Peter Kovacs

University of Innsbruck, Innsbruck, Tyrol, Austria

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Publications (52)114.41 Total impact

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    ABSTRACT: Purpose: Radiofrequency ablation (RFA) has become widely accepted as the first-line local tumor therapy of surgical untreatable primary and secondary liver malignancies. Main risk factors for residual tumor and local recurrence are tumor size (> 3cm), imprecise probe placement and insufficient overlapping of multiple ablation spheres. Our aim was to evaluate if stereotactic RFA may improve the results of conventional techniques. Materials/Methods: Stereotactic RFA of 92 primary and 67 secondary liver tumors in 68 patients was performed. After general anesthesia the patient was rigidly immobilized on the CT table. A contrast-enhanced helical CT scan (2 mm slice thickness) was obtained with respiratory triggering. Pathways for multiple probes were planned on a navigation system in order to cover the whole tumor volume by overlapping necroses. Depending on the size of the tumor (0.5-11 cm, mean: 2.9 cm) pathways for the placement of 1-24 probes were planned. After registration a targeting device was adjusted for every path. In maximal expiration one after another coaxial needle was advanced to the preplanned depth. A native control CT was performed for verification of needle placement. RFA followed subsequently. Residual tumor was determined on a contrast-enhanced CT after 1 month, recurrence on CTs at 3 months intervals (mean follow-up: 9.2 months). Results: Residual tumor was found in 12/159 lesions (2.7%) of which 10 could be successfully retreated. Recurrences were found in 12/147 (8.2%) lesions, of which 3 were successfully re-ablated. Recurrence rate for lesions < 3 cm (n=92) was 4.3%, 3-5 cm (n=48) was 12.5% and > 5 cm (n=19) was 10.5%. Conclusion: Stereotaxy allows for precise positioning and 3D-distribution of RFA probes in order to achieve an overlapping ablation zone for even large lesions. It decreases the local tumor recurrence rate as compared to conventional CT/US-guided RFA. Keywordsnavigation-stereotaxy-tumor therapy-treatment-ablation-radiofrequency-virtual planning
    01/2010: pages 83-86;
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    ABSTRACT: Computed tomography (CT) together with 99mTc-sestamibi single photon emission computed tomography (MIBI-SPECT) image fusion (CT-MIBI-SPECT image fusion) allows virtual exploration of the neck. The aim of this study was to evaluate whether CT-MIBI-SPECT image fusion is superior to MIBI-SPECT and CT in detecting abnormal parathyroid glands in patients with primary hyperparathyroidism. CT-MIBI-SPECT image fusion for preoperative localization was performed in 116 patients with primary hyperparathyroidism (pHPT). Both investigations were performed with reproducible fixation of the patient on a vacuum mattress. At a special work station the neck was virtually explored by viewing the CT images in all 3 dimensions. The MIBI-SPECT images were superimposed on underlying CT images. Only patients with single-gland disease were evaluated (pHPT: 112, persistent pHPT: 1, recurrent pHPT: 1, persistent secondary hyperparathyroidism: 1, tertiary HPT after kidney transplantation: 1). CT-MIBI-SPECT image fusion results were compared with those obtained with CT alone and MIBI-SPECT alone. The predicted positions were correlated with the intraoperative findings. CT-MIBI-SPECT image fusion was able to predict the exact position of the abnormal gland in 102 (88%) of the 116 patients, whereas CT alone showed in 75 (65%) patients and MIBI-SPECT alone in 64 (55%) patients the exact position of the abnormal gland. Sixty-two patients underwent minimally invasive surgery, namely in 21 patients with a unilaterally focused approach and in 33 patients with a bilateral approach (27 of these underwent simultaneous thyroid resection). Sensitivity for CT-MIBI-SPECT image fusion was 88%, for CT alone 70%, and for MIBI-SPECT alone 59%. Specificity for CT-MIBI-SPECT image fusion was 99%, for MIBI-SPECT alone 95%, for CT alone 94%. Overall accuracy for CT-MIBI-SPECT image fusion was 97%, for CT alone 89%, for MIBI-SPECT 87%. This study provides evidence that CT-MIBI-SPECT image fusion is superior to CT or MIBI-SPECT alone for preoperative localization of enlarged parathyroid glands in patients with single-gland primary hyperparathyroidism.
    Annals of surgery 10/2009; 250(5):761-5. · 7.19 Impact Factor
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    ABSTRACT: (68)Ga-labeled 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-d-Phe(1)-Tyr(3)-octreotide (DOTA-TOC) PET has proven its usefulness in the diagnosis of patients with neuroendocrine tumors. Radionuclide therapy ((90)Y-DOTA-TOC or (177)Lu-DOTA-octreotate) is a choice of treatment that also requires an accurate diagnostic modality for early evaluation of treatment response. Our study compared (68)Ga-DOTA-TOC PET with CT or MRI using the Response Evaluation Criteria in Solid Tumors. Furthermore, standardized uptake values (SUVs) were calculated and compared with treatment outcome. Forty-six patients (29 men, 17 women; age range, 34-84 y) with advanced neuroendocrine tumors were investigated before and after 2-7 cycles of radionuclide therapy. Long-acting somatostatin analogs were not applied for at least 6 wk preceding the follow-up. Data were acquired with a dedicated PET scanner. Emission image sets were acquired at 90-100 min after injection. (68)Ga-DOTA-TOC PET images were visually interpreted by 2 experienced nuclear medicine physicians. For comparison, multislice helical CT scans and 1.5-T MRI scans were obtained. Attenuation-corrected PET images were used to determine SUVs. Repeated CT evaluation and other imaging modalities, for example, (18)F-FDG, were used as the reference standard. According to the reference standard, (68)Ga-DOTA-TOC PET and CT showed a concordant result in 32 patients (70%). In the remaining 14 patients (30%), discrepancies were observed, with a final outcome of progressive disease in 9 patients and remission in 5 patients. (68)Ga-DOTA-TOC PET was correct in 10 patients (21.7%), including 5 patients with progressive disease. In these patients, metastatic spread was detected with the follow-up whole-body PET but was missed when concomitant CT was used. On the other hand, CT confirmed small pulmonary metastases not detected on (68)Ga-DOTA-TOC in 1 patient and progressive liver disease not detected on (68)Ga-DOTA-TOC in 3 patients. Quantitative SUV analysis of individual tumor lesions showed a large range of variability. (68)Ga-DOTA-TOC PET shows no advantage over conventional anatomic imaging for assessing response to therapy when all CT information obtained during follow-up is compared. Only the development of new metastases during therapy was detected earlier in some cases when whole-body PET was used. SUV analysis of individual lesions is of no additional value in predicting individual responses to therapy.
    Journal of Nuclear Medicine 09/2009; 50(9):1427-34. · 5.56 Impact Factor
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    ABSTRACT: To perform focused or minimally invasive surgery for hyperparathyroidism (HPT) exact preoperative localization is mandatory. Computed tomography-(99m)Tc-sestamibi-single photon emission computed tomography image fusion (CT-MIBI-SPECT) serves this difficult task in single gland HPT to a large extent. The aim of this study was to evaluate whether CT-MIBI-SPECT image fusion is superior to MIBI-SPECT alone and CT alone in detecting abnormal parathyroid tissue in patients with multiglandular disease. CT-MIBI-SPECT image fusion for preoperative localization was performed in 30 patients with multiglandular disease. There were six patients with primary hyperparathyroidism (four MEN I syndromes and two double adenomas; one of these patients has HRPT2 gene mutation), 14 with secondary, and eight with tertiary HPT, further one patient each suffering from persistent primary and persistent secondary hyperparathyroidism. In both persistent patients only one remaining gland was left from primary surgery. The results of MIBI-SPECT, CT, and CT-MIBI-SPECT image fusion were compared in these patients. The outcome and the exact predicted positions were correlated with intraoperative findings. In five out of six patients with multiglandular primary hyperparathyroidism more than one gland was detected, thus multiglandular disease could be suspected preoperatively. Overall CT-MIBI-SPECT image fusion was able to predict the exact position of all abnormal glands per patient in 14 of 30 (46.7%) cases, whereas CT alone was successful in 11 (36.7%), and MIBI-SPECT alone just in four (13.3%) of 30 patients. Multiglandular disease in primary hyperparathyroidism can be suspected preoperatively in a high percentage of patients. Additionally, this study shows that CT-MIBI-SPECT image fusion is superior to CT or MIBI-SPECT alone in preoperative localization of all pathologic glands in patients suffering from multiglandular disease.
    Langenbeck s Archives of Surgery 09/2009; 395(1):73-80. · 1.89 Impact Factor
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    ABSTRACT: Aiming devices enable the use of neuronavigation systems for rigid instrument guidance mimicking the possibilities of a frame-based system without having a stereotactic frame affixed to the skull. The aim of the presented work was to investigate the phantom targeting accuracy of the Vertek aiming device (Medtronic Inc., Louisville, USA) and whether it can be safely and accurately applied in a concept of minimally invasive brain biopsy in which multi-modal image fusion, image-to-patient registration and head immobilization were based on a non-invasive vacuum mouthpiece. A plastic model of a head with 20 target beads broadly distributed around the head volume was used for determination of CT-based targeting accuracy. Every target was punctured 5 times totaling 100 needle positionings. Accuracy was evaluated on postoperative CT scans with the needles in place. The mean normal deviation (n = 100) was 1.5 +/- 0.8 mm and the mean angle of deviation was 1.1 +/- 0.7 degrees. In a preliminary clinical series in ten patients diagnostic biopsy sampling of intracranial lesions with a median diameter of 28 mm (range: 12-90 mm) could be achieved in all patients and no biopsy related complications were recorded. The experimental results showed a similar accuracy to frame-based stereotaxy. The device facilitates trajectory alignment via two pivot joints and the actual depth and location of the biopsy needle can be monitored. Within the limitations of a preliminary study, brain biopsy may be accurately and safely performed for lesions > or = 12 mm.
    min - Minimally Invasive Neurosurgery 01/2009; 51(6):361-9. · 1.14 Impact Factor
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    ABSTRACT: To determine the accuracy of frameless stereotactic computed tomographic (CT)-guided wire placement for percutaneous fixation of posterior pelvic ring fractures in human cadavers. Four intact human cadavers were fixated in a double-vacuum immobilization system. A 2.5-mm helical CT dataset was obtained and transferred to the three-dimensional (3D) navigation system. In every specimen, two paths on each side (total number, 16) were defined on multiplanar reconstructions of the 3D CT datasets, simulating fixation of the iliosacral joint. An aiming device was adjusted according to the plan, and a 2.5-mm pin was advanced through the aiming device to the precalculated target point. To determine the accuracy of pin placement, a control CT scan was co-registered to the planning CT scan (with the planned trajectories). The distance between the planned and achieved positions of the pins (3D accuracy) was calculated in millimeters. The mean 3D accuracy was 1.84 mm +/- 0.9 (standard deviation) at the bone entrance point and 2.5 mm +/- 1.2 at the target, as determined with image fusion between the planning CT scan and the control CT scan with the pins in place. The described technique enables accurate placement of pins in the pelvis and may be useful for percutaneous orthopedic procedures.
    Journal of Vascular and Interventional Radiology 08/2008; 19(7):1093-8. · 2.15 Impact Factor
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    ABSTRACT: In surgery for primary hyperparathyroidism, preoperative localization together with intraoperative parathyroid hormone assay is important when minimal invasive operations of the parathyroid glands are intended. In cases of reoperation, correct localization of the abnormal parathyroid glands is extremely instrumental. Computed tomography (CT)-(99m)Tc-sestamibi (MIBI)-single photon emission computed tomography (SPECT) image fusion allows for a virtual exploration of the neck by showing the suspected gland three-dimensionally with all the anatomic landmarks in correct position. The aim of this study was to evaluate whether CT-MIBI-SPECT image fusion is superior to MIBI-SPECT alone in detecting abnormal parathyroid glands in patients with previous neck surgery. In a prospective study, CT-MIBI-SPECT image fusion for preoperative localization was performed in 28 patients with hyperparathyroidism and previous neck surgery. Twenty-one patients had thyroidectomy and seven patients had surgery for hyperparathyroidism. The results of MIBI-SPECT alone and CT-MIBI-SPECT image fusion were compared in these patients. The outcome and the exact predicted position, not just the predicted side, were correlated with intraoperative findings. CT-MIBI-SPECT image fusion was able to predict the exact position of the abnormal gland in 24 of 28 patients (86%), whereas MIBI-SPECT alone was successful in 12 of 28 cases (43%, p < 0.004) only. CT-MIBI-SPECT image fusion detected all three pathologic glands in their ectopic position. With MIBI-SPECT alone, just one ectopic pathologic gland was found. This study provides evidence that CT-MIBI-SPECT image fusion is superior to MIBI-SPECT alone in preoperative localization of enlarged parathyroid glands in patients with hyperparathyroidism and previous neck surgery. This should be kept in mind if the results are compared to earlier studies concerning CT-MIBI-SPECT image fusion.
    Langenbeck s Archives of Surgery 07/2008; 393(5):687-92. · 1.89 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate the diagnostic value of a new somatostatin analog, (68)Ga-labeled 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-d-Phe(1)-Tyr(3)-octreotide ((68)Ga-DOTA-TOC), for PET in patients with known or suspected neuroendocrine tumors. PET was compared with conventional scintigraphy and dedicated CT. Eighty-four patients (48 men, 36 women; age range, 28-79 y; mean age +/- SD, 58.2 +/- 12.2 y) were prospectively studied. For analysis, patients were divided into 3 groups: detection of unknown primary tumor in the presence of clinical or biochemical suspicion of neuroendocrine malignancy (n = 13 patients), initial tumor staging (n = 36 patients), and follow-up after therapy (n = 35 patients). Each patient received 100-150 MBq (68)Ga-DOTA-TOC. Imaging results of PET were compared with (99m)Tc-labeled hydrazinonicotinyl-Tyr(3)-octreotide ((99m)Tc-HYNIC-TOC) and (111)In-DOTA-TOC. CT was also performed on every patient using a multidetector scanner. Each imaging modality was interpreted separately by observers who were unaware of imaging findings before comparison with PET. The gold standard for defining true-positive (TP), true-negative (TN), false-positive (FP), and false-negative (FN) results was based on all available histologic, imaging, and follow-up findings. PET was TP in 69 patients, TN in 12 patients, FP in 1 patient, and FN in 2 patients, indicating a sensitivity of 97%, a specificity of 92%, and an accuracy of 96%. The FP finding was caused by enhanced tracer accumulation in the pancreatic head, and the FN results were obtained in patients with a tumor of the gastrointestinal tract displaying liver metastases. (68)Ga-DOTA-TOC showed higher diagnostic efficacy compared with SPECT (TP in 37 patients, TN in 12 patients, FP in 1 patient, and FN in 34 patients) and diagnostic CT (TP in 41 patients, TN in 12 patients, FP in 5 patients, and FN in 26 patients). This difference was of statistical significance (P < 0.001). However, the combined use of PET and CT showed the highest overall accuracy. (68)Ga-DOTA-TOC PET shows a significantly higher detection rate compared with conventional somatostatin receptor scintigraphy and diagnostic CT with clinical impact in a considerable number of patients.
    Journal of Nuclear Medicine 04/2007; 48(4):508-18. · 5.56 Impact Factor
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    ABSTRACT: PURPOSE The success of radiofrequency ablation (RFA) depends on precise placement and distribution of the electrodes in the tumor. We developed and evaluated a novel method for computer-assisted liver tumor puncture for RFA in 25 patients in 28 sessions (51 HCCs, 3 CCCs; 140 electrodes). METHOD AND MATERIALS After oral intubation and rigid immobilization a 2,5 mm contrast-enhanced helical CT scan was obtained in maximal expiration. Depending on the size of the tumor (range, 0,5 - 8,5 cm; median size: 2,5 cm) pathways for the placement of 1-9 radiofrequency electrodes were planned on the Treon navigation system (Medtronic Inc., USA). 14 sessions were performed with the multipolar Celon RF device (Olympus), 14 sessions with the unipolar Cooltip device (Tyco), respectively. After sterile draping the Atlas aiming device (Medical Intelligence, Schwabmünchen, Germany) was adjusted using the navigation system. In maximal expiration the electrodes were advanced through the targeting device to the predefined depth. A fusion of the control CT (with electrodes in place) with the planning CT (with the planned paths) allowed for a precise measurement of the accuracy of the puncture. When optimal distribution of the electrodes was confirmed, percutaneous RFA was performed. 1 patient (1 lesions) had to be retreated in a second RFA-session. Follow-up CT-scans were performed within 1 month after the intervention and afterwards in a 3 month-interval. RESULTS The mean duration from the planning CT to the verification CT was 40 minutes. Follow-up contrast enhanced control-CTs (median time of follow-up : 7,0 months) revealed recurrences in 3/54 lesions (5,6%) and 2/24 patients (8,3%). CONCLUSION The novel method based on stereotactic navigation allows for a precise planning and performance of the ablation procedure. The evaluation of this novel RFA technique shows that even large liver tumors can be successfully ablated. CLINICAL RELEVANCE/APPLICATION When treating large liver tumors precise placement and distribution of electrodes which is essential to cover the whole tumor volume can be achieved with stereotactic navigation.
    Radiological Society of North America 2006 Scientific Assembly and Annual Meeting; 11/2006
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    ABSTRACT: Ablative neurosurgical treatment of trigeminal neuralgia, including percutaneous radiofrequency thermocoagulation, requires cannulation of the foramen ovale. To maximize patient security and cannulation success, a frameless stereotactic system was evaluated in a phantom study, a cadaveric study, and a preliminary clinical trial. Frameless stereotaxy using an optical navigation system, an aiming device, and a noninvasive vacuum mouthpiece-based registration and patient fixation technique was used for the targeting of a test body based on 1-, 3-, and 5-mm axial computed tomographic slices and of the foramen ovale in three cadavers and 15 patients based on 3-mm axial computed tomographic slices. The mean normal (x/y) localization accuracy/standard deviation (n = 360) was 1.31/0.67 mm (1-mm slices), 1.38/0.65 mm (3-mm slices), and 1.84/0.96 mm (5-mm slices). Significantly better results were achieved with 1- and 3-mm slices when compared with 5-mm slices (P < 0.001). The foramen ovale (3 x 6 mm) was successfully cannulated at the first attempt in all cadavers and patients, which indicates clinical localization accuracies better than 1.5 mm in the anteroposterior and 3 mm in the medial-lateral directions. Based on the noninvasive Vogele-Bale-Hohner vacuum mouthpiece, there is no need for invasive head clamp fixation. Imaging, real laboratory simulation, and the actual surgical intervention can be separated in time and location. The presented data suggest that frameless stereotaxy is a predictable and reproducible procedure, which may enhance patient security and cannulation success independent of the surgeon's experience.
    Neurosurgery 11/2006; 59(4 Suppl 2):ONS394-401; discussion ONS402. · 3.03 Impact Factor
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    ABSTRACT: The accuracy of high-resolution ultrasonography (HR-US) in detecting disk displacement and condylar erosion of the temporomandibular joint (TMJ) was evaluated, using corresponding cryosections as a "gold standard". HR-US of the TMJ was performed with a high frequency 12 MHz transducer on 30 preserved autopsy specimens. Succeeding sonography, the autopsy specimens were deep-frozen and cut in paracoronal planes corresponding to the sonographic images. HR-US diagnoses were compared with cryosectional findings in a blinded fashion. HR-US detected 19 (95%) of 20 instances of condylar erosion and 16 (73%) of 22 instances of disk displacement. There were one false-positive finding for condylar erosion and two false-positive findings for disk displacement. The accuracy of HR-US evaluating condylar erosion and disk displacement rated 93% and 73%, respectively. In conclusion, condylar erosion was reliably assessed by HR-US, but the evaluation of disk position was less accurate.
    European Radiology 09/2006; 16(8):1750-6. · 4.34 Impact Factor
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    ABSTRACT: PURPOSE To develop and evaluate a novel technique for frameless stereotactic interventional procedures in various body regions. METHOD AND MATERIALS For the CT scan the patient is immobilized with the BodyFix device (Medical Intelligence, Schwabmünchen, Germany). A helical CT scan is obtained (2,5 mm slice thickness) and sent to the Treon navigation system (Medtronic, USA) via intranet. The target and the pathway are determined on the 3D – CT dataset on the navigation system. The plastic sheath at the skin entrance point is opened and sterile washing and draping is performed. After registration based on the skin markers the Atlas aiming device (Medical Intelligence, Schwabmünchen, Germany) is used for precise alignment of the probe of the navigation system with the preplanned trajectory. The drill is advanced through the targeting device to the preplanned depth as indicated by the navigation system. The novel puncture technique was used in 74 patients for various reasons including bone-tumour biopsies, vertebral-disc biopsy, retrograde drilling of osteochondral lesions, percutaneous fixation of pelvic fractures and radiofrequency ablation of bone tumors. To determine the accuracy the 3D – dataset with the pin in place was superimposed to the 3D – planning CT (with the planned path) and the localization accuracy was evaluated by measuring the distance between the tip of the pin in the intraoperative scan and the desired target in the plan. Results: Depending on the depth of the lesion image-fusion revealed a needle displacement within 1-5,5 mms (mean 3D accuracy: 2,8 mms) in all patients. The mean duration from the CT scan to the control CT with the pin in place was 35 minutes. RESULTS Application of the novel technique allows for precise targeting of different musculoskeletal lesions in the body for various diagnostic and therapeutic procedures. In contrast to conventional CT-guided punctures double-angulated approaches can be easily performed with high precision. CONCLUSION Application of navigation systems in combination with the novel devices allows for precise targeting of different musculoskeletal lesions in the body for various diagnostic and therapeutic procedures. DISCLOSURE R.J.B.: Reto Bale, MD is co-developer of the BodyFix system and the targeting device and will receive financial returns in case the system is sold. PURPOSE To develop and evaluate a novel technique for frameless stereotactic interventional procedures in various body regions. METHOD AND MATERIALS For the CT scan the patient is immobilized with the BodyFix device (Medical Intelligence, Schwabmünchen, Germany). A helical CT scan is obtained (2,5 mm slice thickness) and sent to the Treon navigation system (Medtronic, USA) via intranet. The target and the pathway are determined on the 3D – CT dataset on the navigation system. The plastic sheath at the skin entrance point is opened and sterile washing and draping is performed. After registration based on the skin markers the Atlas aiming device (Medical Intelligence, Schwabmünchen, Germany) is used for precise alignment of the probe of the navigation system with the preplanned trajectory. The drill is advanced through the targeting device to the preplanned depth as indicated by the navigation system. The novel puncture technique was used in 74 patients for various reasons including bone-tumour biopsies, vertebral-disc biopsy, retrograde drilling of osteochondral lesions, percutaneous fixation of pelvic fractures and radiofrequency ablation of bone tumors. To determine the accuracy the 3D – dataset with the pin in place was superimposed to the 3D – planning CT (with the planned path) and the localization accuracy was evaluated by measuring the distance between the tip of the pin in the intraoperative scan and the desired target in the plan. Results: Depending on the depth of the lesion image-fusion revealed a needle displacement within 1-5,5 mms (mean 3D accuracy: 2,8 mms) in all patients. The mean duration from the CT scan to the control CT with the pin in place was 35 minutes. RESULTS Application of the novel technique allows for precise targeting of different musculoskeletal lesions in the body for various diagnostic and therapeutic procedures. In contrast to conventional CT-guided punctures double-angulated approaches can be easily performed with high precision. CONCLUSION Application of navigation systems in combination with the novel devices allows for precise targeting of different musculoskeletal lesions in the body for various diagnostic and therapeutic procedures. DISCLOSURE R.J.B.: Reto Bale, MD is co-developer of the BodyFix system and the targeting device and will receive financial returns in case the system is sold.
    Radiological Society of North America 2005 Scientific Assembly and Annual Meeting; 12/2005
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    ABSTRACT: The aim of this study was to assess the value of multimodality imaging using a novel repositioning device with external markers for fusion of single-photon emission computed tomography (SPECT) and computed tomography (CT) images. The additional benefit derived from this methodological approach was analysed in comparison with SPECT and diagnostic CT alone in terms of detection rate, reliability and anatomical assignment of abnormal findings with SPECT. Fifty-three patients (30 males, 23 females) with known or suspected endocrine tumours were studied. Clinical indications for somatostatin receptor (SSTR) scintigraphy (SPECT/CT image fusion) included staging of newly diagnosed tumours (n=14) and detection of unknown primary tumour in the presence of clinical and/or biochemical suspicion of neuroendocrine malignancy (n=20). Follow-up studies after therapy were performed in 19 patients. A mean activity of 400 MBq of (99m)Tc-EDDA/HYNIC-Tyr(3)-octreotide was given intravenously. SPECT using a dual-detector scintillation camera and diagnostic multi-detector CT were sequentially performed. To ensure reproducible positioning, patients were fixed in an individualised vacuum mattress with modality-specific external markers for co-registration. SPECT and CT data were initially interpreted separately and the fused images were interpreted jointly in consensus by nuclear medicine and diagnostic radiology physicians. SPECT was true-positive (TP) in 18 patients, true-negative (TN) in 16, false-negative (FN) in ten and false-positive (FP) in nine; CT was TP in 18 patients, TN in 21, FP in ten and FN in four. With image fusion (SPECT and CT), the scan result was TP in 27 patients (50.9%), TN in 25 patients (47.2%) and FN in one patient, this FN result being caused by multiple small liver metastases; sensitivity was 95% and specificity, 100%. The difference between SPECT and SPECT/CT was statistically as significant as the difference between CT and SPECT/CT image fusion (P<0.001). Twenty-seven abnormal SPECT findings in 17 patients could not be initially assigned to organs, but were clearly delineated after image fusion. In 21 patients (40%), clinically relevant information was obtained by image fusion as compared with SPECT alone. Co-registration of SPECT and diagnostic CT using a cost-effective immobilisation device provides excellent accuracy for tumour detection of endocrine malignancies and is superior to SPECT and CT alone. Image fusion reduces false positive results and can detect additional lesions. Anatomical information provided by CT enables precise localisation of abnormalities observed in SPECT.
    European journal of nuclear medicine and molecular imaging 12/2005; 32(12):1440-51. · 5.22 Impact Factor
  • RöFo - Fortschritte auf dem Gebiet der R 05/2005; 177. · 1.96 Impact Factor
  • RöFo - Fortschritte auf dem Gebiet der R 05/2005; 177. · 1.96 Impact Factor
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    ABSTRACT: GRUNDLAGEN: Die Lymphknotenmetastasierung zhlt beim kolorektalen Karzinom zu den wichtigsten Prognosefaktoren. Das Konzept des Wchterlymphknotens wird aber durch die Variation aberranter Lymphabflusswege und Skip-Metastasen beim kolorektalen Karzinom gestrt. Fr Patienten mit einem resektablen Kolonkarzinom wrde eine verbesserte Identifikation von Lymphknotenmetastasen einen signifikanten Behandlungsbenefit ermglichen, da die adjuvante Therapie von Vorteil sein wrde. METHODIK: In dieser prospektiven Studie werden Patienten mit histologisch verifiziertem kolorektalem Karzinom properativ mittels CT abdominal vermessen und anatomische Fixpunkte in einem Bildfusionsprogramm markiert. Anschlieend erfolgt kolonoskopisch die peritumorale Radionuklid-Markierung. Eine Stunde danach und properativ am nchsten Tag werden zwei SPECT-Untersuchung in derselben reproduzierbaren Position wie fr das CT durchgefhrt. Durch Bildfusion wird die peritumorale Tracerausbreitung mit Darstellung des Lymphabflussweges und potentieller Skip-Lsionen sichtbar gemacht. Intraoperativ wird mittels einer Gamma-Kamera das Lymphdrainagegebiet identifiziert und damit die Resektionsgrenzen optimiert. Zustzlich werden Wchterlymphknoten ber eine Farbstoffmarkierung dargestellt und im Anschluss an die Resektion gemeinsam mit allen tracermarkierten Lymphknoten immunhistochemisch gezielt auf Mikrometastasen untersucht. ERGEBNISSE: Die Pilotstudie wurde bislang an 11 Patienten durchgefhrt. Vorlufige Ergebnisse zeigen, dass mit Ausnahme eines einzigen Patienten, der wegen einer Nadelstichperforation des Tumors bei der Tracermarkierung vorzeitig operiert wurde, alle Schritte des Konzepts studienkonform durchgefhrt werden konnten. ber die Bildfusion und die genaue pathologische Aufarbeitung liegen bei noch laufender Studie keine Daten vor. Im Mittel wurden pro Patienten 18,5 (95 % CI, 13,2–23,8) Lymphknoten entfernt. SCHLUSSFOLGERUNGEN: Das beschriebene Vorgehen ist prinzipiell machbar und durchfhrbar, obwohl eine schwere Komplikation den Wert dieser aufwendigen Untersuchungskette deutlich schmlert. Eine Aussage bezglich der weiteren Studienziele (Bildfusion, optimiertes Resektionsausma durch Darstellen aberranter Lymphabflusswege, Detektion von Skip-Metastasen und Mikrometastasen) ist bei laufender Studie nicht mglich.BACKGROUND: Lymph node (LN) metastasis is among the most important prognostic factors in colorectal cancer. The concept of sentinel lymph node (SLN) mapping in colorectal cancer is bothered by variations of lymphatic pathways and skip metastases. For patients with resectable colon cancer, improved identification of LN disease would significantly advance patient care by identifying patients likely to benefit from adjuvant therapy. METHODS: Patients with colorectal cancer are enrolled in this prospective study. Anatomical intraabdominal landmarks are assessed using CT-scan and the so-called BodyFix immobilization device. After endoscopic peritumoral tracer injection and prior to the operation procedure, two SPECT scans were performed and images superimposed. Thereby precise localization of tracer activities in LNs and corresponding anatomical sites can be displayed. Intraoperative blue-staining and tracer detection allows accurate resection of the lymph basin. Sentinel nodes are analyzed using immunohistochemistry according to standardized protocols. RESULTS: Eleven patients participated in this pilot study, so far. Preliminary results show that the regimen is feasible although not complication free. In one patient a tumor perforation during endoscopic injection of the tracer led to prematurely operative procedure. A mean of 18.5 LNs (95% CI, 13.2–23.8) per patient were harvested. CONCLUSIONS: The regimen described is feasible, although one major complication occurred, which may diminish the clinical value of this complex multiple step concept. Due to the fact that the study is not closed so far, currently remaining data regarding superimposed imaging, optimized resection margins on the basis of the identification of aberrant lymphatic pathways, detection of skip-metastases and micrometastases are not available.
    European Surgery 01/2005; 37(3):159-163. · 0.26 Impact Factor
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    ABSTRACT: GRUNDLAGEN: Die Lymphknotenmetastasierung zählt beim kolorektalen Karzinom zu den wichtigsten Prognosefaktoren. Das Konzept des Wächterlymphknotens wird aber durch die Variation aberranter Lymphabflusswege und Skip-Metastasen beim kolorektalen Karzinom gestört. Für Patienten mit einem resektablen Kolonkarzinom würde eine verbesserte Identifikation von Lymphknotenmetastasen einen signifikanten Behandlungsbenefit ermöglichen, da die adjuvante Therapie von Vorteil sein würde. METHODIK: In dieser prospektiven Studie werden Patienten mit histologisch verifiziertem kolorektalem Karzinom präoperativ mittels CT abdominal vermessen und anatomische Fixpunkte in einem Bildfusionsprogramm markiert. Anschließend erfolgt kolonoskopisch die peritumorale Radionuklid-Markierung. Eine Stunde danach und präoperativ am nächsten Tag werden zwei SPECT-Untersuchung in derselben reproduzierbaren Position wie für das CT durchgeführt. Durch Bildfusion wird die peritumorale Tracerausbreitung mit Darstellung des Lymphabflussweges und potentieller Skip-Läsionen sichtbar gemacht. Intraoperativ wird mittels einer Gamma-Kamera das Lymphdrainagegebiet identifiziert und damit die Resektionsgrenzen optimiert. Zusätzlich werden Wächterlymphknoten über eine Farbstoffmarkierung dargestellt und im Anschluss an die Resektion gemeinsam mit allen tracermarkierten Lymphknoten immunhistochemisch gezielt auf Mikrometastasen untersucht. ERGEBNISSE: Die Pilotstudie wurde bislang an 11 Patienten durchgeführt. Vorläufige Ergebnisse zeigen, dass mit Ausnahme eines einzigen Patienten, der wegen einer Nadelstichperforation des Tumors bei der Tracermarkierung vorzeitig operiert wurde, alle Schritte des Konzepts studienkonform durchgeführt werden konnten. Über die Bildfusion und die genaue pathologische Aufarbeitung liegen bei noch laufender Studie keine Daten vor. Im Mittel wurden pro Patienten 18,5 (95 % CI, 13,2–23,8) Lymphknoten entfernt. SCHLUSSFOLGERUNGEN: Das beschriebene Vorgehen ist prinzipiell machbar und durchführbar, obwohl eine schwere Komplikation den Wert dieser aufwendigen Untersuchungskette deutlich schmälert. Eine Aussage bezüglich der weiteren Studienziele (Bildfusion, optimiertes Resektionsausmaß durch Darstellen aberranter Lymphabflusswege, Detektion von Skip-Metastasen und Mikrometastasen) ist bei laufender Studie nicht möglich. Schlüsselwörter: Wächterlymphknoten - Kolorektales Karzinom - Bildfusion
    European Surgery 01/2005; 37(3):159-163. · 0.26 Impact Factor
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    ABSTRACT: Lumbar facet nerve (medial branch) blocks are often used to diagnose facet joint-mediated pain. The authors recently described a new ultrasound-guided methodology. The current study determines its accuracy using computed tomography scan controls. Fifty bilateral ultrasound-guided approaches to the lumbar facet nerves were performed in five embalmed cadavers. The target point was the groove at the cephalad margin of the transverse (or costal) process L1-L5 (medial branch T12-L4) adjacent to the superior articular process. Axial transverse computed tomography scans, with and without 1 ml contrast dye, followed to evaluate needle positions and spread of contrast medium. Forty-five of 50 needle tips were located at the exact target point. The remaining 5 were within 5 mm of the target. In 47 of 50 cases, the applied contrast dye reached the groove where the nerve is located, corresponding to a simulated block success rate of 94% (95% confidence interval, 84-98%). Seven of 50 cases showed paraforaminal spread, 5 of 50 showed epidural spread, and 2 of 50 showed intravascular spread. Despite the aberrant distribution, all of these approaches were successful, as indicated by contrast dye at the target point. Abnormal contrast spread was equally distributed among all lumbar levels. Contrast traces along the needle channels were frequently observed. : The computed tomography scans confirm that our ultrasound technique for lumbar facet nerve block is highly accurate for the target at all five lumbar transverse processes (medial branches T12-L4). Aberrant contrast medium spread is comparable to that of the classic fluoroscopy-guided method.
    Anesthesiology 12/2004; 101(5):1195-200. · 6.17 Impact Factor
  • American Journal of Roentgenology 05/2004; 182(4):952-4. · 2.74 Impact Factor
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    ABSTRACT: Successful minimally invasive or imaging-guided operations in patients with primary, recurrent, and persistent hyperparathyroidism are based on the reliability of preoperative parathyroid localization studies. The CT-MIBI image fusion promises a higher diagnostic accuracy than current imaging procedures. The aim of our study was to assess its reliability in correctly detecting enlarged parathyroid glands. In a prospective study 24 consecutive patients underwent CT-MIBI image fusion as preoperative parathyroid localization procedure. The results of technetium 99m sestamibi single photon emission computed tomography (MIBI-SPECT) alone, today the standard method in parathyroid imaging, and CT-MIBI image fusion were analyzed by a blinded reviewer, and the imaging results were compared with the intraoperative findings. For CT-MIBI image fusion a sensitivity of 93% and a specificity of 100% in correctly detecting the position of enlarged parathyroid glands was calculated and compared with a sensitivity of MIBI-SPECT of 31% and a specificity of 87% (P<.001). This new imaging technique enabled us to successfully treat 22 of our patients (92%) with imaging-guided surgery. Twenty (83%) underwent unilateral or minimally invasive operations. CT-MIBI image fusion appears to be superior to MIBI-SPECT in preoperative parathyroid imaging. CT-MIBI image fusion can be performed on existing CT- and MIBI-SPECT units. We recommend this method for preoperative localization in patients with primary, recurrent and persistent hyperparathyroidism.
    Surgery 03/2004; 135(2):157-62. · 3.11 Impact Factor