In tumor response monitoring studies with 18F-FDG PET, maximum standardized uptake value (SUVmax) is commonly applied as a quantitative metric. Although it has several advantages due to its simplicity of determination, concerns about the influence of image noise on single-pixel SUVmax persist. In this study, we measured aspects of bias and reproducibility associated with SUVmax and the closely related peak SUV (SUVpeak) using real patient data to provide a realistic noise context. Methods List-mode 3-dimensional PET data were acquired for 15 min over a single bed position in twenty 18F-FDG oncology patients. For each patient, data were sorted so as to form 2 sets of images: respiration-gated images such that each image had statistical quality comparable to a 3 min/bed position scan, and 5 statistically independent (ungated) images of different durations (1, 2, 3, 4, and 5 min). Tumor SUVmax and SUVpeak (12-mm-diameter spheric region of interest positioned so as to maximize the enclosed average) were analyzed in terms of reproducibility and bias. The component of reproducibility due to statistical noise (independent of physiologic and other variables) was measured using paired SUVs from 2 comparable respiration-gated images. Bias was measured as a function of scan duration. Results Replicate tumor SUV measurements had a within-patient SD of 5.6% ± 0.9% for SUVmax and 2.5% ± 0.4% for SUVpeak. SUVmax had average positive biases of 30%, 18%, 12%, 4%, and 5% for the 1-, 2-, 3-, 4-, and 5-min images, respectively. SUVpeak was also biased but to a lesser extent: 11%, 8%, 5%, 1%, and 4% for the 1-, 2-, 3-, 4-, and 5-min images, respectively. Conclusion The advantages of SUVmax are best exploited when PET images have a high statistical quality. For images with noise properties typically associated with clinical whole-body studies, SUVpeak provides a slightly more robust alternative for assessing the most metabolically active region of tumor.

Purple urine bag syndrome (PUBS) is a unique disease entity characterized by an alarming purple discoloration of the urine secondary to recurrent urinary tract infections with indigo- and indirubin-producing bacteria. It is usually associated with prolonged urinary catheterization and chronic debilitated states. We hereby present a concise review of this rare phenomenon with historic perspectives, epidemiology, emphasizing on current concepts of etiology, pathogenesis, relevant clinical associations, treatment modalities, prognosis, and future directions in PUBS. In addition, we highlight an interesting occurrence of this intriguing phenomenon in a 39-year-old gentleman at our institution.

Purpose Although previous studies have demonstrated the prognostic value of positron emission tomography (PET) parameters in other malignancies, the role of PET in pancreatic cancer has yet to be well established. We analyzed the prognostic utility of PET for patients with locally advanced pancreatic cancer (LAPC) undergoing fractionated stereotactic body radiation therapy (SBRT). Materials and Methods Thirty-two patients with LAPC in a prospective clinical trial received up to 3 doses of gemcitabine, followed by 33 Gy in 5 fractions of 6.6 Gy, using SBRT. All patients received a baseline PET scan prior to SBRT (pre-SBRT PET). Metabolic tumor volume (MTV), total lesion glycolysis (TLG), and maximum and peak standardized uptake values (SUVmax and SUVpeak) on pre-SBRT PET scans were calculated using custom-designed software. Disease was measured at a threshold based on the liver SUV, using the equation Livermean + [2 × Liversd]. Median values of PET parameters were used as cutoffs when assessing their prognostic potential through Cox regression analyses. Results Of the 32 patients, the majority were male (n = 19, 59%), 65 years or older (n = 21, 66%), and had tumors located in the pancreatic head (n = 27, 84%). Twenty-seven patients (84%) received induction gemcitabine prior to SBRT. Median overall survival for the entire cohort was 18.8months (95% confidence interval [CI], 15.7–22.0). An MTV of 26.8 cm3 or greater (hazard ratio [HR] 4.46, 95% CI 1.64–5.88, P<.003) and TLG of 70.9 or greater (HR3.08,95%CI 1.18–8.02,P<.021) on pre-SBRT PET scan were associated with inferior overall survival on univariate analysis. Both pre-SBRT MTV (HR 5.13, 95% CI 1.19–22.21, P = .029) and TLG (HR 3.34, 95% CI 1.07–10.48, P = .038) remained independently associated with overall survival in separate multivariate analyses. Conclusions Pre-SBRT MTV and TLG are potential predictive factors for overall survival in patients with LAPC and may assist in tailoring therapy.

The coronary slow flow phenomenon (CSFP) is a disease entity characterized by slow progression of angiographic contrast in the coronary arteries in the absence of stenosis in the epicardial vessels. CSFP has a diverse presentation from mild chest discomfort to ST-segment elevation myocardial infarction. It can also have severe morbidity and mortality implications and can significantly hamper the quality of life of those affected. In this paper we present two patients with CSFP highlighting the diverse spectrum of presentation. A concise review of the literature is also provided emphasizing the epidemiology, pathogenesis, diagnostic parameters, treatment modalities, and clinical significance of this phenomenon.