Assessment of radiofrequency ablation of lung metastasis from colorectal cancer using dual time-point PET/CT.
ABSTRACT A 70-year-old man with operated colorectal cancer relapsed with a solitary lung metastasis. Dual time-point PET/CT performed at 60' (standard images) and after 2 hours (delayed images) showed focal uptake in the lung nodule. A second uptake in the liver dome was also visualized only in the delayed images. Radiofrequency of the lung metastasis was performed by CT-fluoroscopy guide. A PET/CT 1 month after radiofrequency showed significant reduction of activity in the delayed images, and the uptake at 3 months was virtually normal. A fine-needle biopsy of the liver lesion confirmed the final diagnosis of metastasis from adenocarcinoma.
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ABSTRACT: The aim of this study was to investigate the difference in the rates of FDG uptake between malignant and inflammatory cells and processes. In vitro studies: (18)F-FDG uptake by different tumor cell lines (human mesothelioma [REN]; rat mesothelioma [II45]; mice melanoma [B18F10]; mice mesothelioma [AB12]; human myeloma [GM1500]; and human ovarian cancer [SKOV3]) and peripheral blood mononuclear cells isolated from 8 healthy human volunteers was measured 20 and 60 min after FDG was added into growth medium. Animal studies: II45 cells were implanted into the left flank of rats (n = 5) and a focal inflammatory reaction (mechanical irritation) was generated in the right flank. PET images at 45 and 90 min after injection of FDG were obtained and standardized uptake values (SUVs) were determined. Patient studies: Seventy-six patients who had dual time FDG PET scans were retrospectively analyzed. All results were expressed as the percentage change in SUV of the later time image from that of the earlier time (mean +/- SD). In vitro studies: Except for the SKOV3 cell line, which had only minimally increased FDG uptake (+10% +/- 26%; P > 0.3), all other tumor cell lines tested showed significantly increased FDG uptake over time (GM1500, +59% +/- 19%; B18F10, +81% +/- 15%; AB12, 93% +/- 21%; II45, +161% +/- 21%; REN, +198% +/- 48%; P < 0.01 for all). By contrast, FDG uptake in mononuclear cells was decreased in 7 of 8 donors. Animal studies: SUVs of tumors from 90-min images were significantly higher than those from 45-min images (+18% +/- 8%; P < 0.01), whereas the SUVs of inflammatory lesions decreased over time (-17% +/- 13% of the early images; P < 0.05). Clinical studies: The SUVs of delayed images from the known malignant lesions compared with those of earlier scans increased over time (+19.18% +/- 9.58%; n = 31; P < 0.001; 95% confidence interval, 15.8%-22.6%). By contrast, the SUVs of benign lung nodules decreased slightly over time (-6.3% +/- 8.1%; n = 12; P < 0.05; 95% confidence interval, -10.9% to -1.7%). The SUV of inflammatory lesions caused by radiation therapy (+1.16% +/- 7.23%; n = 8; P > 0.05; 95% confidence interval, -3.9%-6.2%) and the lesions of painful lower limb prostheses (+4.03% +/- 11.32%; n = 25; P > 0.05; 95% confidence interval, -0.4%-8.5%) remained stable over time. These preliminary data show that dual time imaging appears to be useful in distinguishing malignant from benign lesions. Further research is necessary to confirm these results.Journal of Nuclear Medicine 09/2001; 42(9):1412-7. · 5.77 Impact Factor
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ABSTRACT: 18F-FDG PET has reached widespread application in the assessment of pulmonary nodules. This study compares the diagnostic accuracy of standard 18F-FDG PET scanning with those of dual time point 18F-FDG PET scanning. Thirty-six patients (21 women, 15 men; mean age, 67 y; range, 36-88 y) with 38 known or suspected malignant pulmonary nodules underwent PET of the thorax at 2 time points: scan 1 at 70 min (range, 56-110 min) and scan 2 at 123 min (range, 100-163 min) after the intravenous injection of 2.5 MBq 18F-FDG per kilogram of body weight. All scanning was performed on a dedicated C-PET scanner. The mean interval between the scans was 56 min (range, 49-64 min). Regions of interest were overlaid onto each fully corrected image in the areas of the radiographically known lung densities. The standardized uptake values (SUVs) were calculated for both time points. Surgical pathology and follow-up revealed 19 patients with 20 malignant tumors, whereas 16 patients had benign lesions. The tumor SUVs (mean +/- SD) were 3.66 +/- 1.95 (scan 1) and 4.43 +/- 2.43 (scan 2) (20.5% +/- 8.1% increase; P < 0.01). Four of 20 malignant tumors had SUVs of <2.5 on scan 1 (range, 1.12-1.69). Benign lesions had SUVs of 1.14 +/- 0.64 (scan 1) and 1.11 +/- 0.70 (scan 2) (P = not significant). Standard PET scanning (single time point) with a threshold SUV of 2.5 (at time point 1) reached a sensitivity of 80% and a specificity of 94%; dual time point scanning with a threshold value of 10% increase between scan 1 and scan 2 reached a sensitivity of 100% with a specificity of 89%. Dual time point 18F-FDG PET results in a very high sensitivity and specificity for detection of malignant lung tumors.Journal of Nuclear Medicine 07/2002; 43(7):871-5. · 5.77 Impact Factor
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ABSTRACT: Radiofrequency thermal ablation (RFA) is an emerging technique in the treatment of focal hepatic tumors. Magnetic resonance imaging (MRI) and computed tomography (CT) are currently used to monitor hepatic tumors after RFA for residual disease and recurrence. Fluorodeoxyglucose (FDG) positron emission tomography (PET) is an excellent imaging method for the detection of liver metastases, but it has not been thoroughly evaluated as an alternative to anatomic imaging in the surveillance of liver tumors treated with RFA. The purpose of this investigation was to determine the role of FDG-PET imaging in the surveillance of liver tumors treated with RFA. Thirteen patients with histories of malignant tumors of the liver treated with RFA and who had received post-treatment FDG-PET scans were assessed retrospectively. One patient had two post-RFA FDG-PET scans, eight patients had concurrent MRI scans, and six patients had concurrent CT scans. Imaging findings were compared with the results of clinical follow-up. There were either recurrent tumors at the ablation site (8 patients) or new metastases (3 patients) in 11 patients. FDG-PET identified all 11 cases and did not misidentify any cases. Of the seven patients with positive PET findings who received an MRI scan, three were also positive on MRI (42.9%); the other four cases were either negative or equivocal. Of the four patients with positive PET findings who received a CT scan, only two had positive CT scan findings (50%). All recurrences diagnosed by PET were confirmed on clinical follow-up. In this preliminary study, FDG-PET was superior to anatomic imaging in the surveillance of patients treated with RFA for malignant hepatic tumors.Clinical Nuclear Medicine 04/2003; 28(3):192-7. · 2.96 Impact Factor