopentane C-11-carboxylic acid using positron emission computed tomography. The results of this comparative study have shown that both of these unnatural amino acids have a high affinity for malignant tumors. The potential of nonmetabolizable C-11-labeled amino acids as noninvasive indicators of metabolic tumor activity is demonstrated and discussed.
 
C-11 acetate positron emission tomography (PET) is known to have high sensitivity in detecting hepatocellular carcinoma. However, one of the shortcomings of C-11 acetate PET in the diagnosis of hepatocellular carcinoma is that C-11 acetate also accumulates in focal nodular hyperplasia, which makes it challenging to distinguish hepatocellular carcinoma form focal nodular hyperplasia when a conventional single time point PET imaging method is used. Two patients with suspected hepatocellular carcinoma and negative fluoro-deoxy-glucose PET scans underwent C-11 acetate PET dual time imaging in which both early and delayed images were acquired. One patient was subsequently confirmed having hepatocellular carcinoma while the other had focal nodular hyperplasia. C-11 acetate imaging was positive in both patients. Interestingly, in hepatocellular carcinoma the C-11 acetate activity in the delayed images is higher than in the early images while in focal nodular hyperplasia, the C-11 acetate activity decreased in the delayed image when compared with early images. Our findings suggest that dual time point imaging has potential to improve the diagnostic accuracy of C-11 acetate PET in the diagnosis of hepatocellular carcinoma.
 
We introduce the case of a 70-years-old man with an elevated level of prostate-specific antigen and prior negative biopsy. For targeting rebiopsy, the patient underwent C-choline PET/CT and subsequent PET/MR. Both the high uptake in PET and the abnormal findings in MR gave strong evidence for prostate cancer at the ventral periphery of the right apex. This location is sometimes not covered by routine sextant biopsy. The following targeted rebiopsy was positive for prostate cancer. This case indicates the potential role of PET/MR for identifying primary prostate cancer because of its high soft tissue contrast and the possibility of a multimodality approach.
 
The aim of our study was to examine the usefulness of PET with C-methionine (MET) and F-fluorodeoxyglucose (FDG) in the differentiation of glioblastoma multiforme (GBM) and intracranial diffuse large B-cell lymphoma (DLBCL). We evaluated 22 patients retrospectively with an enhancing brain tumor on MRI, including 15 GBM and 7 DLBCL, which was confirmed by histopathology. Dynamic PET scans with MET and FDG were performed for preoperative differential diagnosis. We assessed the images qualitatively and quantitatively. In quantitative assessment, the SUVmax was used on FDG PET and both late and early phases on MET PET. In addition, the ratio of SUVmax in the late and early phases on MET-PET was evaluated (ΔSUVmax). SUVmax on FDG PET of DLBCL was significantly higher than that of GBM. Setting an SUVmax of 12.0 as the cutoff for differentiating DLBCL from GBM, 1 GBM and 1 DLBCL were found to be false-positive and false-negative, respectively.SUVmax in the late and early phases of MET-PET was not significantly different between DLBCL and GBM; however, we also found significant differences in ΔSUVmax on MET-PET. Using ΔSUVmax 1.17 as the cutoff, we could differentiate DLBCL from GBM completely. In the present study, ΔSUVmax on MET-PET was slightly superior to SUVmax on FDG PET. Both SUVmax on FDG PET and ΔSUVmax on MET-PET were considered to be good diagnostic tests when encountering difficulties in this differential diagnosis.
 
Although uptake of F-18 FDG is well documented in granulomatous disease, there is little literature available regarding C-11 methionine positron emission tomography (PET) in these conditions. We present a case in which C-11 methionine imaging was performed for localization of a probable parathyroid adenoma, but other areas of uptake identified were subsequently found to be the result of sarcoidosis. Clinicians must therefore take care when interpreting C-11 methionine PET scans because granulomatous disease could cause false-positives.
 
Positron emission tomography/computed tomography (PET/CT) with C-11 choline is currently used for restaging prostate cancer in patients with biochemical failure. Skeletal Paget disease can be associated with prostate cancer, and bone scintigraphy can differentiate the 2 conditions. We report the case of a 74-year-old patient with prostate cancer who displayed multiple areas skeletal uptake of C-11 choline on a restaging PET/CT, which was attributed to both metastatic and pagetic bone diseases. The pattern of C-11 choline uptake was different between the 2 conditions, probably in relation to the different mechanisms of disease. The possibility of C-11 choline uptake in pagetic bone should be kept in mind when interpreting PET/CT findings in patients with prostate cancer.
 
We assessed the usefulness of F-18 fluorodeoxyglucose positron emission tomography (FDG PET) and C-11 acetate PET (AC PET) in distinguishing hepatic lesions due to consequential disease (hepatocellular adenoma and malignant lesions) from focal nodular hyperplasia (FNH) in patients at low risk of malignancy. Thirty-one patients with 43 lesions were prospectively enrolled. The diagnostic work-up included Doppler and contrast-enhanced ultrasonography, contrast-enhanced computed tomography, and/or magnetic resonance imaging. Fine needle biopsy was performed if the imaging study was inconclusive. The work-up revealed 36 FNH and 7 consequential lesions (5 hepatocellular adenoma, 1 hepatoma, and 1 metastasis). All patients underwent FDG and AC PET. FDG PET with target/background ratio (T/Br) greater than 1.2 and AC PET with T/Br of less than 1.2 were considered positive test for consequential disease. On FDG PET, we had 6 true-positive out of 7 lesions due to consequential diseases, with a sensitivity of 85.7%, and 33 true-negative out of 36 lesions with FNH, with a specificity of 91.7%. Using AC PET, there were 2 true-positive lesions out of 7 caused by neoplasms, with a sensitivity of 28.6%, and 34 true-negative lesions out of 36 FNH, with a specificity of 94.4%. When the goal is differentiating FNH from liver neoplasms, AC PET offered no additional diagnostic advantage over what is achieved with FDG PET.
 
A 64-year-old woman with previous thyroid surgery developed symptomatic primary hyperparathyroidism, requiring hydration and furosemide. Cervical ultrasonography and an MRI of the neck were inconclusive. Early Tc-99m-methoxyisobutylisonitrile images 15 minutes post injection demonstrated focal uptake in the left lower thyroid lobe consistent with a small thyroid adenoma. Neither subtraction or late planar nor Tc-99m-methoxyisobutylisonitrile-SPECT images identified a focal area of increased uptake. PET/CT with 460 MBq C-11-methionine demonstrated a focal area of increased uptake in the right thyroid bed. Subsequent surgery confirmed a parathyroid adenoma of 1.4 cm in diameter. Histopathologic analysis showed a parathyroid adenoma of chief-cell type.
 
PET imaging with C-11 methionine and F-18 FDG were performed on a 75-year-old man with recurrence of a glioblastoma in the left parietal region. Markedly increased methionine and slightly increased F-18 FDG uptake were seen in another lesion in the right parietal region which was a meningioma.
 
Although the optimum treatment of primary central nervous system lymphoma (PCNSL) remains a challenge, there is increasing interest in methotrexate-based chemotherapy as an effective strategy. Here, we report evidence supporting the utility of methionine PET/CT for evaluating PCNSL disease extent and response to high-dose methotrexate therapy. Four patients newly diagnosed with diffuse large B-cell PCNSL underwent methionine PET/CT and MRI of the brain at baseline and again after completion of high-dose methotrexate combination chemotherapy. Three patients also received pretreatment FDG PET/CT, and the intervals between MRI and both PET/CTs were within 3 weeks. The results of methionine PET/CT were compared with MRI and clinical findings. Pretreatment methionine PET/CT demonstrated clear demarcation of PCNSL tumors with high contrast in 3 patients and only faint uptake in the remaining patient, which also showed low FDG uptake. In 1 patient, methionine PET/CT displayed more tumor lesions than FDG PET/CT did. After high-dose methotrexate chemotherapy, methionine images displayed complete disappearance of abnormal uptake in all 4 patients. In 3 of the patients, posttreatment MRI and clinical follow-up corroborated findings of complete remission. In the remaining patient, MRI showed nonenhancing T2 hyperintensities in the periventricular white matter, for which the significance was inconclusive. Methionine PET/CT may provide clinically useful information complementary to MRI for monitoring the response to systemic chemotherapy in patients with PCNSL.
 
A 35-year-old man presented with right lower extremity numbness and weakness. CT demonstrated an irregular left parietal hypoattenuation with a punctuate calcification. MRI revealed a T1 low signal and T2 high signal lesion with extensive surrounding edema. Gadolinium-enhanced MRI showed an irregular enhancing lesion. F-FDG and C-methionine PET both demonstrated high uptake in the left parietal lesion. Lesion SUV was 7.5 for F-FDG and 3.0 for C-methionine. Surgical pathology demonstrated cerebral sparganosis.
 
F-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET)/computed tomography (CT) alone has limited sensitivity for the diagnosis of hepatocellular carcinoma (HCC). We hoped to improve the diagnostic sensitivity by combining F-18 FDG and C-choline PET/CT. A total of 76 consecutive patients with HCC were prospectively enrolled. Whole-body F-18 FDG PET/CT scan was performed for all patients. In those patients with negative F-18 FDG scans, a regional C-choline PET/CT scan was also performed. Positive F-18 FDG scans were noted in 61.1% (48/76) patients with HCC. Increased F-18 FDG uptake correlated with decreased tumor differentiation (P = 0.042). In 28 HCC patients with negative F-18 FDG scans, C-choline scan was positive in 71.4% patients. C-choline scan did not detect any significant difference between well- and moderately differentiated HCC (P = 0.585). Compared with F-18 FDG scan, C-choline scan showed a trend toward an improved detection of well-differentiated HCC (66.7% vs. 35.7%, NS). For detection of moderately differentiated HCC, the sensitivity of C-choline and F-18 FDG PET/CT was similar (85.7% vs. 72.0%, P = 0.648). The dual-tracer modality improved the diagnostic sensitivity of F-18 FDG PET/CT alone from 63.1% to 89.5% (P < 0.001). F-18 FDG in conjunction with C-choline increases the sensitivity of PET/CT in detecting HCC.
 
Renal uptake of Tl-201 reflects renal perfusion and may have a role in defining renal asymmetry in patients with hypertension who are referred for myocardial scintigraphy. The authors compared two methods of quantitating differential renal uptake of Tl-201, with similar data obtained from the angiographic and renal uptake (RU) phases of Tc-99m DTPA scintigraphy in 35 patients with hypertension. For Tl-201, asymmetry in renal counts was quantitated based on a simple outline technique or on interpolative background subtraction of 5-minute posterior images. Inter-observer and intra-observer variability among duplicate measurements were lower for Tl-201, particularly with interpolative background subtraction, than for Tc-99m DTPA. Renal/background ratios were similar for Tl-201 and RU-phase Tc-99m DTPA images when considering liver, spleen, or inter-renal regions as background; however, paraspinal uptake was relatively higher with Tl-201 (P less than 0.01). Qualitatively, renal asymmetry scores with the two radiotracers agreed (r = 0.89, blinded readings by four observers), although asymmetry was more marked with Tl-201 (P = 0.06). Measurements with Tl-201 agreed with both phases of Tc-99m DTPA (r = 0.96 to 0.98), but interpolative background subtraction systematically yielded greater inter-renal asymmetry than RU (P less than 0.01), reflecting the qualitative impression. Thus, ancillary Tl-201 imaging reflects differences between the kidneys in a fashion similar but not identical to Tc-99m DTPA scintigraphy.
 
PET scanning of the brain with F-18 FDG and C-11 methionine (MET) is useful for characterizing brain lesions discovered at MRI or CT. Most positive PET scans indicate malignancy. However, this case report demonstrates positive F-18 FDG and C-11 MET PET scans in a patient with a nonmalignant condition, neurosarcoidosis. We detail the history and evaluation of a 59-year-old woman who presented with ataxia. The patient's evaluation included a contrast-enhanced MRI followed by PET scanning of the brain with C-11 MET and of the brain and trunk with F-18 FDG. The patient subsequently underwent biopsy of a lesion as directed by MRI and PET. The MRI demonstrated multiple enhancing leptomeningeal lesions consistent with metastatic disease. PET with F-18 FDG and C-11 MET demonstrated lesions in both cerebellar hemispheres with F-18 FDG accumulation in the mediastinum and left hilum. Biopsy of a brain lesion directed by MRI and PET revealed sarcoidosis. In evaluating brain lesions, PET with F-18 FDG and C-11 MET can help localize the lesion best suited for biopsy. However, not all lesions that have increased uptake on C-11 MET or F-18 FDG PET are malignant. Granulomatous inflammatory diseases such as neurosarcoidosis should also be considered in the differential diagnosis.
 
We report a case of a 75-year-old male patient treated with radiotherapy in 1999 for prostate cancer. Due to a rise in prostate-specific antigen, he underwent C-choline PET/CT. The study was negative for secondary lesions but revealed an incidental pathologic focal brain uptake. A subsequent magnetic resonance examination confirmed the presence of a brain lesion typical for meningioma.
 
The aim of the study was the comparison of C-11 methionine (MET) and C-11 choline (CHO) in the positron emission tomography (PET) imaging of brain metastases in correlation to the histopathology findings in stereotactic biopsy. In all, 8 patients underwent MET and CHO PET and magnetic resonance imaging, in 7 of these, the metastases were previously treated by radiation therapy. Histopathologic diagnosis was made for each patient by frame-based stereotactic serial biopsy. Standardized uptake values of tumor uptake and lesion-to-normal brain tissue ratios (LNRs) of the lesions were determined. LNRs for each tracer were compared with the histopathology findings and follow-up. In 6 patients, biopsy revealed viable metastases, 1 patient suffered from tumor recurrence in follow-up and 1 patient was tumor free in biopsy and follow-up. In the last mentioned patient, LNR was the lowest determined in all patients for CHO, but not for MET. Mean standardized uptake values of the lesions were in median 1.8 for MET and 1.1 for CHO, median LNRs were 1.5 for MET and 6.6 for CHO. LNRs for CHO were significant higher than those for MET (P = 0.007). In the direct comparison to the well-established amino acid tracer MET, CHO seems to be promising for the imaging of brain metastases because of significantly higher LNRs in tumor tissue compared with MET without evidence for a lower specificity of CHO uptake.
 
We report the case of a 75-year-old woman with dual primary subclavicular angiosarcoma and lung cancer. FDG PET showed enhanced uptake (SUVmax 12.2) in the subclavicular lesion and equivocal uptake (SUVmax 3.8) in the lung lesion. C-11 acetate (AC) PET showed equivocal uptakes in both with SUVmax values of 1.56 and 1.1, respectively. Incisional biopsy of the subclavicular mass and video-assisted thoracoscopic surgery were performed, as we considered the 2 lesions to be unrelated malignant tumors based on the findings of FDG-PET and AC-PET. Finally, the 2 lesions were diagnosed as subclavicular angiosarcoma and lung cancer.
 
Positron emission tomography/computed tomography (PET/CT) with C-11 choline has been used for staging, restaging, and follow-up of various tumors, whereas its role for imaging meningiomas has only been preliminarily explored. The aim of this study was to compare C-11 choline and F-18 fluorodeoxyglucose (F-18 FDG) uptake in meningiomas and relate these findings to the histopathological analysis. Two sequential three-dimensional PET/CT scans with 370 MBq (10 mCi) of C-11 choline and 370 MBq (10 mCi) of F-18 FDG were performed 2 hours apart in 7 patients with histologically confirmed meningiomas. Five patients had WHO grade I and 2 had WHO grade II meningioma. For each scan, two-dimensional regions of interest were drawn on tumor boundaries and on the contralateral side on CT images and copied to the corresponding PET images. SUVmax and tumor-to-background ratio were calculated. Relative to the contralateral side, C-11 choline uptake was increased in all meningiomas, whereas F-18 FDG uptake was decreased in 6 patients and increased in 1 of the 2 patients with grade II meningiomas. In the whole group, SUVmax of C-11 choline and F-18 FDG were 3.6 +/- 1.3 and 5.7 +/- 1.3, respectively. The tumor-to-background ratio for C-11 choline was much higher than that for F-18 FDG (5.3 +/- 0.8 vs. 0.9 +/- 0.2, respectively) (P < 0.001). The uptake of C-11 choline was higher in patients with grade II than in grade I meningiomas. These preliminary results suggest that C-11 choline may better image meningiomas in comparison with F-18 FDG. Clinical applications of C-11 choline PET/CT for grading and follow-up of meningiomas need to be assessed in further studies.
 
A 28-year-old man with headache, nausea, and decreased vision had a left parieto-occipital tumor demonstrated by MRI. Postradical resection and histology showed a solid mass containing rhabdoid cells, 10% positive for Ki-67. After completing chemotherapy and radiotherapy treatment, follow-up MRI revealed possible tumoral recurrence. Cerebral F-18 FDG PET revealed no pathologic uptake, and C-11 methionine PET showed a pathologic low uptake. These findings suggested recurrence of a mild-grade aggressiveness tumor, which was confirmed by a second neurosurgical resection.
 
An accessory lobe of the liver is a rare congenital anomaly, which is very difficult to diagnose preoperatively. Hepatocellular carcinoma in an accessory lobe of the liver is much rarer. We report here our findings of hepatocellular carcinoma in an accessory left lobe on C-acetate PET/CT images in a 67-year-old man who had both an unremarkable diagnostic contrast abdominal CT and a negative FDG PET/CT scan before the C-acetate PET/CT study.
 
A 32-year-old woman presented with a 2-month history of intermittent amnesia and episodes of syncope. A brain MRI indicated that the patient had either a low-grade glioma or encephalitis. A dual tracer PET/CT scan with both C-11 acetate and FDG was performed to further assess the nature of the brain abnormality. The CT images revealed a low-density lesion in the left hippocampus, which had intense FDG uptake, but was not C-11 acetate-avid. Based on the imaging results, encephalitis was considered the most likely diagnosis. The patient recovered completely following the therapy tailored to encephalitis.
 
Alpha-aminoisobutyric acid (AIB), a synthetic, nonmetabolized amino acid which is rapidly transported into viable cells by the A-type or alanine-preferring amino acid transport system, has been labeled with the short-lived, positron-emitting radionuclide carbon-11. Carbon-11 labeled AIB is currently being evaluated as a tumor imaging agent for in vivo amino acid transport studies in patients with cancer. In this study, C-11 AIB was used to image two patients with malignant fibrous histiocytoma (MFH), a pleomorphic sarcoma. Following intravenous administration of C-11 AIB, tumors in the distal femur of one patient and in the anterior chest wall of another patient were well visualized using high energy gamma scintigraphy. Since therapy may alter the accumulation of amino acids in tumor tissue, studies using C-11 AIB in patients with MFH before and after chemotherapy are in progress.
 
The aim of this study was to apply positron emission tomography (PET) with C-8-dicyclopropylmethyl-1-methyl-3-propylxanthine (MPDX), a radioligand for adenosine A1 receptor (A1R), to patients with hemianopia caused by brain injury to study neurorepair mechanisms in the brain. Four patients with homonymous hemianopia and 15 healthy subjects were examined using PET to measure cerebral glucose metabolism, C-flumazenil (FMZ) binding to the central benzodiazepine receptor, and MPDX binding to A1R. Left and right regions of interest (ROIs) were selected, and semiquantitative data on the 3 kinds of PET examinations were obtained. The ROIs were referenced using the data for homologous regions in the contralateral hemisphere [ipsilateral/contralateral (I/C) ratio]. The I/C ratios for cerebral glucose metabolism and FMZ binding were low in the primary visual cortex (PVC) and visual association cortex in all the patients, whereas MPDX binding increased in the PVC in patients 1 and 2. Patients 1 and 2 experienced improvement in their visual field after 1 year. However, the other 2 patients showed no changes. We observed an increase in MPDX binding to A1R in the injured portion of the PVC in the patients who recovered. Evaluation of A1R by MPDX-PET may be useful for predicting prognosis and understanding the compensatory and reorganization processes in hemianopia caused by organic brain damage.
 
A 53-year-old man who presented with mild headache and ophthalmodynia underwent carbon-11 methionine (MET) positron emission tomography (PET). MET PET images demonstrated intense uptake in the periphery of the brain, significantly higher than the physiological uptake in the brain. Biopsy specimens from the pachymeninx indicated hypertrophic pachymeningitis with IgG4-positive plasma cells. After steroid therapy, he became asymptomatic, and a follow-up PET scan showed disappearance of the peripheral brain uptake of MET.
 
We previously showed that prostate-specific antigen (PSA) doubling time (PSADT) is a significant predictor of 11C choline positron emission tomography/computed tomography (PET/CT) findings in prostate cancer (PCa) patients. This study compared PSA velocity (PSAV) and PSADT to predict 11C choline PET/CT findings. PSAV and PSADT were retrospectively calculated in 170 PCa patients with biochemical failure after radical prostatectomy, who underwent 11C choline PET/CT for restaging of disease. Median PSA was 1.25 ng/mL (range: 0.23-48.6 ng/mL), and median PSAV was 0.99 ng/mL/y (range: 0.11-98.9 ng/mL/y). Patients with positive 11C choline PET/CT (n = 75) had significantly (P < 0.05) higher PSAV than patients with negative 11C choline PET/CT (n = 95) (6.93 ± 13.08 vs. 1.23 ± 2.03 ng/mL/y). The percent of patients with positive 11C choline PET/CT was 21% for PSAV <1 ng/mL/y, 56% for PSAV between 1 and 2 ng/mL/y, and 76% for PSAV >2 ng/mL/y. The quality of fitting (r2) of PSA values according to the exponential function (PSADT) was significantly (P < 0.05) better than the quality of fitting according to the linear function (PSAV) in the entire sample and in all anatomic regions. At multivariate analysis, trigger PSA, PSADT but not PSAV obtained the statistical significance (P < 0.05). PSAV can be used to stratify the risk of positive 11C choline PET/CT in PCa patients with biochemical failure. Patients with PSAV >1 ng/mL/y should be selected to increase the positive detection rate of 11C choline PET/CT. The greater statistical power of PSADT compared with PSAV could be related to the better capability of fitting time-dependent changes in PSA values, thereby better reflecting the natural growth of recurrent PCa.
 
Abnormal uptake of Tl-201 chloride in the liver along with correlative radiologic imaging is presented in an unusual case of an 11-year-old boy with a small 2.1 cm hepatocellular carcinoma. Although planar Tl-201 images were normal, triple-headed SPECT Tl-201 images showed a focal area of increased liver activity at the site of the tumor which corresponded to a photopenic area on Tc-99m SC SPECT images. The patient successfully underwent partial liver resection of a pathologically proven hepatocellular carcinoma.
 
Positron emission tomography/computed tomography (PET/CT) with 11C-choline is an established diagnostic tool for restaging prostate cancer patients with biochemical failure after primary treatment. In the present case, 11C-choline PET/CT was performed in a prostate cancer patient with skeletal metastases, treated with hormonal therapy. In addition to the detection of pathologic uptake at prostate and vertebra, 11C-choline uptake occurred in the neck. The finding was suggestive for a parathyroid adenoma on subsequent ultrasound, then finally confirmed by parathyroid scintigraphy and histopathological analysis performed after hemithyroidectomy.
 
A 19-year-old woman was hospitalized for a head injury resulting from an automobile accident. The radiographic computed tomographic (CT) scan showed a skull fracture, and magnetic resonance imaging (MRI) revealed a soft tissue signal intensity mass in her right temporal region, suggesting the possibility of cerebrospinal fluid (CSF) leak. For this reason, In-111 cisternography was performed to clarify the presence of the CSF leak. In addition, dual-isotope SPECT with In-111 DTPA and Tc-99m HMDP was performed. These images clearly located a CSF leak at the patient's right mastoid. Dual-isotope SPECT with In-111 DTPA and Tc-99m HMDP was useful for detecting and locating the CSF leak.
 
A case is reported in which a labeled white cell scan was helpful in the diagnosis of a periappendiceal abscess. The method of labeling is described and the usefulness of the technique discussed.
 
When septicemia has failed to resolve after appropriate antibiotic therapy, labeled leukocyte scintigraphy is often valuable to locate focal sites of infection. In this case, probable infection of a left ventricular aneurysm, the sequela of an old myocardial infarction, was demonstrated. Massive splenomegaly due to portal vein stenosis after prior orthotopic liver transplantation also was depicted. In previously reported cases of infected left ventricular aneurysms, there usually has been prior myocardial infarction. As in this case, associated mural thrombus and false aneurysms have been reported. Demonstration by labeled leukocyte scintigraphy has not been previously reported.
 
Top-cited authors
Abass Alavi
  • University of Pennsylvania
Hongming Zhuang
  • The Children's Hospital of Philadelphia
Rakesh Kumar
  • All India Institute of Medical Sciences
Hussein M Abdel-Dayem
  • New York Medical College
Doemnico Rubello