New imaging techniques have been developed with the objective of obtaining not only a structural assessment, but also a metabolic and functional analysis of different organs and types of lesions. Among such tools perfusion computed tomography (PCT) has recently aroused the interest of many researchers in studying the applicability of such imaging modality in the evaluation of abdominal organs and diseases. Analysis of the biological behavior of healthy and diseased tissues, differentiation of inflammatory processes from tumors, and diagnosis of tumor recurrence after minimally invasive therapies can be mentioned as applications of such an imaging modality. The main features of PCT are related to its ability to characterize different perfusional behaviors reflecting biological changes of certain lesions and diseased tissues. Thus, the present study was aimed at carrying out a comprehensive literature review, describing the key techniques and protocols utilized in PCT imaging, main clinical applications, advantages and disadvantages of the method, besides proposing an imaging protocol that can be adopted by both private and public health services, with good reproducibility and easy implementation.

Keywords: Perfusion; Computed tomography; Biomarkers; Angiogenesis; Neoplasm; Contrast media.

OBJECTIVE: The purpose of this study was to assess the performance of neutral oral contrast agents, comparing intestinal distention, distinction of intestinal wall, acceptance and side effects. MATERIALS AND METHODS: Prospective, randomized, and double-blinded study involving 30 patients who underwent computed tomography of abdomen and pelvis with administration of neutral oral contrast agents, divided into three groups according the contrast agent type: milk, water, and polyethylene glycol. The images were consensually analyzed by two observers, considering the degree of bowel distention and intestinal wall distinction. The patients responded to a questionnaire regarding the taste of the ingested solution and on their side effects. Kruskal-Wallis and chi-square tests were employed for statistical analysis. RESULTS: Among 40 studied intestinal segments, appropriate bowel distension (intestinal loop diameter > 2 cm) was observed in 14 segments (35%) in the milk group, 10 segments (25%) in the water group and 23 segments (57%) in the polyethylene glycol group (p = 0.01). Preparation with polyethylene glycol resulted in the best bowel distention, but it presented the worst taste and highest incidence of diarrhea as reported by patients. CONCLUSION: Bowel preparation with oral polyethylene glycol results in higher degree of bowel distention than with water or milk, but presents worst acceptance related to its taste and frequency of diarrhea as a side effect.

Keywords: X-ray computed tomography; Small bowel; Contrast media.

OBJECTIVE: To assess the impact of oral ranitidine on the imaging quality in magnetic resonance cholangiopancreatography (MRCP). MATERIALS AND METHODS: Thirty-two patients underwent MRCP with 3D and 2D acquisitions, and three strategies for suppression of the gastrointestinal fluid signal: a) only at fasting; b) 12 hours after ingestion of 300 mg ranitidine; c) after oral administration of gadolinium solution. Three observers reviewed the images with a focus on the degree of visualization of the biliopancreatic tree. The interobserver agreement was evaluated with the kappa test. The difference between techniques and acquisition modalities were evaluated by means of average grading scores. RESULTS: The three strategies for suppression of the gastrointestinal fluid signal presented high reproducibility. The results with suppression of the gastrointestinal fluid signal with ranitidine where similar to those obtained with fasting, and both were worse than those obtained with gadolinium solution. The 3D acquisitions surpassed 2D only in terms of visibility of the cystic duct and gallbladder, and were inferior or equivalent in the other biliopancreatic ductal segments. CONCLUSION: The use of ranitidine does not seem justified in the evaluation of the biliopancreatic tree at MRCP, since 2D MRCP with fasting allows the visualization of ductal structures with high quality and reproducibility in the majority of cases.

Keywords: Ranitidine; Diagnostic use; Magnetic resonance cholangiopancreatography; Contrast media; Bile ducts; Pancreatic ducts.

OBJECTIVE: To evaluate the role of the equilibrium phase in abdominal computed tomography. MATERIALS AND METHODS: A retrospective, cross-sectional, observational study reviewed 219 consecutive contrast-enhanced abdominal computed tomography images acquired in a three-month period, for different clinical indications. For each study, two reports were issued - one based on the initial analysis of non-contrast-enhanced, arterial and portal phases only (first analysis), and a second reading of these phases added to the equilibrium phase (second analysis). At the end of both readings, differences between primary and secondary diagnoses were pointed out and recorded, in order to measure the impact of suppressing the equilibrium phase on the clinical outcome for each of the patients. The extension of the exact Fisher's test was utilized to evaluate the changes in the primary diagnosis (p < 0.05 as significant). RESULTS: Among the 219 cases reviewed, the absence of the equilibrium phase determined change in the primary diagnosis in only one case (0.46%; p > 0.999). As regards secondary diagnoses, changes after the second analysis were observed in five cases (2.3%). CONCLUSION: For clinical scenarios such as cancer staging, acute abdomen and investigation for abdominal collections, the equilibrium phase is dispensable and does not offer any significant diagnostic contribution.

Keywords: X-ray computed tomography; Ionizing radiation; Neoplasm staging; Acute abdomen.

OBJECTIVE: To evaluate the necessity of the non contrast-enhanced phase in abdominal computed tomography scans. MATERIALS AND METHODS: A retrospective, cross-sectional, observational study was developed, evaluating 244 consecutive abdominal computed tomography scans both with and without contrast injection. Initially, the contrast-enhanced images were analyzed (first analysis). Subsequently, the observers had access to the non-contrast-enhanced images for a second analysis. The primary and secondary diagnoses were established as a function of the clinical indications for each study (such as tumor staging, acute abdomen, investigation for abdominal collection and hepatocellular carcinoma, among others). Finally, the changes in the diagnoses resulting from the addition of the non-contrast-enhanced phase were evaluated. RESULTS: Only one (0.4%; p > 0.999; non-statistically significant) out of the 244 reviewed cases had the diagnosis changed after the reading of non-contrast-enhanced images. As the secondary diagnoses are considered, 35 (14%) cases presented changes after the second analysis, as follows: nephrolithiasis (10%), steatosis (3%), adrenal nodule (0.7%) and cholelithiasis (0.3%). CONCLUSION: For the clinical indications of tumor staging, acute abdomen, investigation of abdominal collections and hepatocellular carcinoma, the non-contrast-enhanced phase can be excluded from abdominal computed tomography studies with no significant impact on the diagnosis.

Keywords: Computed tomography; Ionizing radiation; Abdomen; Contrast media.

OBJECTIVE: To assess the reduction of estimated radiation dose in abdominal computed tomography following the implementation of new scan protocols on the basis of clinical suspicion and of adjusted images acquisition parameters. MATERIALS AND METHODS: Retrospective and prospective review of reports on radiation dose from abdominal CT scans performed three months before (group A - 551 studies) and three months after (group B - 788 studies) implementation of new scan protocols proposed as a function of clinical indications. Also, the images acquisition parameters were adjusted to reduce the radiation dose at each scan phase. The groups were compared for mean number of acquisition phases, mean CTDI_vol per phase, mean DLP per phase, and mean DLP per scan. RESULTS: A significant reduction was observed for group B as regards all the analyzed aspects, as follows: 33.9%, 25.0%, 27.0% and 52.5%, respectively for number of acquisition phases, CTDI_vol per phase, DLP per phase and DLP per scan (p < 0.001). CONCLUSION: The rational use of abdominal computed tomography scan phases based on the clinical suspicion in conjunction with the adjusted images acquisition parameters allows for a 50% reduction in the radiation dose from abdominal computed tomography scans.

Keywords: Computed tomography; Abdomen; Contrast media; Radiation dose; Radiation protection.

OBJECTIVE: To assess the impact that examiner experience has on the reproducibility and accuracy of computed tomography (CT) enterography in the detection of radiological signs in patients with Crohn’s disease. MATERIALS AND METHODS: This was a retrospective, cross-sectional observational study involving the analysis of CT enterography scans of 20 patients with Crohn’s disease. The exams were analyzed independently by two radiologists in their last year of residence (duo I) and by two abdominal imaging specialists (duo II). The interobserver agreement of each pair of examiners in identifying the main radiological signs was calculated with the kappa test. The accuracy of the examiners with less experience was quantified by using the consensus among three experienced examiners as a reference. RESULTS: Duo I and duo II obtained a similar interobserver agreement, with a moderate to good correlation, for mural hyperenhancement, parietal thickening, mural stratification, fat densification, and comb sign (kappa: 0.45–0.64). The less experienced examiners showed an accuracy > 80% for all signs, except for lymph nodes and fistula, for which it ranged from 60% to 75%. CONCLUSION: Less experienced examiners have a tendency to present a level of interobserver agreement similar to that of experienced examiners in evaluating Crohn’s disease through CT enterography, as well as showing satisfactory accuracy in identifying most radiological signs of the disease.

Keywords: Reproducibility of results; Crohn disease; Tomography, X-ray computed.

OBJECTIVE: To determine the average productivity of radiologists, as measured by number of reports issued per 6-h shift, evaluating variables that could affect the results. MATERIALS AND METHODS: This was a study utilizing an online questionnaire sent to radiologists affiliated with the Brazilian College of Radiology and Diagnostic Imaging. The questions were related to the demographic profile and professional practice characteristics (form of remuneration, primary imaging method employed, and subspecialty) of the radiologists, as well as their individual productivity (average personal productivity) and the productivity considered reasonable in a 6-h shift. The association between productivity and the practice characteristics of the radiologists was determined by using Poisson regression to calculate the prevalence ratio. RESULTS: A total of 510 radiologists completed the questionnaire. The great majority of the respondents (84%) reported that their remuneration is directly related to their productivity. The productivity varied according to the subspecialty, work environment, and remuneration model. CONCLUSION: We demonstrated that the productivity of radiologists is associated with the characteristics of their employment. We hope that this study will encourage other studies aimed at evaluating the productive capacity of the radiologists in Brazil, addressing the various functions they perform in their daily routine, including activities other than issuing reports.

Keywords: Radiologists/standards; Efficiency; Remuneration; Reimbursement, incentive; Workload; Diagnostic imaging/statistics & numerical data.