68Ga-DOTATOC PET/CT in the localization of head and neck paraganglioma compared with 18F-DOPA PET/CT and 123I-MIBG SPECT/CT.

PURPOSE: 18F-Fluoro-L-dihydroxyphenylalanine (18F-DOPA) PET offers high sensitivity and specificity in the imaging of non-malignant head and neck paraganglioma (HNPGL) but lower sensitivity in metastatic disease of these neuroendocrine tumours (NET). In contrast to the radiotracer 18F-DOPA, both 123I-meta-iodo-benzylguanidine (123I-MIBG) and 68Ga-DOTA-Tyr3-octreotide (68Ga-DOTA-TOC) offer valuable clinical information on norepinephrine and somatostatin (SST) receptor status for planning 131I-MIBG and radionuclide peptide therapy (PRRT), respectively. Therefore, we compared 68Ga-DOTA-TOC and 18F-DOPA PET/CT with 123I-MIBG planar and SPECT/CT imaging, for the detection of HNPGL. Combined cross-sectional imaging was the reference standard. METHODS: A total of 3 men and 7 women (age range 22 to 73 years) with anatomical and/or histologically proven HNPGL were included in this study. Of these patients, 3 patients had metastatic HNPGL. Comparative evaluation included morphological imaging with CT and functional imaging with 68Ga-DOTA-TOC and 18F-DOPA PET, including 123I-MIBG imaging. The imaging results were analysed on a per-patient and per-lesion basis. RESULTS: On a per-patient analysis, the detection rate of both 68Ga-DOTA-TOC PET/CT and 18F-DOPA PET/CT was 100%, that of planar 123I-MIBG imaging 10.0% and that of SPECT/CT 20.0%. On a per-lesion basis and in reference to diagnostic CT, the sensitivity of 68Ga-DOTA-TOC PET/CT was 100% (McNemar, P < 0.5), that of 18F-DOPA PET/CT was 66.7% (McNemar, P < 0.01), that of planar 123I-MIBG imaging was 3.7% (McNemar, P < 0.0001), and that of SPECT/CT was 7.4% (McNemar, P < 0.0001) in HNPGL. Overall, 68Ga-DOTA-TOC PET identified 29 lesions and anatomical imaging identified 27 lesions. 18F-DOPA PET identified 18 lesions, whereas planar 123I-MIBG imaging identified 1 lesion and SPECT/CT 2 lesions. CONCLUSION: 68Ga-DOTA-TOC PET/CT is superior for imaging, non-malignant and metastatic HNPGL compared to 18F-DOPA PET/CT and planar 123I-MIBG imaging, including SPECT/CT, particularly in bone lesions. Combined functional/anatomical imaging (68Ga-DOTA-TOC PET/CT) enables excellent delineation of tumour extent in these rare tumour entities. Compared to 123I-MIBG scintigraphy, 68Ga-DOTA-TOC PET appears far more useful for planning radionuclide therapy in patients with surgically inoperable tumours or metastatic disease.

CT-based SPECT attenuation correction and assessment of infarct size: results from a cardiac phantom study.

RATIONALE: Myocardial perfusion SPECT is a commonly performed, well established, clinically useful procedure for the management of patients with coronary artery disease. However, the attenuation of photons from myocardium impacts the quantification of infarct sizes. CT-Attenuation Correction (AC) potentially resolves this problem. This contention was investigated by analyzing various parameters for infarct size delineation in a cardiac phantom model. METHODS: A thorax phantom with a left ventricle (LV), fillable defects, lungs, spine and liver was used. The defects were combined to simulate 6 infarct sizes (5-20% LV). The LV walls were filled with 100120 kBq/ml 99mTc and the liver with 10-12 kBq/ml 99mTc. The defects were filled with water of 50% LV activity to simulate transmural and non-transmural infarction, respectively. Imaging of the phantom was repeated for each configuration in a SPECT/CT system. The defects were positioned in the anterior as well as in the inferior wall. Data were acquired in two modes: 32 views, 30 s/view, 180° and 64 views, 15 s/view, 360° orbit. Images were reconstructed iteratively with scatter correction and resolution recovery. Polar maps were generated and defect sizes were calculated with variable thresholds (40-60%, in 5% steps). The threshold yielding the best correlation and the lowest mean deviation from the true extents was considered optimal. RESULTS: AC data showed accurate estimation of transmural defect extents with an optimal threshold of 50% [non attenuation correction (NAC): 40%]. For the simulation of non-transmural defects, a threshold of 55% for AC was found to yield the best results (NAC: 45%). The variability in defect size due to the location (anterior versus inferior) of the defect was reduced by 50% when using AC data indicating the benefit from using AC. No difference in the optimal threshold was observed between the different orbits. CONCLUSION: Cardiac SPECT/CT shows an improved capability for quantitative defect size assessment in phantom studies due to the positive effects of attenuation correction.

Compared to 123I-MIBG SPECT/CT, 18F-DOPA PET/CT provides accurate tumor extent in patients with extra-adrenal paraganglioma.

AIM: The aim of this study was to compare the accuracy of 123I-MIBG SPECT/CT with that of 18F-DOPA PET/CT for staging extra-adrenal paragangliomas (PGLs) using both functional and anatomical images (i.e., combined cross-sectional imaging) as the reference standards. METHODS: Three men and seven women (age range 26-73 years) with anatomical and/or histologically proven disease were included in this study. Three patients had either metastatic head-and-neck paragangliomas (HNPGLs) or multifocal PGL, and seven patients had nonmetastatic disease. Comparative evaluation included morphological imaging with CT, functional imaging with 18F-DOPA PET, and 123I-MIBG imaging including SPECT/CT. Imaging results were analyzed on a per-patient and per-lesion basis. RESULTS: On a per-patient basis, 18F-DOPA PET's detection rate for both nonmetastatic and metastatic/multifocal disease was 100%, whereas that of planar 123I-MIBG imaging alone was 10.0% and that of 123I-MIBG SPECT/CT was 20.0%. Overall, on a per-lesion basis, 18F-DOPA PET showed a sensitivity of 69.2% (McNemar p < 0.001) compared with anatomical imaging. Sensitivity of planar 123I-MIBG scintigraphy was 5.6%, and that of SPECT/CT was 11.1% (McNemar p < 0.0001). Overall, 18F-DOPA PET identified 18 lesions, and anatomical imaging identified 26 lesions; planar 123IMIBG imaging identified only 1 lesion, and SPECT/CT, 2 lesions. CONCLUSION: 18F-DOPA PET is more sensitive than is 123I-MIBG imaging, including SPECT/CT, for staging HNPGL. Combined functional and anatomical imaging (PET/CT) is indicated to exclude metastatic disease in extra-adrenal PGL.

(68)Ga-DOTATOC PET/CT provides accurate tumour extent in patients with extraadrenal paraganglioma compared to (123)I-MIBG SPECT/CT.

PURPOSE: The aim of this study was to compare the accuracy of (123)I-MIBG SPECT/CT with that of (68)Ga-DOTATOC PET/CT for staging extraadrenal paragangliomas (PGL) using both functional and anatomical images (i.e. combined cross-sectional imaging) as the reference standards. METHODS: The study included three men and seven women (age range 26 to 73 years) with anatomical and/or histologically proven disease. Three patients had either metastatic head and neck PGL (HNPGL) or multifocal extraadrenal PGL, and seven patients had nonmetastatic extraadrenal disease. Comparative evaluation included morphological imaging with CT, functional imaging with (68)Ga-DOTATOC PET, and (123)I-MIBG imaging. The imaging results were analysed on a per-patient and on a per-lesion basis. RESULTS: On a per-patient basis, the detection rate of (68)Ga-DOTATOC PET was 100 %, whereas that of planar (123)I-MIBG imaging was 10.0 % and with SPECT/CT 20.0 % for both nonmetastatic and metastatic/multifocal extraadrenal PGL. On a per-lesion basis, the overall sensitivity of (68)Ga-DOTATOC PET was 100 % (McNemar p < 0.5), that of planar (123)I-MIBG imaging was 3.4 % (McNemar p < 0.001) and that of SPECT/CT was 6.9 % (McNemar p < 0.001). Both (68)Ga-DOTATOC PET and anatomical imaging identified 27 lesions. Planar (123)I-MIBG imaging identified only one lesion, and SPECT/CT two lesions. Two additional lesions were detected by (68)Ga-DOTATOC PET but not by either (123)I-MIBG or CT imaging. CONCLUSION: Our analysis in this patient cohort indicated that (68)Ga-DOTATOC PET/CT is superior to (123)I-MIBG SPECT/CT, particularly in head and neck and bone lesions, and provides valuable information for staging extraadrenal PGL, particularly in patients with surgically inoperable tumours or multifocal/malignant disease.

A retrospective comparison between 68Ga-DOTA-TOC PET/CT and 18F-DOPA PET/CT in patients with extra-adrenal paraganglioma.

PURPOSE: (18)F-Fluoro-L-dihydroxyphenylalanine ((18)F-DOPA) PET offers high sensitivity and specificity in the imaging of nonmetastatic extra-adrenal paragangliomas (PGL) but lower sensitivity in metastatic or multifocal disease. These tumours are of neuroendocrine origin and can be detected by (68)Ga-DOTA-Tyr(3)-octreotide ((68)Ga-DOTA-TOC) PET. Therefore, we compared (68)Ga-DOTA-TOC and (18)F-DOPA as radiolabels for PET/CT imaging for the diagnosis and staging of extra-adrenal PGL. Combined cross-sectional imaging was the reference standard. METHODS: A total of 5 men and 15 women (age range 22 to 73 years) with anatomical and/or histologically proven extra-adrenal PGL were included in this study. Of these patients, 5 had metastatic or multifocal lesions and 15 had single sites of disease. Comparative evaluation included morphological imaging with CT and functional imaging with (68)Ga-DOTA-TOC PET and (18)F-DOPA PET. The imaging results were analysed on a per-patient and a per-lesion basis. The maximum standardized uptake value (SUVmax) of each functional imaging modality in concordant tumour lesions was measured. RESULTS: Compared with anatomical imaging, (68)Ga-DOTA-TOC PET and (18)F-DOPA PET each had a per-patient and per-lesion detection rate of 100% in nonmetastatic extra-adrenal PGL. However, in metastatic or multifocal disease, the per-lesion detection rate of (68)Ga-DOTA-TOC was 100% and that of (18)F-DOPA PET was 56.0%. Overall, (68)Ga-DOTA-TOC PET identified 45 lesions; anatomical imaging identified 43 lesions, and (18)F-DOPA PET identified 32 lesions. The overall per-lesion detection rate of (68)Ga-DOTA-TOC PET was 100% (McNemar, P < 0.5), and that of (18)F-DOPA PET was 71.1% (McNemar, P < 0.001). The SUVmax (mean ± SD) of all 32 concordant lesions was 67.9 ± 61.5 for (68)Ga-DOTA-TOC PET and 11.8 ± 7.9 for (18)F-DOPA PET (Mann-Whitney U test, P < 0.0001). CONCLUSION: (68)Ga-DOTA-TOC PET may be superior to (18)F-DOPA PET and diagnostic CT in providing valuable information for pretherapeutic staging of extra-adrenal PGL, particularly in surgically inoperable tumours and metastatic or multifocal disease.