Russ Kuker

Analysis of the Effects of Injecting Drug Use and HIV-1 Infection on 18F-FDG PET Brain Metabolism

Injecting drug use (IDU) is a major risk factor for contracting HIV-1 infection. Both HIV and IDU are neurotoxic, and their coexistence may lead to increased dysfunction of brain metabolic processes. The objective of this research was to investigate the effects of HIV-1 infection and IDU on 18F-FDG PET brain metabolism. Methods: 18F-FDG PET brain imaging, with a standard clinical protocol, was performed on 59 subjects who belonged to 3 groups: HIV-positive/IDU-positive (n = 17), HIV-negative/IDU-positive (n = 13), and HIV-negative/IDU-negative controls (n = 29). A voxel-based analysis of the 18F-FDG PET brain images was performed using statistical parametric mapping. The images were spatially normalized to a standard 18F-FDG template, proportionally scaled to compensate for count differences, and then appropriately smoothed. Statistical 2-sample t tests were performed to determine regional metabolic distribution differences in the 3 groups. Results: Diffuse hypermetabolism in the subcortical and deep white matter, the basal ganglia, and the thalami was observed in HIV-1 infection. IDU resulted in increased brainstem metabolism and decreased activity in cortical structures including bilateral medial frontal lobes and the right inferior frontal and temporal cortices. The cortical hypometabolism was more extensive in HIV-1–infected subjects, involving the left temporoparietal and right parietal cortices and bilateral medial frontal lobes. Conclusion: Voxel-based analysis of 18F-FDG PET brain images demonstrated statistically significant differences in regional metabolism for the 3 studied groups. It also showed that HIV-1 infection may have a synergistic effect with IDU, resulting in more extensive cortical hypometabolism. Correlation of these findings with other quantitative approaches and neurocognitive functioning is warranted.

Downhill esophageal varices: A prevalent complication of superior vena cava obstruction from benign and malignant causes

Objective Downhill esophageal varices (DEV) usually develop secondary to superior vena cava (SVC) obstruction. Downhill esophageal varices have been less well characterized compared to uphill varices. The aim of the study was to characterize the anatomy and etiology of DEV by contrast-enhanced computed tomography. Methods Patients with SVC obstruction were included in the study. Downhill esophageal varices were defined as discrete esophageal submucosal or mucosal vessels. Ten random computed tomographic scans were assessed as controls. Results Downhill esophageal varices were seen in 11 of 36 patients. Three types of varices were observed. Between 1 and 6 varices were seen in each patient with a diameter of 1 to 5 mm. Conclusions Downhill esophageal varices can be seen in 30% of patients with SVC obstruction. They have several patterns and are mostly systemic-to-systemic collaterals. The most common etiology associated with DEV is renal failure. Downhill esophageal varices are of small caliber, this may in part account for less frequent bleeding compared to uphill varices.

Superior Vena Cava Obstruction in Hemodialysis Patients: Symptoms, Clinical Presentation and Outcomes Compared to Other Etiologies

The incidence of superior vena cava (SVC) obstruction associated with non‐malignant diseases is on the rise, and a large percentage of these patients are on hemodialysis (HD). The objective was to characterize the presentation, symptoms and outcomes of HD patients with SVC obstruction identified on computerized tomography (CT) compared to patients with other etiologies such as neoplasm. A search was performed through the PACS system using key words to identify patients with SVC obstruction. The CT scans and charts were reviewed for degree of obstruction, signs, symptoms and outcomes. Thirty‐six patients were included in the study. Thirteen were on HD and of these, five had symptoms associated with SVC obstruction and one had concordant findings on physical exam. In comparison, thirteen patients with a chest neoplasm had symptoms and four had concordant findings on physical exam. On follow up, 31% of the HD patients died and of these 60% were symptomatic and died within 2 years. 29% of lung cancer patients died within 16 months. The majority of the HD patients had complete SVC obstruction (85%) as opposed to those with a chest neoplasm who mostly had partial SVC occlusion (67%). In conclusion, patients on HD with SVC obstruction are less often symptomatic than those with a neoplasm. However, these HD patients had a death rate similar to the patients with cancer. This risk seems to increase in those who are symptomatic. Diagnosis of SVC obstruction by CT in HD patients may help identify those with less favorable prognosis.

False Positive Findings on I-131 WBS and SPECT/CT in Patients with History of Thyroid Cancer: Case Series

Introduction. Although whole body scan (WBS) with I-131 is a highly sensitive tool for detecting normal thyroid tissue and metastasis of differentiated thyroid cancer (DTC), it is not specific. Additional information, provided by single photon emission computed tomography combined with X-ray computed tomography (SPECT/CT) and by the serum thyroglobulin level, is extremely useful for the interpretation of findings. Case Presentation. We report four cases of false positive WBS in patients with DTC: ovarian uptake corresponding to an endometrioma, scrotal uptake due to a spermatocele, rib-cage uptake due to an old fracture, and hepatic and renal uptake secondary to a granuloma and simple cyst, respectively. Conclusions. Trapping, organification, and storage of iodine are more prominent in thyroid tissue but not specific. Physiologic sodium-iodine symporter expression in other tissues explains some, but not all, of the WBS false positive cases. Other proposed etiologies are accumulation of radioiodine in inflamed organs, metabolism of radiodinated thyroid hormone, presence of radioiodine in body fluids, and contamination. In our cases nonthyroidal pathologies were suspected since the imaging findings were not corroborated by an elevated thyroglobulin level, which is considered a reliable tumor marker for most well-differentiated thyroid cancers. Clinicians should be aware of the potential pitfalls of WBS in DTC to avoid incorrect management.

Pancreatocolonic fistulization secondary to pancreatic adenocarcinoma presenting as unexplained halitosis

Pancreatic cancer is often detected in late stages, which contributes to its grim prognosis. Although the manifestations of pancreatic cancer most often include nonspecific gastrointestinal complaints, we report a case with the sole initial complaint of halitosis and subsequent diagnostic workup demonstrating a pancreatic mass with secondary pancreatocolonic fistulization. The etiologies of and the radiological findings pertaining to halitosis, the presenting symptoms and imaging studies relevant to the diagnosis of pancreatic cancer, and the imaging and clinical findings of pancreatic fistulization are discussed.

Occult Lung Cancer Occluding a Pulmonary Vein with Suspected Venous Infarction, Mimicking Pneumonia and a Pulmonary Embolus

BACKGROUND Patients with lung cancer present to the emergency department (ED) in a variety of ways. Symptoms are often nonspecific and can lead to a delay in diagnosis. Here, a lung cancer mimicked two illnesses, adding to the diagnostic complexity. This case highlights diagnostic pitfalls as well as advantages and limitations of imaging utilized in the emergency setting. CASE REPORT We report a case of an occult lung cancer occluding a pulmonary vein, which at first mimicked pneumonia and later a pulmonary embolism (PE) and arterial lung infarction. The patient presented to the ED with cough and a lung opacity on chest radiograph that was treated with antibiotics. However, recurrent visits to the ED with similar complaints were further investigated with computed tomography angiogram (CTA). At first the scan was considered positive for PE. Further inspection revealed that the CTA findings were not typical for PE, but rather a slow flow state likely caused by an occult mass occluding a pulmonary vein with venous infarction. Biopsy revealed a lung adenocarcinoma. In addition to the case presentation, the typical signs of PE on CTA with correlating images and diagnostic pitfalls are discussed. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case report raises two themes that can be of interest to emergency physicians. The first is that lung cancer has many guises. Here it mimicked two distinctly different diseases, pneumonia and PE. The second is that, although CTA is highly sensitive and specific for diagnosing PE, it has limitations that may lead to false positive readings. When clinical signs and symptoms fail to correlate with the imaging diagnosis, alternative explanations should be sought.

Quantitation of Metabolic Change in Serial FDG-PET Brain Scans of Pediatric Patients with Traumatic Brain Injury

The aim of this research was to develop a method to quantitate the changes in regional brain metabolism on serial FDG-PET scans in children with Traumatic Brain Injury (TBI) in order to determine their response to treatment with psycho stimulant medication. Methods: A Fusion-Based Image Subtraction (FBIS) technique was developed in order to calculate the differences in metabolism between baseline and follow-up scans. The FDG-PET brain images were count normalized to account for differences in the injected activity. Image registration was then performed using a 3D normalized mutual information algorithm and subsequently the fused images were subtracted on a pixel by pixel basis. FBIS extracted areas of increased or decreased metabolism were then compared to a database of normal subjects using NeuroQ (Syntermed, Inc.) and analyzed for statistical significance in cluster areas defined by a standard brain template. Results: Validation of the technique was performed using images from 15 pediatric cases with severe TBI who had baseline (pre-treatment) and follow-up (post-treatment) scans. The FBIS technique was found to be accurate in detecting and localizing the statistically significant changes in regional cerebral metabolism and provided useful data that could be applied clinically. Conclusions: The developed FBIS method identified and quantified areas of regional brain metabolic change thus providing a way to evaluate the effects of pharmacologic treatment in children with TBI. This quantitative technique could be used as an adjunct tool to enhance the interpretation of FDG-PET brain images and aid the referring clinician to assess the response to pharmacologic treatment.