Measurement of kidney perfusion by magnetic resonance imaging: comparison of MRI with arterial spin labeling to para-aminohippuric acid plasma clearance in male subjects with metabolic syndrome.

BACKGROUND: Magnetic resonance imaging with arterial spin labeling (MRI-ASL) is a non-invasive approach to measure organ perfusion. We aimed to examine whether MRI-ASL kidney perfusion measurements are related to measurements of renal plasma flow (RPF) by para-aminohippuric acid (PAH) plasma clearance and whether changes of kidney perfusion in response to treatment with telmisartan can be detected by MRI-ASL. METHODS: Twenty-four patients with metabolic syndrome and an estimated creatinine clearance according to Cockroft and Gault of > or =60 ml/min were included in the study. Kidney perfusion was assessed by MRI-ASL measurements of a single coronal kidney slice (with flow-sensitive alternating inversion recovery and true fast imaging with steady-state processing sequence) and by measurements of RPF using PAH plasma clearance before and after 2 weeks of treatment with the angiotensin receptor blocker telmisartan. All MRI-ASL examinations were performed on a 1.5 T scanner. RESULTS: Two weeks of therapy with telmisartan led to a significant increase of RPF (from 313 +/- 47 to 348 +/- 69 ml/min/m, P = 0.007) and MRI-ASL kidney perfusion measurements (from 253 +/- 20 to 268 +/- 25 ml/min/100 g, P = 0.020). RPF measurements were related with MRI-ASL kidney perfusion measurements (r = 0.575, P < 0.001). Changes of RPF measurements and changes of MRI-ASL kidney perfusion measurements in response to treatment with telmisartan revealed a close relationship when expressed in absolute terms (r = 0.548, P = 0.015) and in percentage changes (r = 0.514, P = 0.025). CONCLUSIONS: Perfusion measurement of a single coronal kidney slice by MRI-ASL is able to approximate kidney perfusion and to approximate changes in kidney perfusion due to pharmacological intervention.

Nephrotoxicity of iso-osmolar iodixanol compared with nonionic low-osmolar contrast media: meta-analysis of randomized controlled trials.

PURPOSE: To compare the nephrotoxicity of iso-osmolar iodixanol with that of nonionic low-osmolar contrast media (CM) (LOCM) in randomized clinical trials. MATERIALS AND METHODS: This meta-analysis was conducted with a systematic search of MEDLINE, EMBASE, BIOSIS, Web of Science, ISI Web of Knowledge, Current Contents Medizin, Cochrane Library (until August 2007), trial registers, conference proceedings, and reference lists to identify studies and with requests from all manufacturers of CM for unidentified studies. Randomized controlled trials assessing serum creatinine levels before and after intravascular application of iodixanol or LOCM were included. The primary outcome measures were the incidence of contrast medium-induced nephropathy (CIN) and change in serum creatinine levels. RESULTS: Twenty-five trials were included. Iodixanol did not significantly reduce the risk of CIN (relative risk [RR], 0.80; 95% confidence interval [CI]: 0.61, 1.04; weighted mean difference in serum creatinine increase, 0.01 mg/dL [0.88 mumol/L]; 95% CI: -0.01, 0.03). There was no significant risk reduction after intravenous administration of the CM (RR, 1.08; 95% CI: 0.62, 1.89); subgroup with preexisting renal insufficiency (RR, 1.07; 95% CI: 0.56, 2.02) or after intraarterial administration (RR, 0.68; 95% CI: 0.46, 1.01); subgroup with preexisting renal insufficiency (RR, 0.59; 95% CI: 0.33, 1.07). However, in patients with intraarterial administration and renal insufficiency, the risk of CIN was greater for iohexol than for iodixanol (RR, 0.38; 95% CI: 0.21, 0.68), whereas there was no difference between iodixanol and the other (noniohexol) LOCM (RR, 0.95; 95% CI: 0.50, 1.78). CONCLUSION: Iodixanol is not associated with a significantly reduced risk of CIN compared with the LOCM pooled together. However, in patients with intraarterial administration and renal insufficiency, iodixanol is associated with a reduced risk of CIN compared with iohexol, whereas no significant difference between iodixanol and other LOCM could be found.

Impact of 131I SPECT/spiral CT on nodal staging of differentiated thyroid carcinoma at the first radioablation.

UNLABELLED: The purpose of this study was to determine the diagnostic value of 131I SPECT/spiral CT (SPECT/CT) on nodal staging of patients with thyroid carcinoma at the first ablative radioiodine therapy. METHODS: Fifty-seven patients were studied using SPECT/CT 3-4 d after receiving 3.96+/-0.5 GBq of 131I for radioablation of thyroid remnants after a thyroidectomy for differentiated thyroid carcinoma. In addition to planar whole-body scintigraphy, SPECT/CT of the neck was performed using a hybrid camera combining a double-head SPECT camera with either a 2-slice (n=23) or a 6-slice (n=34) spiral CT scanner. The planar scans and the SPECT/CT images were evaluated for cervical tracer uptake independently of each other and of the clinical findings. RESULTS: SPECT/CT led to a revision of the original diagnosis in 28 of 143 cervical foci of radioiodine uptake seen on planar imaging. In particular, SPECT/CT reclassified as benign 6 of 11 lesions considered to be lymph node metastases and 11 of 15 lesions considered to be indeterminate. Furthermore, SPECT/CT allowed the identification of 11 lymph node metastases classified as thyroid remnant or as indeterminate on planar imaging. Based on this revision, SPECT/CT yielded a gain in information on nodal stage in 20 of the 57 patients studied (35%, P<0.03). SPECT/CT altered nodal stage from N0 to N1 in 2 of 20 patients and from indeterminate (Nx) to N1 in 6 of 30 patients. The result was a change in risk stratification conforming to the classification proposed by the International Union Against Cancer in 14 patients (25%). CONCLUSION: SPECT/CT determines lymph node involvement at radioablation performed for thyroid cancer more accurately than does planar imaging. SPECT/CT may alter management in roughly one quarter of patients with thyroid carcinoma by upstaging or downstaging their disease.

Resectability of pancreatic adenocarcinoma: assessment using multidetector-row computed tomography with multiplanar reformations.

The purpose was to assess capabilities of the multidetector-row computed tomography (MDCT) with multiplanar reformations (MPR) for predicting of pancreatic adenocarcinoma resectability. Forty-eight patients deemed to have resectable pancreatic adenocarcinoma after assessment using biphasic MDCT with MPRs underwent surgery for potential tumor resection. Imaging findings were retrospectively evaluated for tumor resectability and correlated with surgical and pathological results. Curative resection was successful in 44 of 48 patients. The positive predictive value for tumor resectability made up 91% with four false-negative results. The reasons for unresectability were venous involvement (1), small liver metastases (2) and peritoneal involvement associated with small metastases to lymph nodes (1). MDCT yielded a negative predictive value of 99% (286 of 288 vessels) for detection of vascular invasion. Our results indicate the tendency towards improved prediction of resectability using MDCT compared to single-detector CT.

Direct MR galactography: feasibility study.

PURPOSE: To compare T1- and T2-weighted direct magnetic resonance (MR) galactography, indirect MR galactography, and conventional galactography in women with pathologic nipple discharge. MATERIALS AND METHODS: The study was approved by the institutional review board. Written informed consent was obtained from all patients. Twenty-three women (age range, 30-85 years) with pathologic nipple discharge and pathologic conventional galactographic findings underwent physical examination, ultrasonography, and MR imaging before surgery. A T2-weighted sequence of the affected breast was performed before (indirect MR galactography), and T1- and T2-weighted sequences were performed after (direct MR galactography), gadopentetate dimeglumine was injected into the discharging duct. MR galactographic findings were analyzed and compared with conventional galactographic findings. Sequences used were T2-weighted three-dimensional constructive interference in steady state (CISS), T1-weighted volumetric interpolated breath-hold examination (VIBE), and T1-weighted fast low-angle shot (FLASH). RESULTS: The 23 patients had a total of 57 findings at conventional galactography. Indirect MR galactography with CISS showed pathologic findings in eight (42%) of 19 patients and showed 15 (33%) of 46 of all findings. Direct MR galactography with CISS showed pathologic findings in 23 (100%) of 23 patients and 47 (82%) of 57 of all findings, that with VIBE showed pathologic findings in 19 (83%) of 23 patients and 38 (67%) of 57 of all findings, and that with FLASH showed pathologic findings in 16 (100%) of 16 patients and 31 (80%) of 39 of all findings. There was a significant (P < .01) difference between indirect MR galactography and all direct MR galactography sequences in the detection of ductal disease. Eight (35%) of 23 women showed additional findings at direct MR galactography in comparison with standard MR imaging sequences. CONCLUSION: MR galactography has the potential to be used in the diagnostic work-up of pathologic nipple discharge. Direct MR galactography shows more disease than does indirect MR galactography. The highest detection rate for ductal disease compared with that at conventional galactography was found with the direct MR galactography CISS and FLASH sequences.

Right heart: split-bolus injection of diluted contrast medium for visualization at coronary CT angiography.

PURPOSE: To retrospectively compare a split-bolus contrast medium injection protocol with a biphasic and a monophasic protocol in terms of visualization of the right and left heart, contrast medium-related streak artifacts, and level of attenuation in the cardiac chambers and coronary arteries at coronary computed tomographic (CT) angiography. MATERIALS AND METHODS: The human research committee approved this HIPAA-compliant study and waived informed consent. Seventy-five patients had undergone 64-section coronary CT angiography: 25 were injected by using a monophasic, contrast-medium-only protocol with a single-syringe injector; 25 were injected by using a biphasic protocol with a dual-syringe injector; and 25 were injected by using a split-bolus protocol with a dual-syringe injector and an initial bolus of contrast medium followed by 50 mL of a 70%:30% saline-to-contrast medium mixture and a 30-mL saline chaser. Two radiologists rated the visualization of right and left heart structures and the degree of streak artifacts. One observer performed attenuation measurements of the cardiac chambers and of the coronary arteries. Data were analyzed with one-way analysis of variance and Duncan post-hoc multiple comparison procedures. RESULTS: Data for 27 women and 48 men (mean age, 62 years) were included. Mean contrast medium attenuation in the right heart was significantly (P < .001) higher in the split-bolus group than in the biphasic injection group but was significantly (P < .001) lower than in the monophasic injection group. For the left heart and the coronary arteries, there were no significant differences among the three groups. Artifacts occurred less frequently (P < .001) in the biphasic and split-bolus groups than in the monophasic group. Visualization of right heart structures was rated significantly (P < .05) better in the split-bolus group than in the two other groups, while there was no difference for visualization of left heart structures. CONCLUSION: Split-bolus injection provides sufficient attenuation for visualization of the right heart, while streak artifacts from high-attenuation contrast material can generally be avoided and arterial attenuation is maintained.

Thin-slice MDCT of the neck: impact on cancer staging.

OBJECTIVE: The objective of this study was to compare thin-slice multiplanar evaluation and conventional 3-mm axial evaluation of head and neck MDCT in tumor staging. MATERIALS AND METHODS: Ninety-six patients with histologically proven squamous cell carcinoma were evaluated independently, once using 3-mm axial images and once using 1-mm interactive multiplanar reformation (MPR) images. Tumor stage was assessed with both methods; histology served as the reference. Thirty-seven patients with hypopharyngeal and laryngeal tumors had en bloc resection, allowing direct comparison of tumor infiltration into designated anatomic structures. Two examiners independently assessed the data sets. Interobserver agreement was tested with a modified kappa test. The Wilcoxon signed rank test with continuity correction was applied to test the null hypothesis, which postulates the equality of both methods. The chi-square test was applied to compare the number of correctly classified tumors for the two methods and readers. RESULTS: Interobserver agreement was high (kappa = 0.88-0.91). Both methods allowed accurate tumor staging, and no significant differences between the two methods were found (reader A, p = 0.61; reader B, p = 1). With MPR assessment, more anatomic structures were rated positive for tumor infiltration, but diagnostic accuracy did not differ significantly in the subgroup of patients with histologic correlation from en bloc resection. CONCLUSION: Conventional 3-mm axial evaluation of head and neck MDCT proved to be sufficient in tumor staging.

Contrast-enhanced T1-weighted fluid-attenuated inversion-recovery BLADE magnetic resonance imaging of the brain: an alternative to spin-echo technique for detection of brain lesions in the unsedated pediatric patient?

RATIONALE AND OBJECTIVES: We compared contrast-enhanced T1-weighted magnetic resonance (MR) imaging of the brain using different types of data acquisition techniques: periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER, BLADE) imaging versus standard k-space sampling (conventional spin-echo pulse sequence) in the unsedated pediatric patient with focus on artifact reduction, overall image quality, and lesion detectability. MATERIALS AND METHODS: Forty-eight pediatric patients (aged 3 months to 18 years) were scanned with a clinical 1.5-T whole body MR scanner. Cross-sectional contrast-enhanced T1-weighted spin-echo sequence was compared to a T1-weighted dark-fluid fluid-attenuated inversion-recovery (FLAIR) BLADE sequence for qualitative and quantitative criteria (image artifacts, image quality, lesion detectability) by two experienced radiologists. Imaging protocols were matched for imaging parameters. Reader agreement was assessed using the exact Bowker test. RESULTS: BLADE images showed significantly less pulsation and motion artifacts than the standard T1-weighted spin-echo sequence scan. BLADE images showed statistically significant lower signal-to-noise ratio but higher contrast-to-noise ratios with superior gray-white matter contrast. All lesions were demonstrated on FLAIR BLADE imaging, and one false-positive lesion was visible in spin-echo sequence images. CONCLUSION: BLADE MR imaging at 1.5 T is applicable for central nervous system imaging of the unsedated pediatric patient, reduces motion and pulsation artifacts, and minimizes the need for sedation or general anesthesia without loss of relevant diagnostic information.

[Suggestions for prevention of adverse reactions after intravasal administration of iodinated contrast media]. / Empfehlungen zur Prophylaxe der Nebenwirkungen bei intravasaler Applikation jodhaltiger Kontrastmittel. Suggestions for prevention of adverse reactions after intravasal administration of iodinated contrast media.

Iodinated contrast media are widely used in computed tomography and angiography. Adverse reactions such as contrast-medium induced nephropathy (CIN), anaphylactoid reactions and iodine-induced thyrotoxicosis are associated with intravasal administration of contrast agents. Iodinated contrast agents are generally considered to be safe, but in rare cases they can cause severe life threatening situations. In this review we present an overview about the incidence, pathways, and risk factors of adverse reactions. Simple schemes including hydration protocols for prevention of CIN, medication for prophylaxis of iodine-induced thyrotoxicosis with thyreostatics and anaphylactoid reactions with histamine antagonists and corticosteroids are suggested.

[Diagnosis of fungal pneumonia in the thoracic CT]. / Diagnose der Pilzpneumonie in der Thorax-CT CT scan findings of fungal pneumonia.

The importance of fungal infection of the lung in immunocompromised patients has increased substantially during the last decades. Numerically the most patients are those with neutropenia, e.g., patients with malignancies or solid organ and stem cell transplantation, chemotherapy, corticosteroid use and HIV infection. Although fungal infections can occur in immunocompetent patients, their frequency in this population is rare. The clinical symptoms such as fever accompanied with non-productive cough are unspecific. In some patients progression to hypoxemia and dyspnea may occur rapidly. In spite of improved antifungal therapy morbidity and mortality of these infections are still high. Therefore an early and non-invasive diagnosis is very important. That is why CT and even better High-Resolution-CT (HR-CT) is a very important modality in examining immunocompromised patients with a probability of fungal infection. CT is everywhere available and, as a non-invasive method, able to give the relevant diagnose efficiently. This paper should give an overview about the radiologic findings and possible differential diagnosis of diverse pulmonary fungal infections in CT. Pneumonias caused by Aspergillus, Cryptococcus, Candida, Histoplasma, Mucor and Geotrichum capitatum are illustrated.

[Differential diagnosis of focal lesions of the kidney in CT and MRT]. / Differentialdiagnose fokaler Nierenläsionen in CT und MRT.

The great majority of renal masses are found incidentally as a result of the use of ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI). If ultrasonography is not diagnostic CT or MRI should be initiated to differentiate lesions of the kidney that need surgical intervention from those that do not and from those that need follow-up examinations. Cystic renal masses are characterized by using the Bosniak classification, including category IIF. In solid Lesions of the kidney first non-surgical lesions as well as lymphoma, renal infarction and nephritis should be excluded. Identifying fatty components in renal lesions is very important because in angiomyolipoma they are almost always present. CT and MRI are exellent for tumor detection. Careful evaluation of imaging finding combined with the patient's history should assist the radiologist in making the proper diagnosis or recommending the appropriate treatment in most cases. This article provides a review about renal masses, the imaging methods for their evaluation and their characteristic features at CT and MR imaging. Different lesions are demonstrated like xantogranulomatous pyelonephritis, acute pyelonephritis, renal infarction, lymphoma, angiomyolipoma, renal oncocytoma, cystic lesion and polycystic disease the kidney, echinococcosis, renal cystadenoma, metastases, renal cell carcinoma (RCC), and multiple bilateral RCC in patients with Hippel-Lindau-Syndrome. This article should help to differentiate complex cystic lesions of the kidney by using the Bosniak-classification, especially Bosniak Category IIF. Solid masses should be characterized and the major question to be answered is whether the mass represents a surgical or nonsurgical lesion or if follow-up studies are necessary.

[The von Meyenburg complex]. / Der von Meyenburg Komplex.

The von Meyenburg complex (VMC) describes bile duct hamartomas and presents a rare, benign incidental finding in liver imaging. We report on a 61-year-old man, who was referred for a follow up study 14 years after remission of Hodgkin's disease. Computed tomography (CT) revealed multiple hypodense lesions throughout the liver, primary suggesting recurrent Hodgkin's disease. Previous CT-examinations, which were obtained at a later date, showed those Lesions in identical distribution and morphology over the years, leading to diagnosis of multiple bile duct hamartomas (VMC). Making imaging-based diagnosis of VMC including ultrasound, CT and magnetic resonance imaging is a challenging task for the radiologist. Based on literature research findings, the impact of different modalities in the diagnostic work-up of VMC is discussed.

[Hypoxic injury of all deep nuclei of the brain--a case report from computed tomography]. / Hypoxischer Schaden aller tiefen Kerngebiete des Gehirns--ein Fallbericht aus der Computertomographie.

Though being inferior to magnetic resonance imaging, computed tomography (CT) of the brain is the most frequently applied imaging modality in the diagnostic workup of acute cerebral Ischaemia. We report on a case of a comatose 53-year-old man who was brought to the emergency room after cardiopulmonary resuscitation. The CT of the brain showed a diffuse brain oedema with an explicit hypodense demarcation of all deep nuclei.

Extraosseous manifestation of multiple myeloma with unusual appearance in computed tomography--case report.

Extramedullary Localizations at diagnosis or during the course of multiple myeloma are rare. We report on a 70 year old patient, presenting multiple hypoechoic liver lesions during an ultrasound examination. The following contrast-enhanced computed tomography demonstrated hypodense liver Lesions with slight contrast enhancement and hyperdense polypoid masses in the wall of the gall bladder as well as a small pericostal tumor. A punch biopsy of the liver and immunohistochemical studies confirmed the diagnosis of extramedullary multiple myeloma. In a follow-up CT five weeks later the liver lesions and the pericostal tumor clearly showed progress, the masses in the gall bladder had developed into a concentric wall-thickening. Additionally, polypoid contrast-enhancing masses in the gastric wall became apparent as well as a hypodense lesion in the spleen. Radiologists should be aware that multiple myeloma can on rare occasions present as hypodense nodules in the liver or new masses in other organs in CT. Because of the morphologic similarity to metastatic disease, a biopsy may be necessary for definitive diagnosis.

Diagnostic accuracy of noninvasive coronary angiography in patients after bypass surgery using 64-slice spiral computed tomography with 330-ms gantry rotation.

BACKGROUND: Multidetector computed tomographic angiography (MDCT) has been shown to allow detection of coronary artery bypass graft (CABG) occlusions and stenoses. However, the assessment of native coronary arteries in addition to CABG has thus far not been sufficiently validated. METHODS AND RESULTS: Fifty patients with a total of 138 CABG (34 mammary grafts, 3 radial grafts, 101 venous grafts) were investigated by MDCT (0.6-mm collimation, 32 detector rows, 2 focal points, 330-ms rotation) 9 to 252 months (mean, 106 months) after surgery. CABG and all native coronary arteries with a diameter of > 1.5 mm were evaluated for the presence of significant stenoses (> or = 50% diameter reduction). Results were compared with quantitative coronary angiography. By MDCT, all CABG were evaluable and were correctly classified as occluded (n=38) or patent (n=100). Sensitivity for stenosis detection in patent grafts was 100% (16/16) with a specificity of 94% (79/84). For the per-segment evaluation of native coronary arteries and distal runoff vessels, sensitivity in evaluable segments (91%) was 86% (87/101) with a specificity of 76% (354/465). If evaluation was restricted to nongrafted arteries and distal runoff vessels, sensitivity was 86% (38/44) with a specificity of 90% (302/334). On a per-patient basis, classifying patients with at least 1 detected stenosis in a CABG, a distal runoff vessel, or a nongrafted artery or with at least 1 unevaluable segment as "positive," MDCT yielded a sensitivity of 97% (35/36) and specificity of 86% (12/14). CONCLUSIONS: We found that 64-slice MDCT permits the evaluation of bypass grafts and the assessment of the native coronary arteries for the presence of stenosis.

Reversibility and time-dependency of contrast medium induced inhibition of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) conversion in renal proximal tubular cells in vitro: comparison of a monomeric and a dimeric nonionic iodinated contrast medium.

OBJECTIVES: To evaluate the time-course and reversibility of toxicity of a low-osmolar and an iso-osmolar radiographic contrast medium on renal tubular cell cultures. MATERIALS AND METHODS: LLC-PK1-cells were incubated with iomeprol, iodixanol, and mannitol (4.7-75 mg I/mL, 2-24 hours). Metabolic activity was assessed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide-(MTT) assay. RESULTS: Iomeprol and iodixanol induced a time- and dose-dependent inhibition of MTT conversion (75%-19% and 70%-23% of control for iomeprol and iodixanol, respectively, at concentrations ranging from 4.7 to 75 mg I/mL after an incubation time of 2 hours and 64%-14% and 65%-12% of control after 24 hours). The mannitol induced inhibition of the MTT conversion was significantly weaker than that induced by iomeprol (99%-47% of control at concentrations corresponding to 4.7-75 mg I/mL after an incubation time of 24 hours, P < 0.001). After 24 hours incubation with iomeprol, iodixanol, or mannitol and a recovery time of 2 hours after removal of the test-solutions, there was only a small inhibition of MTT-conversion (89%, 88%, and 95% of control at 75 mg I/mL). CONCLUSIONS: Contrast medium induced cytotoxicity consisted of a reversible part and an irreversible part. There was no difference in cytotoxicity between iomeprol and iodixanol over a broad range of concentrations and incubation-times.

Diffusion weighted imaging in breast MRI: comparison of two different pulse sequences.

RATIONALE AND OBJECTIVES: Comparison of two different diffusion weighted (DW) sequences in breast MRI regarding the differentiation between benign and malignant lesions. MATERIALS AND METHODS: Breast MRI including two different DW sequences was performed in 165 consecutive women. Inclusion criteria for DW imaging and ADC evaluation were histologically proven focal mass lesions with a diameter of more than 5 mm in dynamic contrast-enhanced MRI. The DW sequences were pre-contrast echo-planar imaging with spectral fat saturation (EPI fs) and DW EPI with inversion recovery (EPI STIR) (b-values: 50, 400, and 800). Lesions were analyzed regarding visibility in DW sequences and ADC values. RESULTS: Inclusion criteria were fulfilled in 56 women with 69 lesions. Five lesions could not be evaluated for different reasons. Finally, DW sequences were evaluated in 51 women with 64 focal mass lesions (15 benign, 49 malignant). The visibility of the lesions was significantly better in the EPI fs sequence (P<0.05). The ADC values (10(-3) mm(2)/s) in the EPI fs were 1.76, 2.58, and 1.21 (mean, maximum, minimum, respectively) for benign lesions and 0.90, 1.19, and 0.34 for malignant lesions. Respective values in the EPI STIR sequence were 1.92, 3.20, 1.10, and 0.91, 1.43, 0.35. Only in the EPI fs sequence there was no overlap in ADC values between benign and malignant lesions. CONCLUSION: The DW MRI of the breast with EPI fs and EPI STIR sequences has a high potential to differentiate between benign and malignant breast lesions. Due to better lesion visibility and selectivity, the EPI fs sequence should be preferred.

Modes of information delivery in radiologic anatomy education: Impact on student performance.

RATIONALE AND OBJECTIVES: This study provides a systematic assessment of different methods of delivering radiologic teaching content (lecture, printed text, and digital content delivery) under standard conditions, enabling comparison of the effectiveness of these methods. MATERIALS AND METHODS: A printed atlas of sectional anatomy was used as a standard. Digital content was developed on the basis of the printed atlas. Lecturers used both the printed and the digital content to prepare lectures. Standardized teaching material thus created was presented to second-term undergraduate students who had attended the school's anatomy course, but had not received any radiology teaching. Multiple choice examinations were used to assess the students' ability to recognize anatomical structures in known as well as unknown images. In a survey, the students' subjective experience of the learning process was assessed. RESULTS: No difference was seen between the groups regarding examination results. Students preferred a combination of digital media and lectures by enthusiastic teachers. CONCLUSIONS: The shortage of teachers requires a compromise concerning the delivery of radiologic anatomy content in a medical school setting. Based on our results, we recommend a combined approach of lecture and digital content delivery.

The value of dynamic MRI studies in parotid tumors.

RATIONALE AND OBJECTIVES: To evaluate the ability of dynamic contrast-enhanced magnetic resonance imaging (MRI) to differentiate several tumor entities of the parotid gland in a prospective clinical trial. MATERIALS AND METHODS: A total of 112 patients with parotid tumors were examined with dynamic contrast-enhanced 1.5 T MRI. Precontrast axial T1-weighted imaging was used to select five slices for the dynamic study. Subsequently, a T1-weighted FLASH sequence was used for the dynamic contrast study (0.2 ml Gd/kg x body weight). Contrast agent application and the FLASH sequence were started simultaneously. Ten acquisitions of 10 seconds' scan time each were performed (total acquisition time 1:40 minutes). Signal intensity versus time (SIvT) curves was obtained for all tumors. After correlation of the categorized SIvT curves, these were compared with histopathology. Finally, all MRIs together with the tumor specific SIvT curves were re-read and correlated with histopathologic diagnosis. All reading sessions were done by three experienced radiologists. RESULTS: Four characteristic intensity-time curves were observed: pleomorphic adenoma showed a gradual increase in signal intensity, followed by a plateau phase on a low intensity level. Cysts showed a vacillating course at a low signal intensity level. Adenolymphomas as well as carcinomas showed a rapid increase in signal intensity followed by a plateau phase. Statistic significance was found for the time-to-peak values for adenolymphomas and pleomorphic adenomas and for the maximum peak signal intensity values for carcinomas. Together with other morphologic MRI criteria (contrast enhancement, border characteristics) and clinical features, a differentiation between adenolymphoma and carcinoma was possible. CONCLUSIONS: With additional dynamic contrast-enhanced MRI, a more reliable differentiation between common parotid tumors is possible before surgery.

Contrast enhanced sonography of the gallbladder: a tool in the diagnosis of cholecystitis?

RATIONALE AND OBJECTIVES: To evaluate if contrast enhanced sonography (CES) can help to detect gallbladder inflammation and differentiate between acute and chronic cholecystitis. MATERIALS AND METHODS: Thirty-three patients with clinical suspicion of acute cholecystitis were examined with CES before cholecystectomy. Thirty patients with no history of gallbladder disease served as control. CES was performed using 2.5 mL SonoVue. A small mechanical index was chosen (0.1). The enhancement pattern of the gallbladder was ranked in a three-point scale: no enhancement, low enhancement and strong enhancement. 28/33 patients underwent surgery. Sonographic findings were compared to histological results. RESULTS: In 16/20 cases with histological proven acute cholecystitis, the gallbladder wall showed a strong enhancement. Low enhancement was found in four patients with acute and in six patients with chronic cholecystitis. The gallbladder wall of two patients with chronic inflammation and all patients (30/30) of the control group showed no enhancement. CONCLUSION: CES is a feasible tool for detecting gallbladder inflammation. Differentiating between acute and chronic cholecystitis seems to be possible.