Gallium-68-DOTA-NOC PET/CT appears to be a highly sensitive and specific modality for the detection of gastroenteropancreatic NET. It is better than conventional imaging for the evaluation of gastroenteropancreatic NETs and can have a significant impact on patient management.

In this article, we describe the various causes and patterns of skeletal muscle FDG uptake. Familiarity with these patterns is essential for proper interpretation of clinical FDG PET/CT images.

Ga-DOTA-NOC PET-CT seems to be superior to F-FDG PET-CT for imaging GEP-NETs. However, their role seems to be complementary because combination of Ga-DOTA-NOC PET-CT and F-FDG PET-CT in such patients helps demonstrate the total disease burden and segregate them to proper therapeutic groups.

The purpose of this study was to evaluate the role of 68 Ga-labeled DOTANOC PET/CT for baseline evaluation of patients with head and neck paragangliomas (HNPs). Methods: The data for 26 patients (mean age 6 SD, 34.3 6 10.4 y; 50% men) with known or suspected HNPs who underwent 68 Ga-DOTANOC PET/CT for staging were retrospectively analyzed. PET/CT was performed after intravenous injection of 132-222 MBq of 68 Ga-DOTANOC. The images were evaluated by 2 experienced nuclear medicine physicians in consensus, both qualitatively and quantitatively. The PET/CT findings were grouped as HNPs, paraganglioma at other sites (non-HNPs), and metastatic disease. The size and maximum standardized uptake values (SUVmax) were measured for all lesions. All of the patients also underwent whole-body 131 I-metaiodobenzylgunanidine ( 131 I-MIBG) scintigraphy and conventional imaging (CT/MR imaging) of the head and neck region. Their results were compared with those of 68 Ga-DOTANOC PET/CT. Results: 68 Ga-DOTANOC PET/CT findings were positive in all 26 patients, and 78 lesions were detected. PET/CT imaging demonstrated 45 HNPS, 10 non-HNPs, and 23 metastatic sites. Fifteen patients (57.6%) had more than one site of disease on PET/ CT. Among 45 HNPs, 26 were carotid body tumors (CBTs), 15 glomus jugulare, 3 glomus tympanicum, and 1 laryngeal paraganglioma. A positive correlation was seen between size and SUVmax of HNPs (r 5 0.323; P 5 0.030). The SUVmax of the CBTs was higher than that of jugulotympanic paragangliomas (P 5 0.026). No correlation was seen between size and SUVmax (r 5 0.069; P 5 0.854) of non-HNPs. The size and SUVmax of non-HNPs were significantly less than those of HNPs (P 5 0.029 and 0.047, respectively). 131 I-MIBG scintigraphy showed only 30 of the 78 lesions and was inferior to PET/CT (P , 0.0001). Conventional imaging (CT/MR imaging) was positive for 42 of 49 head and neck lesions and was inferior to PET/CT on direct comparison (P 5 0.015). A combination of CT/MR imaging and 131 I-MIBG scintigraphy detected only 53 of 78 (67.9%) lesions and was also inferior to PET/CT (P , 0.0001). Conclusion: 68 Ga-DOTANOC PET/CT is useful for the baseline evaluation of patients with HNPs and can demonstrate synchronous paragangliomas at other sites and distant metastases. It is superior to 131 I-MIBG scintigraphy and conventional imaging (CT/MR imaging) for this purpose.

Diuretic (18)F-FDG PET/CT is highly sensitive and specific and plays an important role in improving detection of the primary tumour and locoregional staging of urinary bladder tumours. Diuretic (18)F-FDG PET/CT demonstrated a higher diagnostic value when compared with CECT in these patients.

SUVmax measured on (68)Ga-DOTANOC PET/CT is an independent, positive prognostic factor in patients with well-differentiated NET and is superior to SUVmax on (18)F-FDG PET/CT and conventional clinicopathological factors for predicting PFS.

Bone scintigraphy is a sensitive and popular method for imaging a wide array of benign or malignant skeletal abnormalities. However, the uptake of tracers used for bone scintigraphy may be observed in various extraosseous sites, thereby limiting its specificity. It is difficult to correctly localize such sites of uptake on planar bone scintigraphy alone. The addition of hybrid single-photon emission computed tomography-computed tomography (SPECT-CT) under such circumstances is very useful. The present essay illustrates the commonly encountered extraosseous uptake of 99m Tc-meth-ylene diphosphonate (MDP) and the usefulness of hybrid SPECT-CT in clarifying 99m Tc-MDP uptake. T he ability to assess new bone formation makes bone scintigraphy a popular noninvasive diagnostic technique for imaging the skeletal system. Pathologic entities that commonly demonstrate increased uptake on bone scintigraphy are primary bone tumors, skeletal metasta-ses, infections, and sites of skeletal trauma. Bone-seeking tracers such as 99m Tc-methylene diphosphonate (MDP) and its analogs localize to bone by chemisorption to the surface of hydroxyapatite crystals (1). Sites of new bone formation show increased uptake because of high regional perfusion and increased areas of proliferation. On occasion, certain abnormal processes involving soft tissues can also cause skeletal accumulation of radiotracer (extraosseous uptake) on bone scintigraphy apart from the physiologic excretion of tracer through the urinary tract (2). Probable mechanisms that have been proposed to explain extraosseous uptake of 99m Tc-MDP include a) increased regional vascularity and per-meability; b) tumor necrosis with or without calcification; c) metastatic calcification in renal failure; d) increased tissue calcium concentration; e) serum hypocalcemia of any etiology; f) presence of collagen; and g) improper labeling of the radionuclide (3, 4). Knowledge regarding these potentially confusing entities is important because they may hinder correct interpretation of the disease in question. Identification of such nonosseous uptake becomes particularly difficult if planar scintigraphy is used alone. Additional use of hybrid single-photon emission computed tomography (SPECT)-computed tomography (CT) helps in proper anatomical localization of abnormal uptake noted on bone scintigraphy and improves the quality of interpretation. SPECT-CT increases the sensitivity of bone scintigraphy by detecting additional lesions, and the exclusion of sites of physiological tracer uptake also increases specificity. Attenuation and photon scatter correction of nuclear medicine images by hybrid imaging helps us to obtain more accurate image data. The functional significance of indeterminate bone lesions detected on anatomical imaging studies can also be characterized by SPECT-CT. This pictorial essay reviews a few examples of abnormal processes that may cause extraosseous uptake on bone scintigraphy encountered at our institute and highlights the significance of proper anatomical localizati...

(68)Ga-DOTANOC PET/CT is useful for diagnosis/staging and restaging of patients with pancreatic NET. It demonstrates more lesions compared to CIM and is more specific.