The aim of this study was to evaluate the diagnostic value of a new somatostatin analog, Ga-68-labeled 1,4,7,10-tetraazacyclo-dodecane-N,N',N '',N '''-tetraacetic acid-D-Phe(1)-Tyr(3)-octreotide (Ga-68-DOTA-TOC), for PET in patients with known or suspected neuroendocrine tumors. PET was compared with conventional scintigraphy and dedicated CT. Methods: 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 Ga-68-DOTA-TOC. Imaging results of PET were compared with Tc-99m-labeled hydrazinonicotinyl-Tyr(3)-octreotide (Tc-99m-HYNIC-TOC) and In-111-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. Results: 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. Ga-68-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. Conclusion: Ga-68-DOTA-TOC PET shows a significantly higher detection rate compared with conventional so-matostatin receptor scintigraphy and diagnostic CT with clinical impact in a considerable number of patients.

BACKGROUND Even as PET/CT provides valuable diagnostic information in a great number of clinical indications, availability of hybrid PET/CT scanners is mainly limited to clinical centers. A software-based image fusion would facilitate combined image reading of CT and PET data sets if hardware image fusion is not available. To analyze the relevance of retrospective image fusion of separately acquired PET and CT data sets, we studied the accuracy, practicability and reproducibility of three different image registration techniques. METHODS We evaluated whole-body 18F-FDG-PET and CT data sets of 71 oncologic patients. Images were fused retrospectively using Stealth Station System, Treon (Medtronic Inc., Louisville, CO, USA) equipped with Cranial4 Software. External markers fixed to a vacuum mattress were used as reference for exact repositioning. Registration was repeated using internal anatomic landmarks and Automerge software, assessing accuracy for all three methods, measuring distances of liver representation in CT and PET with reference to a common coordinate system. RESULTS On first measurement of image fusions with external markers, 53 were successful, 16 feasible and 2 not successful. Using anatomic landmarks, 42 were successful, 26 feasible and 3 not successful. Using Automerge Software only 13 were successful. The mean distance between center points in PET and CT was 7.69±4.96 mm on first, and 7.65±4.2 mm on second measurement. Results with external markers correlate very well and inaccuracies are significantly lower (P<0.001) than results using anatomical landmarks (10.38±6.13 mm and 10.83±6.23 mm). Analysis revealed a significantly faster alignment using external markers (P<0.001). CONCLUSIONS External fiducials in combination with immobilization devices and breathing protocols allow for highly accurate image fusion cost-effectively and significantly less time, posing an attractive alternative for PET/CT interpretation when a hybrid scanner is not available.

To perform focused or minimally invasive surgery for hyperparathyroidism (HPT) exact preoperative localization is mandatory. Computed tomography–99mTc-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.

Ga-68-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 (Y-90-DOTA-TOC or Lu-177-DOTA-octreotate) is a choice of treatment that also requires an accurate diagnostic modality for early evaluation of treatment response. Our study compared Ga-68-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. Methods: 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. Ga-68-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, F-18-FDG, were used as the reference standard. Results: According to the reference standard, Ga-68-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. Ga-68-DOTATOC 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 Ga-68-DOTA-TOC in 1 patient and progressive liver disease not detected on Ga-68-DOTA-TOC in 3 patients. Quantitative SUV analysis of individual tumor lesions showed a large range of variability. Conclusion: Ga-68-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.

BACKGROUND DATA: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.METHODS: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.RESULTS: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%.CONCLUSIONS: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.

One of the major advantages of sonography compared to other modalities for imaging of the soft tissues, such as MRI and CT, is its ability to acquire images in virtually every orientation along the course of a peripheral nerve. This however results in a very complex regional topographic anatomy. Therefore a well-founded knowledge of regional anatomy and topography is an indispensable prerequisite for the sonographic assessment of peripheral nerves. The typical sonographic appearance of nerves must be distinguished from other soft tissue structures and may change substantially depending on the type of surrounding tissue elements. Usually nerves present as longitudinal bands with a mixture of hyperechoic (peri- and epineurium) and hypoechoic elements (fascicle groups) in longitudinal sonograms. In the transverse plane a variable number of hypoechoic dots (fascicle groups) is surrounded by hyperechoic epineurium with hyperechoic septa between the fascicles ().

PURPOSE: To determine the accuracy of frameless stereotactic computed tomographic (CT)-guided wire placement for percutaneous fixation of posterior pelvic ring fractures in human cadavers.MATERIALS AND METHODS: 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.RESULTS: 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.CONCLUSIONS: The described technique enables accurate placement of pins in the pelvis and may be useful for percutaneous orthopedic procedures.

PURPOSE: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.METHODS: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.RESULTS: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.CONCLUSION: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.

This study describes a new method for the treatment of osteochondritis dissecans (OCD) in the medial talar dome. Ten cadaveric lower extremities were used to develop and evaluate a retrograde osteochondral grafting technique applying computer-assisted surgery. With the help of a computed tomography (CT)-based navigation system, a guide wire was placed from the lateral talar process into the posteromedial talar trochlea where OCD lesions are predominantly located. Cannulated reamers and arthroscopic shavers were used for the preparation of the recipient hole. The grafts, with diameters of 4.5 mm, 6.5 mm or 8.5 mm were harvested from the lateral femoral trochlea and inserted in a retrograde fashion. The last five cadavers were analyzed for accuracy of surface reconstruction and graft stability. For this purpose a medial malleolar osteotomy and a CT scan was performed. We found steps in the joint surface to range from 0.5 mm to 1.5 mm (mean 0.9 mm, SD 0.4) with the graft always below the surrounding cartilage. Graft subsidence occurred at an applied force of 26.4 +/- 4.6 N. This study indicates that osteochondral cylinders can be inserted in a retrograde fashion to reconstruct the posteromedial talus. Good surface congruency and sufficient graft stability can be achieved.

The aim of this study was to describe the anatomical structures that show uptake of the somatostatin analogue octreotide in patients with thyroid-associated orbitopathy (TAO). The study population comprised a series of 20 TAO patients attending the out-patient thyroid clinic and 12 patients presenting head or neck tumours. Scintigraphy was carried out with our newly developed tracer, technetium-99m labelled EDDA-HYNIC-TOC (99mTc-TOC). Morphological imaging was done with either magnetic resonance imaging or X-ray computed tomography without contrast medium. Both imaging procedures were done within an interval of 3–4 weeks. For the image fusion procedure, specific external reference markers were used for each imaging modality. The markers were screwed onto a reference frame, which was held in place via a vacuum-fixed mouthpiece. The anatomical structure showing tracer uptake that was most frequently recognised was the lacrimal gland, followed by the retronasal area, cervical lymph structures, salivary glands, the anterior insertion points of the extra-ocular muscles and discrete areas of the neck extensor muscles. The lacrimal gland and the retronasal area showed the highest and most frequent uptake of 99mTc-TOC in TAO patients, whereas such uptake did not occur in the retrobulbar space. In spite of knowledge of these results of image fusion, no changes in the involved structures could be detected on morphological imaging. It is concluded that binding of 99mTc-TOC is more frequently localised to the anterior compartment of the eye and to the neck. The previously used term "orbital" uptake should be abandoned and replaced by a descriptive term relating to the anatomically recognised structure showing tracer accumulation, i.e. the lacrimal gland. The uptake of octreotide by lymphoid and salivary glands opens a new field of investigation related to the physiology of somatostatin.

Background. In the surgical repair of facial nerve paralysis, a tension-free end-to-end coaptation of the trunk or its branches with or without rerouting isfunctionally superior to grafting. Assuming that a lengthening of all branches of the parotid plexus can be attained by removal of the superficial part of the parotid gland and mobilization of the branches, we performed an anatomic study.Methods. The parotid regions of 10 cadavers were dissected to investigate the length gained for the branches of the parotid plexus by this technique. Every branch at the upper and ventral border of the gland was marked by a surgical suture. After removing the superficial part of the parotid gland, the branches were cut at the suture, and the proximal stump was drawn toward the distal stump. The distance of the overlapping stumps was measured by means of an electronic gliding caliper. In addition, in five specimens only the trunk of the facial nerve was dissected by the same method, and the distance of the overlapping stumps was measured.Results and Conclusions. The results demonstrate that removing the superficial part of the parotid gland may be sufficient to enable direct coaptation without nerve grafting. Cut temporal or zygomatic branches with a gap of up to 15 mm and cut buccal or marginal mandibular branches with a gap of up to 23 mm can be bridged by mobilization of just the proximal stumps. This technique may also be used to bridge a 17-mm gap of the trunk of the facial nerve. (C) 2002 Wiley Periodicals, Inc. Head Neck 24: 10471053,2002