Till R. Bader

Timing of the hepatic arterial phase during contrast-enhanced computed tomography of the liver: assessment of normal values in 25 volunteers.

OBJECTIVES To define normal values of the beginning and duration of the hepatic arterial phase (HAP) during contrast-enhanced computed tomography (CT). METHODS Twenty-five volunteers (16 men, 9 women; mean age, 60.0 years) without history or suspicion of liver disease were examined with dynamic single-section CT. Scanning was performed at a single level that included the liver, aorta, and portal vein. A series of 25 scans was obtained over a period of 88 seconds (1 baseline scan followed by 16 scans every 2 seconds and 8 scans every 7 seconds) beginning with the injection of a bolus of contrast agent (40 mL, 10 mL/s) and a 40-mL NaCl bolus chaser. Contrast enhancement in the liver, aorta, and portal vein was measured with regions of interest, and time-density curves were obtained. These data were processed with a pharmacodynamic fitting program and the duration of the HAP was calculated. The onsets of the HAP and the portal venous phase were assessed as lag times, referring to the beginning of enhancement in the abdominal aorta. RESULTS The mean lag time of the HAP was 5.4 seconds after the aorta and the mean duration was 8.6 seconds. The mean lag time of the portal venous phase was 13.9 seconds after the aorta. CONCLUSIONS These data can be used to optimize protocols for routine CT. Because of the short duration of the HAP, imaging of the entire liver during this phase is possible only with multidetector CT scanners.

Measurement of hepatic perfusion with dynamic computed tomography: assessment of normal values and comparison of two methods to compensate for motion artifacts.

Bader TR, Grabenwöger F, Prokesch RW, Krause W. Measurement of hepatic perfusion with dynamic computed tomography: Assessment of normal values and comparison of two methods to compensate for motion artifacts. Invest Radiol 2000;35:539–547. RATIONALE AND OBJECTIVES.To assess normal values of hepatic perfusion by dynamic, single-section computed tomography, to compare two methods of data processing (a smoothing with a fitting procedure), and to evaluate the influence of motion artifacts. METHODS.Twenty-five volunteers with no history or suspicion of liver disease were examined (age range, 32.8–81.1 years). All examinations were subjectively ranked into groups 1 through 3 according to the degree of motion artifacts (negligible, moderate, severe). All data were processed with a smoothing procedure and a pharmacokinetic fitting procedure (TopFit). The arterial, portal venous, and total hepatic perfusion; the hepatic perfusion index (HPI); and the arterial/portal venous ratio (A/P ratio) were calculated with both procedures. RESULTS.Mean hepatic perfusion, as assessed with the fitting procedure and the smoothing procedure, respectively, was as follows: arterial, 0.20 and 0.22 mL·min−1·mL−1; portal venous, 1.02 and 1.24 mL·min−1·mL−1; total perfusion, 1.22 and 1.47 mL·min−1·mL−1; HPI, 16.4% and 15.4%; and A/P ratio, 0.20 and 0.19. The differences were significant for the portal venous and total hepatic perfusion. The portal venous and total hepatic perfusion values showed significant differences between group 1 and groups 2 and 3 for both procedures. HPI and the A/P ratio showed no significant differences at all. CONCLUSIONS.Motion artifacts and the type of data processing influence the assessment of the arterial, portal venous, and total hepatic perfusion but do not influence measurement of the HPI and the A/P ratio.

Role of Doppler Sonography in the Evaluation of Accessory Spleens After Splenectomy

Splenectomy influences the Doppler blood flow pattern in the splenic artery. Blood flow in this vessel might return to normal if an accessory spleen increases in size after splenectomy. Our objective was to evaluate the resistive index of the splenic artery depending on the presence or absence of a hypertrophic accessory spleen in splenectomized patients.

Displacement of coils into the lung during embolotherapy: clinical importance and follow-up with helical CT.

RATIONALE AND OBJECTIVES The authors performed this study to evaluate the clinical importance and computed tomographic (CT) appearance of coils displaced into the lung during embolotherapy. MATERIALS AND METHODS The authors retrospectively studied clinical charts and serial chest images from 25 consecutive patients after coil embolization. Chest radiography was performed in all patients, whereas helical chest CT was performed only in patients in whom dislocated coils were visible on chest radiographs. Coils were applied for the treatment of peripheral arteriovenous (AV) malformations and fistulas (n = 9), renal AV malformations or fistulas (n = 8), and primary or secondary tumors (n = 8). Clinical charts were analyzed for short- and long-term symptoms; chest radiographs and CT scans were reviewed for signs indicative of pulmonary infarction. RESULTS None of the patients had clinical symptoms suggestive of pulmonary infarction. In two of the 25 patients (8%), displaced coils were seen in the pulmonary vasculature at chest radiography; these patients had been treated for renal AV fistula and peripheral AV fistula, respectively. One patient had two coils in the left hemithorax (upper and lower lobe), and the other patient had two coils in the right hemithorax (middle lobe). Neither of the patients had abnormalities suggestive of pulmonary infarction at helical CT. CONCLUSION Chest radiography can help confirm the presence of coils displaced to the pulmonary vasculature during embolotherapy. Helical CT can also help rule out the presence of coil-associated pulmonary infarction.

Health care reform in the USA: Recommendations from USA and non-USA radiologists

AIM To compare the opinions and recommendations of imaging specialists from United States (USA) and non-USA developed nations for USA health care reform. METHODS A survey was emailed out to 18 imaging specialists from 17 non-USA developed nation countries and 14 radiologists within the USA regarding health care reform. The questionnaire contained the following questions: what are the strengths of your health care system, what problems are present in your nations health care system, and what recommendations do you have for health care reform in the USA. USA and non-USA radiologists received the same questionnaire. RESULTS Strengths of the USA health care system include high quality care, autonomy, and access to timely care. Twelve of 14 (86%) USA radiologists identified medicolegal action as a major problem in their health care system and felt that medicolegal reform was a critical aspect of health care reform. None of the non-USA radiologists identified medicolegal aspects as a problem in their own country nor identified it as a subject for USA health care reform. Eleven of 14 (79%) USA radiologists and 16/18 (89%) non-USA radiologists identified universal health care coverage as an important recommendation for reform. CONCLUSION Without full universal coverage, meaningful health care reform will likely require medicolegal reform as an early and important aspect of improved and efficient health care.