Rathan M. Subramaniam

This American College of Radiology and American College of Nuclear Medicine joint clinical practice parameter is for performance of dopamine transporter single photon emission computed tomography (SPECT) imaging, for patients with movement disorders. Parkinsonian syndrome (PS) consists of a group of neurodegenerative diseases including Parkinson disease (PD), progressive supranuclear palsy (PSP), multiple system atrophy (MSA), corticobasal degeneration (CBD), and dementia with Lewy bodies (DLB). Accurate diagnosis of PS is critical for clinical management. An important diagnostic dilemma is the differentiation of PS and non-neurodegenerative disorders, such as essential tremor (ET) or drug-induced tremor, due to the overlap of clinical symptoms. The management approach to these conditions is distinctly different. An abnormal iodine-123 ioflupane SPECT scan suggests a decreased amount of dopamine transporter in the striatum, that is, a diagnosis of nigrostriatal neurodegenerative PS, whereas a normal scan suggests ET or other nondegenerative parkinsonism (drug-induced, vascular, or psychogenic).

OBJECTIVE. The purpose of this perspective is to discuss the use of deformable registration as a tool for image fusion to integrate information from PET/CT scans obtained before and after chemotherapy to assist definition of radiation targets in the management of head and neck cancer. CONCLUSION. The consistent method for target delineation described capitalizes on the capability of deformable registration to compensate for changes in position and accurately represent evolving spatial relationships between normal anatomy and areas at risk of disease.

Case report from JAMA Otolaryngology–Head & Neck Surgery — Radiology Quiz Case 2

In intensity-modulated radiation therapy (IMRT), precise target delineation is important to avoid underdosing areas at risk for recurrence and overdosing adjacent normal tissue. In postoperative radiation therapy of patients with head and neck cancer (HNC), surgical extirpation of tumor, anatomic changes resulting from tissue removal, and surgical reconstruction often obscure anatomic detail and may make it difficult to identify high-risk target volumes at postoperative planning computed tomography (CT). Positron emission tomography (PET)/CT can significantly affect CT-based tumor contours by providing information on both biologic and metabolic features of cancer. To incorporate diagnostic PET/CT into target delineation at postoperative CT, an advanced image registration method is required to overcome significant differences in patient position and anatomy between the imaging studies. Rigid registration can account for only linear or uniform transformation between the imaging datasets within six degrees of freedom (three rotations and three translations). However, deformable registration can account for significant temporal and anatomic changes between the corresponding images by computing nonlinear and nonuniform relationships between the volume elements across the imaging datasets. Use of deformable registration to integrate preoperative PET/CT with postoperative treatment planning CT is a powerful tool for target volume delineation in HNC patients undergoing postoperative IMRT.

Background Interobserver agreement in measuring positron emission tomography (PET)/computed tomography (CT) parameters is critical for head and neck cancer management. The purpose of this study is to assess the interobserver agreement when measuring the standardized uptake value (SUV) parameters and the diameter of primary head and neck tumors between readers with varied experience in PET/CT. Methods PET/CT images of 47 patients (59.8±10.6 years, range 26–86 years) with head and neck cancer who had a baseline PET/CT at our institution (January 2007–May 2009) were retrieved and independently reviewed by four readers with varying experience reading PET/CT. Novice reader 1 was a preinternship medical student; novice reader 2 was a fourth-year radiology resident; expert reader 1 was a board-certified radiologist with a nuclear radiology fellowship and a junior faculty; and expert reader 2 was a dual radiology and nuclear medicine board-certified radiologist and a senior faculty. Intraclass correlation coefficients (ICCs) were estimated separately across novice and expert readers, between novice 1 and expert 1, and between novice 2 and expert 1 readers. Results The ICCs (95% confidence interval) for primary tumor diameter, primary tumor SUV_max, and primary tumor SUV_max normalized to liver SUV_mean within novices were 0.36 (0.09–0.59) (slight agreement), 0.60 (0.38–0.80) (fair agreement), and 0.91 (0.84–0.94) (almost perfect agreement), respectively. ICCs within experts were 0.84 (0.73–0.90) (almost perfect agreement), 0.91 (0.84–0.94) (almost perfect agreement), and 0.91 (0.84–0.95) (almost perfect agreement), respectively. The ICCs between novice 1 and experts are lower than those between novice 2 and experts for all parameters, and this disparity is greater for anatomic diameter than for fluorodeoxyglucose metabolic parameters. Conclusion Fluorodeoxyglucose metabolic parameters have higher interobserver agreement than anatomic diameter measurement and are more robust in the setting of varied reading experiences.

OBJECTIVE. The purpose of this article is to establish 18F-FDG metabolic imaging parameters to differentiate benign and malignant tumors of the parotid gland. MATERIALS AND METHODS. Forty-nine patients with increased FDG uptake in the parotid gland were selected for the study group (29 men and 20 women; mean age, 63.14 ± 12.32 years). Another 49 patients without head and neck malignancies were selected as the control group (24 men and 25 women; mean age, 65.80 ± 11.51 years); they did not have a parotid lesion or increased FDG uptake in the parotid gland. Maximum standardized uptake value (SUVmax) was obtained for all patients. Metabolic tumor volume and total glycolytic activity were measured in patients with a discrete parotid lesion (n = 24). Nonparameteric Student t test (Mann-Whitney U test) was performed for between-group analysis. RESULTS. The median SUVmax of the increased diffuse uptake (2.55; interquartile range [IQR], 1.03–4.07) was significantly lower than the median SUVmax of tumors (8.48; IQ...

OBJECTIVE. The purpose of this article is to establish whether pretreatment ¹⁸F-FDG uptake predicts disease-free survival (DFS) and overall survival in patients with head-and-neck non–squamous cell carcinoma (SCC). MATERIALS AND METHODS. Eighteen patients (six women and 12 men; mean [± SD] age at diagnosis, 57.89 ± 13.54 years) with head-and-neck non-SCC were included. Tumor FDG uptake was measured by the maximum standardized uptake value (SUV_max) and was corrected for background liver FDG uptake to derive the corrected SUV_max. Receiver operating characteristic analyses were used to predict the optimal corrected SUV_max cutoffs for respective outcomes of DFS (i.e., absence of recurrence) and death. RESULTS. The mean corrected SUV_max of the 18 head-and-neck tumors was 5.63 ± 3.94 (range, 1.14–14.29). The optimal corrected SUV_max cutoff for predicting DFS and overall survival was 5.79. DFS and overall survival were significantly higher among patients with corrected SUV_max < 6 than among patients with corrected SUV_max ≥ 6. The mean DFS for patients with corrected SUV_max < 6 was 25.7 ± 11.14 months, and the mean DFS for patients with corrected SUV_max ≥ 6 was 7.88 ± 7.1 months (p < 0.018). Among patients with corrected SUV_max < 6, none died, and the mean length of follow-up for this group was 35.2 ± 9.96 months. All of the patients who died had corrected SUV_max ≥ 6, and the overall survival for this group was 13.28 ± 12.89 months (p < 0.001). CONCLUSION. FDG uptake, as measured by corrected SUV_max, may be a predictive imaging biomarker for DFS and overall survival in patients with head-and-neck non-SCC.

OBJECTIVE. This article will discuss the 18F-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.