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.

Imaging-based quantification of hepatic fat: methods and clinical applications.

Fatty liver disease comprises a spectrum of conditions (simple hepatic steatosis, steatohepatitis with inflammatory changes, and end-stage liver disease with fibrosis and cirrhosis). Hepatic steatosis is often associated with diabetes and obesity and may be secondary to alcohol and drug use, toxins, viral infections, and metabolic diseases. Detection and quantification of liver fat have many clinical applications, and early recognition is crucial to institute appropriate management and prevent progression. Histopathologic analysis is the reference standard to detect and quantify fat in the liver, but results are vulnerable to sampling error. Moreover, it can cause morbidity and complications and cannot be repeated often enough to monitor treatment response. Imaging can be repeated regularly and allows assessment of the entire liver, thus avoiding sampling error. Selection of appropriate imaging methods demands understanding of their advantages and limitations and the suitable clinical setting. Ultrasonography is effective for detecting moderate or severe fatty infiltration but is limited by lack of interobserver reliability and intraobserver reproducibility. Computed tomography allows quantitative and qualitative evaluation and is generally highly accurate and reliable; however, the results may be confounded by hepatic parenchymal changes due to cirrhosis or depositional diseases. Magnetic resonance (MR) imaging with appropriate sequences (eg, chemical shift techniques) has similarly high sensitivity, and MR spectroscopy provides unique advantages for some applications. However, both are expensive and too complex to be used to monitor steatosis.

Perfusion computed tomography for monitoring induction chemotherapy in patients with squamous cell carcinoma of the upper aerodigestive tract: correlation between changes in tumor perfusion and tumor volume.

OBJECTIVE: The aim of this study was to assess the potential of perfusion computed tomography (CTp) for monitoring induction chemotherapy in patients with squamous cell carcinoma (SCCA) of the upper aerodigestive tract. MATERIALS AND METHODS: Twenty-five patients with advanced SCCA underwent CTp and volumetric CT before and after induction chemotherapy. Perfusion CT parameters were calculated in the tumor, normal tissue, and muscles and correlated with tumor volume. RESULTS: The blood flow (BF), blood volume (BV), and permeability surface were significantly higher, and the mean transit time was significantly lower in the tumor than in the normal tissue. The tumor BF and BV significantly decreased, and the mean transit time significantly increased after the therapy; decrease in BF and BV correlated with tumor volume reduction after chemotherapy. The baseline tumor BV was significantly lower in nonresponders compared with that in responders. CONCLUSIONS: In patients with SCCA, CTp showed potential for monitoring induction chemotherapy, reduction in tumor BF and BV correlated with reduction of tumor volume after chemotherapy, and baseline tumor BV may predict response to chemotherapy.

Imaging techniques for adrenal lesion characterization.

Imaging of the adrenal gland for characterization of adrenal lesions has made tremendous strides and new technologies continue to evolve. This article highlights the anatomic and physiologic imaging principles that underpin current major adrenal imaging modalities and the new techniques becoming available. This article focuses primarily on incidental adrenal lesions, which are encountered more frequently with increasing use of imaging. This article concludes with a brief discussion of the role of adrenal biopsy, performed less frequently because of the success of these noninvasive adrenal imaging advances.

Optimal arterial phase imaging for detection of hypervascular hepatocellular carcinoma determined by continuous image capture on 16-MDCT.

OBJECTIVE: The purpose of this study is to estimate the optimal time delay before the initiation of arterial phase scanning for detection of hypervascular hepatocellular carcinoma (HCC) on 16-MDCT when a rapid bolus injection of contrast medium is administered. SUBJECTS AND METHODS: In this prospective study, 25 patients (19 men and six women; mean age, 63.5 years; age range, 50-81 years) with pathologically confirmed HCC were included. Dynamic 16-MDCT imaging was performed in cine mode using 70 mL of nonionic iodinated contrast medium (300 mg I/mL) at an injection rate of 7 mL/s. Four consecutive 5-mm-thick slices at the maximum diameter of the HCC were selected as the region of interest. Time-attenuation curves were generated by region of interest drawn on the aorta, tumor, and liver. Qualitative assessments of conspicuity for contrast medium wash-in, peak, and wash-out of aorta and tumor were performed. RESULTS: There were 108 arterial phase enhancing lesions (mean [+/-SD], 4.9 +/- 2.4 cm; range, 0.7-12.9 cm) in the 25 patients. The maximum Hounsfield value of aorta, tumor, and background liver parenchyma were 463.8 +/- 98 HU, 106.5 +/- 19 HU, and 98.3 +/- 14 HU, respectively. At the time of onset of peak tumor enhancement, the difference between tumor density and background liver density was 38.2 +/- 19 HU. The time-attenuation curve showed that the mean times of contrast enhancement start, peak, and end were 9.2 +/- 2.7 seconds, 19.4 +/- 2.1 seconds, and 38 +/- 13.5 seconds, respectively, for the aorta, and 15.5 +/- 2.6 seconds, 26.3 +/- 2.9 seconds, and 57.7 +/- 14.4 seconds, respectively, for 25 pathologically confirmed hepatocellular carcinomas. Qualitatively, the mean times of contrast enhancement wash-in, peak, and washout were 10.2 +/- 2.8 seconds, 19.9 +/- 3 seconds, and 39.9 +/- 9.2 seconds, respectively for the aorta, and 18 +/- 4.2 seconds, 27 +/- 3 seconds, and 55.7 +/- 21 seconds, respectively, for tumor. There were no differences between quantitative and qualitative measurements of wash-in and peak time for the aorta (p = 0.00017, p = 0.00016) and tumor (p = 0.00163, p = 0.00040). CONCLUSION: When using 70 mL of 300 mg I/mL of contrast medium with an injection rate of 7 mL/s in 16-MDCT scanning, the optimal time to initiate scanning for HCC is 26.3 +/- 2.9 seconds (range, 24.0-34.5 seconds) after contrast medium administration.

Cholangiocarcinoma: current and novel imaging techniques.

The radiologic manifestations of cholangiocarcinomas are extremely diverse, since these tumors vary greatly in location, growth pattern, and histologic type. Familiarity with the imaging manifestations of cholangiocarcinomas is important for accurate detection and characterization of these tumors and assessment of resectability. Advances in imaging techniques have led to the availability of an array of modalities that, used independently or in combination, can aid in the accurate diagnosis and evaluation of cholangiocarcinomas in preparation for advanced surgical procedures and treatment planning. Response to novel targeted therapies can also be assessed with newer imaging tools. Hence, knowledge of current and emerging imaging applications is essential for correct diagnosis and appropriate management of these tumors.

Dynamic-threshold level set method for volumetry of porcine kidney in CT images in vivo and ex vivo assessment of the accuracy of volume measurement.

RATIONALE AND OBJECTIVE: We sought to assess the accuracy of a novel computerized volumetry method, called dynamic-thresholding (DT) level set, in determining the renal volume of pigs in CT images on the basis of in vivo and ex vivo reference standards. METHODS AND MATERIALS: Eight Yorkshire breed anesthetized pigs (weight range 45-50 kg) were scanned on a 64-slice multidetector CT scanner (Sensation 64; Siemens) after injection of an iodinated (300 mg I/ml) contrast agent through an IV cannula. The kidneys of the pigs were then surgically resected and scanned by CT in the same manner. Both in vivo and ex vivo CT images were subjected to our computerized volumetry using DT level set method. The resulting volumes of the kidneys were compared with in vivo and ex vivo reference standards: the former was established by manual contouring of the kidneys on the CT images by an experienced radiologist, and the latter was established as the water displacement volume of the resected kidney. RESULTS: The comparisons of the in vivo and ex vivo measurements by our volumetric scheme with the associated reference standards yielded a mean difference of 1.73 +/- 1.24% and 3.38 +/- 2.51%, respectively. The correlation coefficients were 0.981 and 0.973 for in vivo and ex vivo comparisons, respectively. The mean difference between in vivo and ex vivo reference standards was 5.79 +/- 4.26%, and the correlation coefficient between the two standards was 0.760. CONCLUSION: Our computerized volumetry using the DT level set method can provide accurate in vivo and ex vivo measurements of kidney volume, despite a large difference between the two reference standards. This technique can be employed in human subjects for the determination of renal volume for preoperative surgical planning and assessment of oncology treatment.

State-of-the-art cross-sectional imaging in bladder cancer.

Advances in cross-sectional imaging have given radiology an increasingly significant role in the diagnosis, staging, and restaging of patients with bladder cancer. The primary role of computed tomography (CT) in bladder cancer is for tumor staging and screening for distant metastases. Multidetector-row CT may improve the evaluation of bladder tumors by overcoming the difficulties of previous generations of CT in detecting invasion of contiguous organs and nodal staging. Magnetic resonance imaging (MRI) however is still considered superior to CT for primary staging of bladder carcinoma. The multiplanar capability of MRI with its superior soft-tissue resolution offers improved evaluation of local staging of bladder tumors. Positron emission tomography/CT is emerging as a novel-imaging tool for the detection of distant metastases. In this review, we emphasize the value of current cross-sectional imaging and discuss the potential applications of novel imaging techniques in the management of patients with bladder cancer, predominantly transitional cell carcinoma.

Radiology 24/7 In-House Attending Coverage: Do Benefits Outweigh Cost?

Many radiology practices, including academic centers, are moving to in-house 24/7 attending coverage. This could be costly and may not be easily accepted by radiology trainees and attending radiologists. In this article, we evaluated the effects of 24/7 in-house attending coverage on patient care, costs, and qualitative aspects such as trainee education. We retrospectively collected report turnaround times (TAT) and work relative value units (wRVU). We compared these parameters between the years before and after the implementation of 24/7 in-house attending coverage. The cost to provide additional attending coverage was estimated from departmental financial reports. A qualitative survey of radiology residents and faculty was performed to study perceived effects on trainee education. There were decreases in report TAT following 24/7 attending implementation: 69% reduction in computed tomography, 43% reduction in diagnostic radiography, 7% reduction in magnetic resonance imaging, and 43% reduction in ultrasound. There was an average daytime wRVU decrease of 9%, although this was compounded by a decrease in total RVUs of the 2013 calendar year. The financial investment by the institution was estimated at $850,000. Qualitative data demonstrated overall positive feedback from trainees and faculty in radiology, although loss of independence was reported as a negative effect. TAT and wRVU metrics changed with implementation of 24/7 attending coverage, although these metrics do not directly relate to patient outcomes. Additional clinical benefits may include fewer discrepancies between preliminary and final reports that may improve emergency and inpatient department workflows and liability exposure. Radiologists reported the impression that clinicians appreciated 24/7 in-house attending coverage, particularly surgical specialists. Loss of trainee independence on call was a perceived disadvantage of 24/7 attending coverage and raised a concern that residency education outcomes could be adversely affected.

Imaging of miscellaneous pancreatic pathology (trauma, transplant, infections, and deposition).

In this article's coverage of miscellaneous pancreatic topics, a brief review of pancreatic trauma; pancreatic transplantation; rare infections, such as tuberculosis; deposition disorders, including fatty replacement and hemochromatosis; cystic fibrosis; and others are discussed with pertinent case examples.

Issues in imaging malignant neoplasms of the female reproductive system.

Radiological evaluation of malignant neoplasms of the female reproductive system is invaluable in the initial diagnosis, staging, treatment planning, and follow-up management. Radiologists serving as consultants for the general primary care internist, gynecologists, and specialists in gynecologic oncology should be familiar with the strengths and limitations of various modalities used to evaluate gynecologic cancer patients. This article discusses the most common female reproductive tract neoplasms (ie, cervical, endometrial, and ovarian cancers) and the role of ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography in their diagnosis and management. Imaging features that impact on clinical diagnostic or treatment algorithms are highlighted and illustrated. Finally, recent technical advances that demonstrate promise are described.

Role of computed tomography perfusion in the evaluation of pancreatic necrosis and pancreatitis after endoscopic ultrasound-guided ablation of the pancreas in a porcine model.

OBJECTIVES: To evaluate the role of computed tomography (CT) perfusion in detection of pancreatic necrosis and pancreatitis after endoscopic ultrasound-guided ethanol ablation of porcine pancreas and to correlate the evaluation with histopathology. METHODS: Under endoscopic ultrasound guidance, 0.9% saline (control) and ethanol at 60%, 80%, and 100% concentrations were injected into the pancreatic tails of 4 pigs. On day 4, dynamic perfusion CT of the pancreas was performed. Perfusion analysis and evaluation of enhancement characteristics were done and correlated with histopathology. RESULTS: Ethanol injections at 80% and 100% concentrations resulted in focal necrosis surrounded by focal pancreatitis, whereas 60% ethanol injection caused severe focal pancreatitis with microscopic necrosis. The necrotic area revealed reduced blood flow, blood volume, permeability-surface area product, and increased mean transit time compared with pancreatitis and normal tissue (P < or = 0.001). In the control pig, no pancreatitis or necrosis was observed on perfusion images and histopathology. CONCLUSIONS: Pancreatic necrosis and pancreatitis after ethanol injection reduced the tissue perfusion on CT in comparison to normal tissue, with the changes being more substantial in necrosis than pancreatitis. These findings have possible implications in the accurate detection of pancreatic necrosis in patients with severe pancreatitis.

Advanced hepatocellular carcinoma: CT perfusion of liver and tumor tissue--initial experience.

PURPOSE: To prospectively assess computed tomographic (CT) perfusion for evaluation of tumor vascularity of advanced hepatocellular carcinoma (HCC) and to correlate CT perfusion parameters with tumor grade and serum markers. MATERIALS AND METHODS: The study was HIPAA compliant and was approved by the institutional review board. Patients provided informed consent. Thirty patients (22 men, eight women; mean age, 60 years; range, 28-79 years) with unresectable or metastatic HCC were studied. Dynamic first-pass CT perfusion was performed in primary (n=25) and metastatic (n=5) HCCs after intravenous injection of contrast medium. Data were analyzed to calculate tissue blood flow, blood volume, mean transit time, and permeability-surface area product. Repeat examination was performed in four patients within 30 hours to test reproducibility of CT perfusion. CT perfusion parameters were compared among tumors of different grades, with presence or absence of portal vein invasion, with presence or absence of cirrhosis, and of various extrahepatic metastases. Parameters were correlated with HCC serum markers. One-way analysis of variance was used to calculate variations in CT perfusion parameters. RESULTS: Good correlation (r=0.9, P<.01) was observed between repeat examination results and first CT examination results. There was a significant difference (P

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.

Characterization of small liver lesions: Added role of MR after MDCT.

OBJECTIVE: The purpose of this study is to evaluate the added role of magnetic resonance imaging (MR) in characterizing subcentimeter focal liver lesion(s) detected on multidetector row helical computed tomography (MDCT). MATERIALS AND METHODS: A retrospective analysis was performed in 59 noncirrhotic patients with focal subcentimeter liver lesion(s) detected on a 4- or 16-slice MDCT. All patients had a gadolinium enhanced liver MR on 1.5-T systems within 6 weeks after MDCT. Imaging diagnosis was graded on an ordinal scale of 0-5 (0, normal; 1, definitely benign; and 5, definitely malignant). The final diagnosis was established either by histopathology or follow-up imaging for a period of at least 6 months. Receiver operating characteristic analysis was performed to compare the performances of MDCT and MR in characterization of subcentimeter liver lesions. RESULTS: A total of 178 lesions were detected on MDCT in 59 patients. Of these lesions, 129 (72.5%) lesions were benign and the remaining 49 were malignant. The sensitivity, specificity, positive predictive value, and negative predictive value in differentiation of benign from malignant lesions on MDCT were 81.2%, 77.3%, 60.5%, 90.6 % and on MR were 83.3%, 97.5%, 92.1%, and 94.4 %, respectively. Comparative receiver operating characteristic analysis showed an area under curve for MDCT = 0.76 and MR = 0.95 (P < 0.001). CONCLUSIONS: Liver MR has significantly higher accuracy for characterization of subcentimeter focal liver lesions discovered on MDCT.