Characterization of Thyroid Nodules by 4-Dimensional Computed Tomography: Initial Experience.

OBJECTIVE: We aimed to evaluate the use of 4-dimensional computed tomography (4DCT) for characterization of thyroid nodules. METHODS: Our study drew from 100 consecutive patients with primary hyperparathyroidism who underwent 4D parathyroid CT imaging for adenoma localization. Included subjects had tissue sampling of a thyroid nodule within 3 months of 4DCT. RESULTS: Twenty subjects (18 women and 2 men) had thyroid nodules that were pathologically confirmed. Precontrast nodule attenuation was significantly lower in malignant nodules when compared with benign nodules (36 vs 61 HU, P = 0.05). Arterial phase and delayed phase nodule attenuations were not significantly different in malignant and benign nodules (128 vs 144 HU, P = 0.7; 74 vs 98 HU, P = 0.3). CONCLUSIONS: Our initial experience with a small group of patients was unable to support the use of 4DCT for characterizing thyroid nodules; however, precontrast nodule attenuation was significantly lower in malignant nodules when compared with benign nodules.

Incidental mastoid opacification in children on MRI.

BACKGROUND: The opacification the mastoid cavity is frequently reported by radiologists on cross-sectional imaging done for non-otological indications. It is well known that presence of fluid the mastoid does not amount to mastoiditis. This study seeks to provide an evidence-based confirmation of this known finding. OBJECTIVE: The purpose of our study was to determine the prevalence of mastoid opacification in children undergoing outpatient brain MRI examination. MATERIALS AND METHODS: Our study included 515 outpatient children who had brain MRI for indications other than mastoiditis or otitis media from January 2014 to March 2014. Children with history of skull base trauma or radiation were excluded. The age range was 15 days to 18 years. The overall prevalence of mastoid opacification was determined using one sample proportion and exact 95% Clopper-Pearson confidence intervals. The prevalence of mastoid opacification was analyzed based on gender, age and presenting symptoms using chi-square test of association. RESULTS: One hundred ten children (21.4%) had mastoid opacification. Younger patients tended to have higher opacification rates with the prevalence in children younger than 1 year of age and between 1 and 2 years of age as high as 41.7% (20/48) and 47.5% (38/80), respectively. CONCLUSION: The diagnosis of mastoiditis in children should not be based upon a radiologist's report of finding fluid or mucosal thickening in the mastoid air cells as incidental opacification the mastoid is seen frequently.

Clinical Applications of Magnetic Resonance Spectroscopy in Brain Tumors: From Diagnosis to Treatment.

Magnetic resonance spectroscopy (MRS) is a valuable tool for imaging brain tumors, primarily as an adjunct to conventional imaging and clinical presentation. MRS is useful in initial diagnosis of brain tumors, helping differentiate tumors from possible mimics such as metastatic disease, lymphoma, demyelination, and infection, as well as in the subsequent follow-up of patients after resection and chemoradiation. Unfortunately, the spectroscopic appearance of many pathologies can overlap, and ultimately follow-up or biopsy may be required to make a definitive diagnosis. Future developments may continue to increase the value of MRS for initial diagnosis, treatment planning, and early detection of recurrence.

PET and SPECT Imaging of Epilepsy: Technical Considerations, Pathologies, and Pitfalls.

Epilepsy is generated by a plethora of varying pathologies, structural lesions, and pathways and may significantly impact a patient's livelihood. The combination of clinical semiology, electroencephalogram, and magnetic resonance imaging often fails to identify a structural seizure focus. The addition of functional radionuclide imaging is complementary to structural imaging and essential when structural imaging is discordant or inconclusive. The understanding of the key radiopharmaceuticals, imaging techniques, spectrum of disease processes, and potential pitfalls is necessary for diagnosis and surgical planning in epilepsy.

Gossypiboma of Axilla: Imaging Pitfalls on Fluorodeoxyglucose Positron Emission Tomography and Computed Tomography.

18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT) has become the standard of care in staging, restaging, and response assessment of various malignancies including malignant melanoma. However, nonspecific uptake of FDG can occur in infectious and inflammatory conditions and can mimic a tumor. We present here a case of gossypiboma of the axillary region with FDG uptake detected in a patient with malignant melanoma of the upper extremity and discuss the potential pitfalls of this entity on FDG-PET/CT.

111In-Pentetreotide Imaging in Diffuse Idiopathic Neuroendocrine Hyperplasia of the Lung.

Diffuse idiopathic endocrine neoplasia of the lung (DIPNECH) is a rare disease characterized by proliferation of neuroendocrine cells in the bronchial wall. Less than 20 cases of DIPNECH have been reported in imaging literature. We present here a case of histopathologically diagnosed DIPNECH with diffusely increased In-octreotide uptake in both lungs.

Multivariate analysis of various factors affecting background liver and mediastinal standardized uptake values.

PURPOSE OF THE STUDY: Standardized uptake value (SUV) is the most commonly used semi-quantitative PET parameter. Various response assessment criteria grade the tumor uptake relative to liver or mediastinal uptake. However various factors can affect the background SUV values. This prospective study was carried out to assess the variability of liver and mediastinal SUVs normalized to lean body mass (SUL-L, SUL-M), body surface area (SUB-L, SUB-M), and body weight (SUW-L, SUW-M) and their dependence on various factors which can affect SUV values. MATERIALS AND METHODS: Eighty-eight patients who underwent F-18 FDG PET/CT for various oncological indications were prospectively included in this study. SUVs of liver and mediastinum were calculated by ROIs drawn as suggested by Wahl, et al., in PERCIST 1.0 criteria. Multivariate linear regression analysis was done to assess for the various factors influencing the SUVs of liver and mediastinum. Factors assessed were age, sex, weight, blood glucose level, diabetic status, and uptake period. A P value less than 0.01 was considered significant. RESULTS: SUL-L, SUL-M, SUB-L, SUB-M, SUW-L, SUW-M were not affected significantly by age, sex, blood glucose levels, diabetic status. The uptake period had a statistically significant effect on SUL-L (P = 0.007) and SUW-L (P = 0.008) with a progressive decrease with increasing uptake time. Body weight showed a statistically significant effect on SUW-L (P = 0.001) while SUL-L and SUB-L were not dependent on weight. SUB-L was least dependent on weight (P = 0.851) when compared with SUL-L (P = 0.425). However SUL-L was also not affected statistically significantly by variations in body weight (P = 0.425). Mediastinal SUVs were not significantly affected by any of the factors. CONCLUSIONS: As mediastinal SUVs are not affected significantly by any of the factors, it can be considered as background when wide variations occur in uptake times or weight of the patient when comparing two PET/CT studies to evaluate response.

Bilateral retinoblastoma presenting as metastases to forearm bones four years after the initial treatment.

Osseous metastases from retinoblastoma, the most common ocular malignant neoplasm of childhood, are reported most commonly in the skull and long bones. However, metastases to forearm bones are very rare. Here we present a case of bilateral retinoblastoma with metastases to right forearm bones four years after the initial treatment.