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.

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 appears to be useful in patients with gastrinoma with negative or equivocal results on CECT, especially the latter group.

• ( 68 ) Ga-DOTA-NOC PET-CT seems useful in patients with phaeochromocytoma and paraganglioma. • This prospective single centre study showed that it has high diagnostic accuracy. • (68) Ga-DOTA-NOC PET-CT seems superior to (131) I-MIBG in these patients.

Background Thyroglobulin (Tg) is a specific tumor marker for differentiated thyroid cancer (DTC). However, in the presence of an antithyroglobulin antibody (TgAb), it becomes unreliable. The purpose of the study was to assess the long-term outcome of DTC patients with raised TgAb. Method In a retrospective study, we included patients with DTC who had raised TgAb following total thyroidectomy. We excluded patients with persistently raised Tg (≥ 1 ng/ml) or radioiodine avid disease. Serial TgAb levels, excellent response (ER), incomplete response (IR), and anatomical recurrence were evaluated. Results A total of seventy-six patients were included in the study. Patients with IR had higher baseline TgAb (1071.27 ± 1216.17 vs. 99.61 ± 91.29 IU/ml, p < 0.001) and central compartment lymph node metastases (70.8% vs. 46.4%, p = 0.035) in comparison to those in the ER group. In the first follow-up, 64 (84.2%) patients had a stable or fall in the TgAb (0 to − 98.3%). Sixty-eight patients received high-dose radioiodine therapy (RIT). Out of these, 59 (86.5%) had transient, and 51 (75%) had a long-term fall in TgAb. After a follow-up period of 58.74 ± 26.26 months, 63.2% (48 out of 76) patients had IR. Nine (11.8%) patients had a rising TgAb level (3.7–170.9%) from baseline. Eleven patients underwent 18F-FDG PET/CT, and five of them demonstrated metabolically active recurrent disease. Three patients underwent cervical lymph nodes dissection. None of the patients died during the follow-up period. Conclusion High post-operative TgAb levels and central compartment lymph nodal metastases are risk factors for IR. RIT leads to a significant fall in the TgAb in these patients. The low level of raised TgAb is associated with an excellent outcome. Patients with recurrences had very high baseline TgAb > 1000 IU/ml. Raised TgAb was associated with good clinical outcomes and not associated with increased mortality.

Primary pulmonary lymphoma (PPL) is an uncommon entity of non-Hodgkin lymphoma, which accounts for <1% of all cases of lymphoma. We present two rare cases of PPL of diffuse large B-cell lymphoma, which underwent 18fluorine fluoro-deoxy-glucose positron emission tomography-computed tomography for initial staging and response evaluation after chemotherapy.

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FDG PET/CT is a powerful tool in localizing an inciting source in patients with FUO. The high sensitivity of FDG PET/CT for diagnosing infective, inflammatory, and neoplastic processes can be exploited in this setting because these processes are often the common causes of FUO.