Magnetic resonance spectroscopy of hepatic lipid content and associated risk factors in HIV infection

BACKGROUND: Liver-related illness is increasingly recognized as a source of morbidity in HIV-infected patients. Fatty infiltration of the liver is potentially an important consequence of HIV and treatment with antiretroviral (ARV) therapy. OBJECTIVE: The aim of the present study was to evaluate HIV-infected men and women for hepatic steatosis using noninvasive magnetic resonance spectroscopy (MRS) and to assess the relationship between liver fat content, insulin resistance, and other associated risk factors. METHODS: We examined 33 consecutively recruited HIV-infected adults without specific referral for liver disease. Subjects with alcohol abuse within 3 years or end-stage liver disease were excluded. The primary clinical measures were hepatic fat content measured by MRS, homeostasis model for assessment of insulin resistance (HOMA-IR), and body fat distribution assessed by cross-sectional computed tomography. RESULTS: We identified hepatic steatosis (liver fat content > or =5%) in 42% of subjects. Hepatic fat content was significantly correlated with HOMA-IR (r = 0.68, P < 0.0001) and increased visceral adiposity (r = 0.60, P < 0.001). Subjects with steatosis had significantly increased body mass index and alanine aminotransferase and triglyceride levels, with lower muscle attenuation (ie, increased intramuscular fat) compared to subjects without steatosis. However, steatosis was not related to duration of HIV, ARV exposure, or HCV coinfection. CONCLUSIONS: These data suggest that hepatic steatosis may be very common in HIV, not limited to those with HCV coinfection, and may play an important role in the metabolic profile among HIV-infected men and women.     

Impact of low-energy CT imaging on selection of positive oral contrast media concentration

Abdominal Radiology - To determine to what extent low-energy CT imaging affects attenuation of gastrointestinal tract (GIT) opacified with positive oral contrast media (OCM). Second, to establish...     

Computed tomography perfusion imaging as a potential imaging biomarker of colorectal cancer

Neovascularization was reported to arise early in the adenoma-carcinoma sequence in colorectal cancer (CRC), and the importance of angiogenesis in cancer progression has been established. Computed tomography (CT) perfusion (CTP) based on high temporal resolution CT images enables evaluation of hemodynamics of tissue in vivo by modeling tracer kinetics. CTP has been reported to characterize tumor angiogenesis, and to be a sensitive marker for predicting recurrence or survival in CRC. In this review, we will discuss the biomarker value of CTP in the management of CRC patients.     

Effect of obesity on image quality: fifteen-year longitudinal study for evaluation of dictated radiology reports

PURPOSE: To retrospectively assess the effect of obesity on image quality, as determined from dictated radiology reports filed between 1989 and 2003. MATERIALS AND METHODS: Institutional review board approval was obtained for this HIPAA-compliant study; informed consent was not required. Electronic records were searched for radiology reports with the phrase "limited due to body habitus" (hereafter, "habitus limited") filed between 1989 and 2003; reports were retrospectively reviewed. Habitus limited was qualified as the search phrase by auditing radiologic images and patient weights. Trends in the number of habitus-limited reports were calculated for each year, and linear regression analysis was performed. The number of habitus-limited reports was also compared between modalities within a year and within each modality across 15 years. The trend was correlated with the prevalence of obesity in Massachusetts by using the Pearson correlation coefficient. RESULTS: There was a significant difference (P < .001) between the weight of patients with habitus-limited reports and the weight of patients with reports that were not habitus limited. Overall, 7778 (0.15%) of 5 253 014 reports were habitus limited. Between 1989 and 2003, there was a linear increase of 0.010% per year (95% confidence interval: 0.007%, 0.013%; P < .001). There was a positive correlation between the increased number of habitus-limited reports and the increased prevalence of obese individuals in Massachusetts between 1991 and 2001. The modality most commonly associated with habitus-limited reports was abdominal ultrasonography. CONCLUSION: There was a small but progressive increase in the number of habitus-limited radiology reports between 1989 and 2003.     

Contrast-induced nephropathy in patients with chronic kidney disease undergoing computed tomography: a double-blind comparison of iodixanol and iopamidol

BACKGROUND: Based on a single clinical trial, it has been suggested that the contrast agent iodixanol, which is isotonic to human plasma, may be less nephrotoxic than other nonionic contrast agents in renally impaired patients after intra-arterial injection. We compared the effects on renal function of iopamidol-370 injection (796 mOsm/kg) and iodixanol-320 (290 mOsm/kg) in patients with chronic kidney disease undergoing contrast-enhanced multidetector computed tomography (CE-MDCT) examinations using a multicenter, double-blind, randomized, parallel-group design. METHODS: A total of 166 patients with stable moderate-to-severe chronic kidney disease (screening and baseline serum creatinine, SCr, > or =1.5 mg/dL and/or creatinine clearance, CrCl, < or =60 mL/min) who were undergoing CE-MDCT of the liver or peripheral arteries were randomized to receive equi-iodine IV doses (40 gI) of either iopamidol-370 (370 mgI/mL) or iodixanol-320 (320 mgI/mL) at 4 mL/s. SCr and CrCl were obtained at screening, baseline, and at 48-72 +/- 6 hours after dose (mean, 57.4 hours). Contrast-induced nephropathy (CIN) was defined as an absolute increase > or =0.5 mg/dL (44.2 micromol/L) and/or a relative increase in SCr > or =25% from baseline. RESULTS: A total of 153 patients were included in the final analysis (13 patients excluded because of lack of follow-up, hemodialysis to remove contrast, average daily CrCl variation >1% at screening). The 2 study groups were comparable with regard to age, gender distribution, the presence of diabetes, concomitant medications, hydration, and contrast dose. Mean predose SCr was 1.6 +/- 0.4 mg/dL in both groups (P = 0.9). An absolute increase > or =0.5 mg/dL (44.2 micromol/L) in SCr was observed in none of the patients receiving iopamidol-370 and in 2.6% (2/76) of patients receiving iodixanol-320 (95% confidence interval -6.2, 1.0, P = 0.2). A relative increase > or =25% in SCr occurred in 4% (3/77) of patients receiving iopamidol-370 and in 4% (3/76) of the patients receiving iodixanol-320 (95% confidence interval -6.2, 6.1, P = 1.0). CONCLUSION: The rate of CIN was similarly low in risk patients after intravenous administration of iopamidol-370 or iodixanol-320 for CE-MDCT.     

EUS-guided injection of paclitaxel (OncoGel) provides therapeutic drug concentrations in the porcine pancreas (with video)

BACKGROUND: OncoGel (ReGel/paclitaxel) is an intralesional injectable formulation of the chemotherapeutic drug, paclitaxel, for local tumor management. OBJECTIVE: The aim of this study was to determine if a minimally invasive EUS-guided injection of paclitaxel, bound to a thermosensitive gel carrier, would lead to therapeutic tissue concentrations of the chemotherapeutic agent in the porcine pancreas. DESIGN: Eight Yorkshire breed pigs were sedated by general anesthesia and OncoGel was injected, under EUS-guidance, with a 22-gauge needle into the tail of the pancreas. MAIN OUTCOME MEASUREMENTS: During the 7-day (n = 4) or 14-day (n = 4) observational period, the animals were monitored by serum levels of amylase and lipase, and by a CT on day 4. The outcome was determined by gross and microscopic evidence of inflammation of the pancreas, clinical tolerance, and quantitation of tissue paclitaxel concentrations. RESULTS: Eight pigs underwent injection of 1, 2, 3, or 4 mL OncoGel (6 mg paclitaxel per 1 mL OncoGel) (n = 2 per group). An intrapancreatic hyperechoic focus, with an average diameter of 2.1 +/- 0.8 cm, was visible by EUS, and a hypodense area in the tail of the pancreas was visible by contrast CT. Clinically, the animals appeared to tolerate the procedure without sequelae. Blood levels of amylase and lipase were normal. At euthanasia, a depot of OncoGel, with an average diameter of 14.7 +/- 5.0 mm), was located both grossly and histologically in the pancreatic tail. After 14 days, clinically significant tissue concentrations of paclitaxel were detected at a distance of 30 to 50 mm from the depot in the animals that underwent an injection of 3 and 4 mL of the agent (n = 2). CONCLUSIONS: The EUS-guided injection of OncoGel into the pancreas of the pig provided high and sustained localized concentrations of paclitaxel. This technique is a potential minimally invasive local treatment option for unresectable pancreatic tumors.     

New approaches for precise response evaluation in hepatocellular carcinoma

With the increasing clinical use of cytostatic and novel biologic targeted agents,conventional morphologic tumor burden assessments,including World Health Organization criteria and Response Evaluation Criteria in Solid Tumors,are confronting limitations because of their difficulties in distinguishing viable tumor from necrotic or fibrotic tissue.Therefore,the investigation for reliable quantitative biomarkers of therapeutic response such as metabolic imaging or functional imaging has been desired.In this review,we will discuss the conventional and new approaches to assess tumor burden.Since targeted therapy or locoregional therapies can induce biological changes much earlier than morphological changes,these functional tumor burden analyses are very promising.However,some of them have not gone thorough all steps for standardization and validation.Nevertheless,these new techniques and criteria will play an important role in the cancer management,and provide each patient more tailored therapy.     

Evaluation of the effects of oral water and low-density barium sulphate suspension on bowel appearance on FDG-PET/CT

The purpose of this study is to assess which of five bowel preparation regimes offers superior bowel distension and to assess if these regimes adversely affect FDG activity on PET/CT imaging. The study conformed to HIPAA regulations. Ninety patients were divided into five groups of 18 who received no oral contrast agent (group A); 900 ml of water orally (group B); or 900, 1,350, or 1,800 ml of LDB (groups C, D, E, respectively). PET/CT examinations were assessed quantitatively (bowel diameter, SUV) and qualitatively (visual assessment grading scale) for bowel distension and FDG activity by two blinded readers. ANOVA was utilized to determine if a statistically significant difference (SSD) existed between the groups in terms of distension and FDG uptake. Qualitatively superior bowel distension was observed in group C (LDB) compared to B (water) and greater distension was noted with increased volumes of LDB in C, D, and E. Quantitatively there was an SSD in mean distension between groups C and B (P?<?0.001 except duodenum). Qualitatively and quantitatively there was no significant difference in bowel FDG uptake among the groups (P?>?0.05). LDB as an oral contrast agent provides superior bowel distension over water and does not induce increased FDG bowel activity.     

Utility of positron emission tomography/CT in the evaluation of small bowel pathology

We describe the management principles and different roles of positron emission tomography (PET)/CT in the evaluation of patients with small bowel tumours (adenocarcinoma, gastrointestinal stromal tumour, lymphoma, metastases) from initial staging, monitoring response to treatment, to detection of recurrent disease. We also discuss the various non-malignant aetiologies of small bowel fludeoxyglucose (FDG) PET uptake, and other pitfalls in FDG PET/CT interpretation. Awareness of the imaging appearances of small bowel tumours, patterns of disease spread and potential PET/CT interpretation pitfalls are of paramount importance to optimise diagnostic accuracy.