OBJECTIVE:Thyroid cancer is the most common endocrine cancer. This review evaluates the established use of (18)F-FDG PET/CT in papillary, follicular, Hürthle cell, anaplastic, and medullary thyroid cancers. The significance of incidental diffuse and focal thyroid FDG uptake is discussed. The evolving value of non-FDG radiotracers, including (124)I, (18)F-dihydroxyphenylalanine, and (68)Ga somatostatin analogs, is summarized.CONCLUSION:PET/CT is a valuable imaging test, in the appropriate clinical context, for the management of thyroid cancers.

This chapter discusses FDG normal variant uptake in HIV patients and the role of FDG PET/CT in malignancies in HIV-infected patients, CNS manifestations of HIV, assessing fever of unknown origin in HIV patients, assessing response to highly active antiretroviral therapy, and assessing complications. FDG PET/CT has proven useful in the diagnosis, staging, and detection of metastasis and post treatment monitoring of several malignancies in HIV-infected patients. It also has the ability to make the important distinction between malignancy and infection in the evaluation of CNS lesions, leading to the initiation of the appropriate treatment and precluding the need for invasive biopsy. However, immunosuppression predisposes patients to a number of opportunistic infections, and therefore special care must be taken interpreting FDG PET/CT in HIV patients

OBJECTIVE. Primary hepatobiliary malignancies consist of hepatocellular carcinoma, cholangiocarcinoma, and gallbladder cancer. Benign hepatic lesions include hepatic cysts, hemagiomas, adenomas, and focal nodular hyperplasias. The utility of PET/CT in imaging primary hepatobiliary lesions varies according to the type and location of the lesion.CONCLUSION. There is a consistent benefit to the use of PET/CT for detection and staging, and it ultimately helps to establish the best course of treatment and to determine prognosis. In addition, PET/CT is very useful in local ablative and systemic therapy assessment and surveillance for hepatobiliary malignancies.

OBJECTIVE. This article will discuss the (18)F-FDG normal variant uptake and the role of FDG PET/CT in malignancies in HIV-infected patients, CNS manifestations of HIV, assessing fever of unknown origin in HIV patients, assessing response to highly active antiretroviral therapy and assessing complications.CONCLUSION. FDG PET/CT is a valuable imaging study in the management of HIV-infected patients.

Tumors of cutaneous sweat glands are uncommon and aggressive, with a wide histologic spectrum. Malignant eccrine sweat gland tumors are found in approximately 1 in 13,000 biopsies, with hidradenocarcinomas or malignant hidradenomas accounting for only 6% of these tumors. We present a case report of a 73-year-old man with hidradenocarcinoma of the scalp that was treated with Mohs surgery, but then subsequently recurred and metastasized to a different region of the scalp, the parotids, neck lymph nodes, and lungs. The patient was treated with capecitabine orally for 3 months, and a follow-up PET/CT demonstrated complete metabolic response.

OBJECTIVE:Metastasis is the most common (95%) of liver lesions. Early diagnosis and staging are the keys to treatment planning and prognosis. There is a consistent benefit to the use of PET/CT for detecting hepatic, local, and distant metastases from a variety of primary malignancies, which can contribute to staging and ultimately helps to establish the best course of treatment and to determine prognosis.CONCLUSION:For colorectal cancer, FDG PET and FDG PET/CT are particularly effective for identification of additional hepatic and extrahepatic metastases, frequently upstaging the tumor stage and affecting management. In addition, PET/CT is very useful in local ablative and systemic therapy assessment and surveillance for liver metastases.

1360 Objectives Sustained weight loss after bariatric surgery reflects a complex neurohormonal process that includes hormones that affect gastric emptying. It is postulated that these also affect the emptying of the pouch created by gastric bypass surgery, and are critical to weight loss. We report the kinetics of gastric pouch in a cohort of patients that underwent Rous-en-Y gastric bypass surgery, but failed to sustain weight loss. Methods A review of the institutional database (2008-2009) found 13 cases of gastric pouch emptying scintigraphy. We reviewed the clinical records and imaging findings of these cases and performed detailed kinetic analysis in a cohort of 7 representative cases. Gastric pouch emptying studies were performed with a radiolabeled egg-substitute, and a 2-hour dynamic scan. Results The cohort included women age 27-58 years old that had gastric bypass but unexpectedly failed to sustain weight loss. Except for two cases that were adequately controlled on medication, none were diabetics. None had untreated thyroid disease, or took medications with significant impact on gastric motility. They had no reflux, and endoscopy and UGI exams failed to explain the weight gain. The patterns of pouch emptying in scintigraphy were different from gastric emptying and very variable in our cohort. Some curves followed a linear model, but others were fitted best to complex exponential models that accounted for lags or dumping. In one case oscillations were noted in a background of steady linear emptying that could not be explained by breathing motion or reflux. The half time for pouch emptying ranged from 6 minutes to 625 minutes. Conclusions In our cohort pouch-emptying kinetics was complex and different from gastric emptying. The kinetics varied widely between subjects, although in some instances pouch emptying was so prolonged as to be clearly abnormal. The pouch emptying of a solid test meal is likely nonlinear and different from the linear kinetics of gastric emptying. Research Support Faculty Career Development Award BURA 2008-200

Tumors of the parapharyngeal space (PPS) are uncommon, comprising 0.5% of all head and neck neoplasms. Hemangiomas are responsible for 1% of all such tumors occurring in the PPS. We present the case report of a 55-year-old woman who presented with sensorineural hearing loss. She was evaluated with an magnetic resonance imaging, which showed an incidental finding of a mass in the right PPS. Tagged red blood cell scan showed increased and progressive attenuation in the lesion, which is diagnostic of hemangioma. PET/CT showed minimal background uptake. This added confidence to the diagnosis, and thus avoided an invasive biopsy.