Ramya Soundararajan

⁶⁸Ga-DOTANOC PET/CT in patients with carcinoma of unknown primary of neuroendocrine origin.

Objective: To evaluate the role of 68Ga-DOTANOC (68Gallium-labeled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI3-octreotide) PET/CT for localization of the primary tumor in patients with carcinoma of unknown primary of neuroendocrine origin. Material and Methods: Twenty patients (median age, 55 years; male 10) with histopathologically proven metastatic neuroendocrine tumor and no localization of primary tumor on conventional imaging were included in the study. PET/CT was done after injection of 132–222 MBq (4–6 mCi) of 68Ga-DOTANOC. Images were evaluated by 2 experienced nuclear medicine physicians both qualitatively as well as quantitatively (maximum standardized uptake value). Histopathology (when available) and/or follow-up imaging with biochemical markers were taken as reference standard. Results: 68Ga-DOTANOC PET/CT localized the primary tumor in 12/20 (60%) patients. Midgut was the most common site of primary tumor (n = 9); duodenum (4), ileum (4), and colon (1). In 1 patient each the primary was localized to the pancreas, stomach, and lung. In these 12 patients, significant correlation was found between maximum standardized uptake value of primary tumor and metastasis (&rgr; = 0.615; P = 0.041). Even in patients in whom no primary tumor was localized, additional sites of metastatic disease were observed when compared with conventional imaging, mostly in lymph nodes and bones. There was a change in management in 3/20 patients (15%), who underwent surgery. In the remaining 17 patients, demonstration of somatostatin receptor expression by PET/CT made them suitable candidate for peptide receptor radionuclide therapy. Conclusion: 68Ga-DOTANOC PET/CT seems to be a promising modality for detecting primary tumor in patients with carcinoma of unknown primary of neuroendocrine origin.

Spectrum of 18F-FDG PET/CT Findings in Patients Presenting With Fever of Unknown Origin

OBJECTIVE The objective of this article is to provide an illustrative tutorial highlighting the clinical utility of (18)F-FDG PET/CT for imaging patients presenting with fever of unknown origin (FUO). CONCLUSION 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.

SPECT-CT for characterization of extraosseous uptake of 99mTc-methylene diphosphonate on bone scintigraphy.

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 99mTc-methylene diphosphonate (MDP) and the usefulness of hybrid SPECT-CT in clarifying 99mTc-MDP uptake.

Prognostic factors in pediatric differentiated thyroid cancer patients with pulmonary metastases.

Abstract Aim: This study was aimed at identifying the prognostic factors predicting remission in pediatric differentiated thyroid cancer (DTC) patients presenting with pulmonary metastases. Little is known about the prognostic factors in reference to pediatric DTC patients presenting with pulmonary metastases. Methods: Fifty-three DTC patients aged ≤21 years were diagnosed with pulmonary metastases at initial presentation. The demographic and disease characteristics were compared between the patients who achieved remission and those who did not. Results: During the median follow-up of 72 months, 38 patients became disease free, 14 patients had biochemically and/or structurally persistent disease, and one patient died due to disease progression. Patient age >15 years, presence of macronodular pulmonary metastases, and surgical methods lesser than total/near-total thyroidectomy were identified as factors associated with reduced odds of remission. Conclusion: This study describes the disease course and depicts the disease related prognostic factors in pediatric DTC patients with pulmonary metastases.

Metabolic Skeletal Superscan on 18F-FDG PET/CT in a Case of Acute Lymphoblastic Leukemia.

Superscan is a well-known finding described in skeletal scintigraphy characterized by intense radiotracer uptake in axial skeleton and decreased uptake in soft tissues and kidneys. Metabolic skeletal superscan has also been described in ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in various conditions. We describe here a case of 12-year-old boy who presented with a scalp swelling, progressive pallor, easy fatigability, poor appetite, and fever for 6 months. The initial diagnosis was inconclusive. ¹⁸F-FDG PET/CT revealed metabolic skeletal superscan and the final histopathological diagnosis was acute lymphoblastic leukemia.

A curious case of refractory hypothyroidism due to selective malabsorption of oral thyroxine.

There are very few cases in the literature in which refractory persistent hypothyroidism responded only to parenteral doses of levothyroxine and no evidence of any malabsorptive disorder could be identified. Here, we present a rare case of a 35-year-old woman with refractory hypothyroidism who responded only to intravenous doses of levothyroxine. We also discuss possible causes for the same.

Intermediate-risk differentiated thyroid carcinoma patients who were surgically ablated do not need adjuvant radioiodine therapy: long-term outcome study

The mute question is whether patients with DTC of intermediate risk of recurrence, second most common presentation, who were surgically ablated in the first place, ever needed adjuvant RAI therapy? This study exclusively evaluated the long‐term outcome in intermediate‐risk patients with DTC.

Differentiated thyroid cancer in patients over 60 years of age at presentation: A retrospective study of 438 patients

OBJECTIVES The aim of this study is to identify the prognostic factors predicting remission and subsequent disease relapse in patients with differentiated thyroid cancer (DTC) greater than 60years of age. MATERIALS AND METHODS The institute thyroid cancer database had 4370 patients with DTC, of which 447 (10%) were aged>60. However, 9 patients were excluded due to follow-up less than 1year. The prognostic factors in the remaining 438 patients were studied. RESULTS Among the 438 patients, 311 (71%) had only loco-regional disease (M0) and 127 (29%) had distant metastases (M1) at the time of initial presentation. The host factors predictive of distant metastases at presentation were female gender, primary tumor size (>4cm), follicular histology, and extra-thyroidal extension. Among Mo patients, 195 (63%) achieved complete remission while only 12 (9%) M1 patients did so. Average number of radioactive iodine ((131)I) doses administered to achieve complete remission was 2.3 (range, 1-6) and the mean cumulative dose was 3404MBq (range, 925-46,250MBq). In multivariate logistic regression among M0 patients, follicular histology, nodal metastases, and surgical treatment lesser than total/near-total thyroidectomy and among M1 patients, site of distant metastases (skeletal and multiple sites) were independent factors predicting non-remission. Among the patients (both M0 and M1) who achieved remission, factors associated with disease recurrence were primary tumor size (>4cm), nodal metastases, pulmonary metastases, and non-remission after first dose of radioactive iodine and were associated with greater chances of disease relapse. CONCLUSION This study highlights that DTC in older patients behaves more aggressively than in adults age<60years, and identifies several prognostic factors for remission and subsequent relapse.

Metastatic neuroendocrine carcinoma presenting as a "Superscan" on 68Ga-DOTANOC somatostatin receptor PET/CT.

PET/CT imaging using Ga-labeled somatostatin analogs has become a popular noninvasive diagnostic modality in the workup of patients with neuroendocrine tumors. A 65-year-old man with pancreatic neuroendocrine tumor with confirmed liver metastases on conventional imaging underwent restaging Ga-DOTANOC PET/CT to monitor response to cold octreotide therapy. Previous PET/CT had shown presence of multiple liver and skeletal metastases along with a primary pancreatic tumor showing intense tracer uptake. The present PET/CT study showed an increase in number and uptake of the metastatic lesions suggestive of progressive disease resulting in the appearance of a superscan.

Spectrum of Physiologic and Pathologic Skeletal Muscle 18 F-FDG Uptake on PET/CT

OBJECTIVE Skeletal muscle (18)F-FDG uptake on PET/CT can be either physiologic or related to a variety of different pathologic conditions. FDG PET/CT can be used for assessment of primary and metastatic tumors and infective or inflammatory conditions affecting the musculature. CONCLUSION 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.