Imaging techniques for assessment of inflammatory bowel disease: joint ECCO and ESGAR evidence-based consensus guidelines.

The management of patients with IBD requires evaluation with objective tools, both at the time of diagnosis and throughout the course of the disease, to determine the location, extension, activity and severity of inflammatory lesions, as well as, the potential existence of complications. Whereas endoscopy is a well-established and uniformly performed diagnostic examination, the implementation of radiologic techniques for assessment of IBD is still heterogeneous; variations in technical aspects and the degrees of experience and preferences exist across countries in Europe. ECCO and ESGAR scientific societies jointly elaborated a consensus to establish standards for imaging in IBD using magnetic resonance imaging, computed tomography, ultrasonography, and including also other radiologic procedures such as conventional radiology or nuclear medicine examinations for different clinical situations that include general principles, upper GI tract, colon and rectum, perineum, liver and biliary tract, emergency situation, and the postoperative setting. The statements and general recommendations of this consensus are based on the highest level of evidence available, but significant gaps remain in certain areas such as the comparison of diagnostic accuracy between different techniques, the value for therapeutic monitoring, and the prognostic implications of particular findings.

Unenhanced versus multiphase MDCT in patients with hematuria, flank pain, and a negative ultrasound.

OBJECTIVES: To compare the impact of unenhanced and contrast-enhanced multi-detector computed tomography (MDCT) for the detection of urinary stones and urinary obstruction in patients with suspected renal colic. METHODS: 95 patients with suspected renal colic underwent a three-phase MDCT for evaluation of the urinary tract. The unenhanced scan and the multiphase examination were reviewed retrospectively by two radiologists for the characterization of urinary stones and signs of obstruction. Results of unenhanced MDCT were compared with those obtained during the second review of the entire multiphase examination. RESULTS: Overall diagnosis of urinary stones revealed an accuracy of 97.0% for unenhanced, and 98.9% for multiphase MDCT with a significant difference between both protocols (mixed-effects logistic regression: odds ratio 3.3; p=0.019). With 3 versus 15 false positive ratings, multiphase MDCT was superior to unenhanced MDCT for the diagnosis of urinary stones. There was no significant difference in detecting signs of obstruction. Inter-reader agreement for overall stone detection was excellent on both unenhanced (kappa 0.84) and multiphase (kappa 0.88) MDCT. CONCLUSION: Contrast-enhanced multiphase MDCT offers distinct advantages compared to an unenhanced approach for the assessment of urinary stone disease, and therefore should be considered as a complementary examination for patients with inconclusive findings.

MR defecography in patients with dyssynergic defecation: spectrum of imaging findings and diagnostic value.

OBJECTIVES: We describe the spectrum of findings and the diagnostic value of MR defecography in patients referred with suspicion of dyssynergic defecation. METHODS: 48 patients (34 females, 14 males; mean age 48 years) with constipation and clinically suspected dyssynergic defecation underwent MR defecography. Patients were divided into patients with dyssynergic defecation (n = 18) and constipated patients without dyssynergic defecation (control group, n = 30). MRIs were analysed for evacuation ability, time to initiate evacuation, time of evacuation, changes in the anorectal angle (ARA-change), presence of paradoxical sphincter contraction and presence of additional pelvic floor abnormalities. Sensitivity, specificity, positive and negative predictive values and accuracy for the diagnosis of dyssynergic defecation were calculated. RESULTS: The most frequent finding was impaired evacuation, which was seen in 100% of patients with dyssynergic defecation and in 83% of the control group, yielding a sensitivity for MR defecography for the diagnosis of dyssynergic defecation of 100% (95% confidence interval (CI) 97-100%), but a specificity of only 23% (95% CI 7-40%). A lower sensitivity (50%; 95% CI 24-76%) and a high specificity (97%; 95% CI 89-100%) were seen with abnormal ARA-change. The sensitivity of paradoxical sphincter contraction was relatively high (83%; 95% CI 63-100%). A combined analysis of abnormal ARA-change and paradoxical sphincter contraction allowed for the detection of 94% (95% CI 81-100%) of the patients with dyssynergic defecation. CONCLUSION: MR defecography detects functional and structural abnormal findings in patients with clinically suspected dyssynergic defecation. Impaired evacuation is seen in patients with functional constipation owing to other pelvic floor abnormalities than dyssynergic defecation.

18F-FDG-PET and MRI in patients with malignancies of the liver and pancreas. Accuracy of retrospective multimodality image registration by using the CT-component of PET/CT.

PURPOSE: To evaluate the accuracy of retrospective rigid image registration and fusion between F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) of the upper abdomen. PATIENTS, MATERIAL, METHODS: Image fusion of PET and MRI was performed in 30 patients with suspected malignancy of the liver or pancreas. Using a commercially available image fusion tool capable of rigid manual point-based registration, PET-Images were retrospectively registered and fused by matching eight homologous points in the 3D spoiled gradient echo (GRE) MRI sequences acquired in portal venous phase and in the CT-component of PET/CT. Two separate observers (R1, R2) assessed accuracy of image registration by determining the distances in the x-, y- and z-axis as well as the absolute distance between anatomical landmarks which differed from the landmarks chosen for registration. Quality of fusion was graded using a three point grading scale (1 poorly fused; 2 satisfactory fused; 3 correctly fused) and compared to hybrid PET/CT fusion. RESULTS: Mean time of registration per patient was less than 2 minutes. Objective registration assessment showed errors between 2.4-6.3 mm in x-axis: mean 3.6 mm (R1); 4.6 mm (R2), 2.3-9.3 mm in y-axis (mean 5.1 mm; 5.5 mm) and 3.3-12.0 mm in z-axis (mean 5.9 mm; 5.9 mm.) The mean error in absolute distance between points was 6.0-16.8 mm (mean 9.9 mm; 10.6 mm). In visual assessment, most fusions were graded to be satisfactory or correctly fused: R1, R2: grade 3, 11/30 (36.7%), 22/30 (73.3%); grade 2, 13/30 (43.3%), 8/30 (26.7%); grade 1, 6/30 (20%), 0/30 (0%). Fusions were mostly comparable to hybrid PET/CT fusions. All of the fusions were defined as diagnostically relevant by both observers. CONCLUSION: Retrospective rigid image fusion of FDG-PET and MRI of the upper abdomen using the CT-component of PET/CT for registration is feasible without adaptation in image acquisition protocols and shows sub-centimeter registration errors in most cases.

CT- and MRI-based volumetry of resected liver specimen: comparison to intraoperative volume and weight measurements and calculation of conversion factors.

OBJECTIVE: To compare virtual volume to intraoperative volume and weight measurements of resected liver specimen and calculate appropriate conversion factors to reach better correlation. METHODS: Preoperative (CT-group, n=30; MRI-group, n=30) and postoperative MRI (n=60) imaging was performed in 60 patients undergoing partial liver resection. Intraoperative volume and weight of the resected liver specimen was measured. Virtual volume measurements were performed by two readers (R1,R2) using dedicated software. Conversion factors were calculated. RESULTS: Mean intraoperative resection weight/volume: CT: 855 g/852 mL; MRI: 872 g/860 mL. Virtual resection volume: CT: 960 mL(R1), 982 mL(R2); MRI: 1112 mL(R1), 1115 mL(R2). Strong positive correlation for both readers between intraoperative and virtual measurements, mean of both readers: CT: R=0.88(volume), R=0.89(weight); MRI: R=0.95(volume), R=0.92(weight). Conversion factors: 0.85(CT), 0.78(MRI). CONCLUSION: CT- or MRI-based volumetry of resected liver specimen is accurate and recommended for preoperative planning. A conversion of the result is necessary to improve intraoperative and virtual measurement correlation. We found 0.85 for CT- and 0.78 for MRI-based volumetry the most appropriate conversion factors.

A simple method to approximate liver size on cross-sectional images using living liver models.

AIM: To assess whether a simple. diameter-based formula applicable to cross-sectional images can be used to calculate the total liver volume. MATERIALS AND METHODS: On 119 cross-sectional examinations (62 computed tomography and 57 magnetic resonance imaging) a simple, formula-based method to approximate the liver volume was evaluated. The total liver volume was approximated measuring the largest craniocaudal (cc), ventrodorsal (vd), and coronal (cor) diameters by two readers and implementing the equation: Vol(estimated)=cc x vd x cor x 0.31. Inter-rater reliability, agreement, and correlation between liver volume calculation and virtual liver volumetry were analysed. RESULTS: No significant disagreement between the two readers was found. The formula correlated significantly with the volumetric data (r>0.85, p<0.0001). In 81% of cases the error of the approximated volume was <10% and in 92% of cases <15% compared to the volumetric data. CONCLUSION: Total liver volume can be accurately estimated on cross-sectional images using a simple, diameter-based equation.

USPIO-enhanced magnetic resonance imaging of the knee in asymptomatic volunteers.

The aim of this study was to compare signal characteristics of the synovium in knees of asymptomatic volunteers before and after intravenous administration of ultrasmall superparamagnetic iron oxide particles (USPIO). Ten knees of 10 asymptomatic volunteers were examined before and 36 h after intravenous administration of USPIO on a 1.5-T MR system using T1-weighted spin-echo, T2-weighted fast spin-echo, T2*-weighted gradient-echo (GRE), and short inversion time inversion-recovery sequences. In addition, synovial perfusion was measured using Gd-enhanced GRE imaging during the first imaging session. Images were analyzed qualitatively for any visual changes before and after USPIO administration. Signal-to-noise ratios (SNR) of the synovium were determined on unenhanced and USPIO-enhanced sequences. All MR images were reviewed for presence of any degenerative changes. Qualitative image analysis revealed no visually detectable changes of any knee joint before and after USPIO administration. The SNR values of the synovium on T1w, T2w, and T2*w images before and after USPIO administration showed no significant difference (T1, P = 0.86; T2, P = 0.95; T2*, P = 0.86). None of the volunteers showed any relevant degenerative changes of the knee and synovial perfusion was within normal limits. In knees of asymptomatic volunteers without any relevant degenerative changes and normal synovial perfusion neither visual changes nor changes of SNR values of the synovium can be depicted after USPIO administration. This means that USPIO-enhanced MRI may be used for assessment of knee disorders with increased macrophage activity.

Impact of vessel attenuation on quantitative coronary angiography with 64-slice CT.

The aim of the study was to determine the impact of vessel attenuation on quantitative 64-slice computed tomography coronary angiography (CTCA). CTCA and invasive quantitative coronary angiography (QCA) were performed in 100 consecutive patients (42 women, 58 men; mean age 64.4+/-9.4 years; age range 39-87 years). In QCA, stenoses were quantified with dedicated software, whereas in CTCA, stenosis severity was assessed with an electronic caliper tool: stenoses were graded in 10% steps and assigned as either a calcified or non-calcified lesion. Vessel attenuation in the left main (LMA) and the proximal right coronary artery (RCA) were measured and correlated with differences in quantifications of stenosis grade between QCA and CTCA. A total of 113 coronary stenoses were detected by both methods (94 significant and 19 non-significant); 52 stenoses were rated as non-calcified and 61 as calcified lesions. The mean difference between QCA and quantitative CTCA grading was 5.1+/-16.9% (range -27 to 46%) overall; 1.9+/-14.2% (range -27 to 38%) for non-calcified lesions and 7.8+/-18.6% (range -23 to 46%) for calcified lesions. Mean vessel attenuation was 362+/-76 HU (range 191-584 HU) in the LMA and 333+/-81 HU (range 162-564 HU) in the RCA. Attenuation did not significantly correlate with differences in QCA and CTCA gradings, neither overall nor for calcified or non-calcified lesions. When 64-slice CTCA is used, coronary vessel attenuation had no impact on the quantitative grading of stenoses.

Low-dose CT coronary angiography in the step-and-shoot mode: diagnostic performance.

OBJECTIVE: To investigate the performance of low-dose, dual-source computed tomography (DSCT) coronary angiography in the step-and-shoot (SAS) mode for the diagnosis of significant coronary artery stenoses in comparison with conventional coronary angiography (CCA). DESIGN, SETTING AND PATIENTS: Prospective, single-centre study conducted in a referral centre enrolling 120 patients (71 men, mean (SD) age 68 (9) years, mean (SD) body mass index 26.2 (3.2) kg/m2). All study participants underwent DSCT in the SAS mode and CCA within 14 days. Twenty-seven patients were given intravenous beta blockers for heart rate reduction before CT. Patients were excluded if a target heart rate 50%) stenoses. Sensitivity, specificity, negative (NPV) and positive predictive values (PPV) were determined, with CCA being the standard of reference. Radiation dose values were calculated. RESULTS: DSCT coronary angiography in the SAS mode was successfully performed in all 120 patients. Mean (SD) heart rate during scanning was 59 (6) bpm (range 44-69). 1773/1803 coronary segments (98%) were depicted with a diagnostic image quality in 109/120 patients (91%). The overall patient-based sensitivity, specificity, PPV and NPV for the diagnosis of significant stenoses were 100%, 93%, 94% and 100%, respectively. The mean (SD) effective dose of the CT protocol was 2.5 (0.8) mSv (range 1.2-4.4). CONCLUSIONS: DSCT coronary angiography in the SAS mode allows, in selected patients with a regular heart rate, the accurate diagnosis of significant coronary stenoses at a low radiation dose.

Interactive visuo-haptic surgical planning tool for pelvic and acetabular fractures.

Treatment of pelvic and acetabular fractures still poses a major challenge to trauma surgeons. We present a tool for intervention planning for such injuries using patient-specific models built from Computed Tomography data. The presented tool has three main parts: (1) the virtual reduction of the bone fragments, (2) the virtual adaptation of the osteosynthesis implants and (3) Finite Element Analysis (FEA) for testing mechanical behavior of the resulting intervention plan. Our tool provides an intuitive visuo-hapic interface designed to be used by trauma surgeons. The type and size of the osteosynthesis material can be determined and measurements like distances and angles relative to landmarks can be taken. First results of prospectively planned interventions show an excellent correlation and a significant gain in operation time.

Combining dual-source computed tomography coronary angiography and calcium scoring: added value for the assessment of coronary artery disease.

OBJECTIVE: To prospectively investigate the diagnostic accuracy of dual-source 64-slice computed tomography coronary angiography (CTCA), calcium scoring (CS) and both methods combined for assessing significant coronary artery stenoses relative to conventional coronary angiography (CCA). DESIGN, SETTING AND PATIENTS: Prospective, single-centre study conducted in a referral centre enrolling 74 consecutive patients (24 women; mean age 62 (SD 12) years) from August-October 2006. All study participants underwent CS, CTCA and CCA. Diagnostic accuracy was calculated for CS, CTCA and both methods combined relative to CCA. Not-evaluative segments at computed tomography were considered false positive. RESULTS: CCA identified 139 stenoses in 36 patients. Average heart rate during CTCA was 68 (13) bpm (range 35-102 bpm), and 2% of segments (21/1001) in 11% of patients (8/74) were not evaluative. Considering these as false positives, per-patient sensitivity and specificity was 98% and 87%. When using CS cut-off values of 0 to exclude and >or=400 to predict stenosis, sensitivity and specificity of CS was 100% and 70%, respectively. Combining CS and CTCA in all patients correctly reclassified five patients, while six were falsely classified as stenotic, all of them correctly classified with CTCA alone. Using CS only in patients with not-evaluative segments correctly reclassified five patients while avoiding misclassifications (sensitivity 98%, specificity 100%). CONCLUSION: Dual-source CTCA allows the diagnosis of significant stenoses with a high diagnostic accuracy. Selectively combining CS with CTCA in patients with not-evaluative coronary segments improves specificity from 87% to 100% without decreasing the high sensitivity of 98%.

[Simulation of blood flow within the abdominal aorta. Computational fluid dynamics in abdominal aortic aneurysms before and after interventions]. / Simulation des Blutflusses in der abdominellen Aorta. Die numerische Simulation des Blutflusses in abdominellen Aortenaneurysmen vor und nach Intervention.

The goal of numeric analysis of aortic blood flow is to evaluate the mechanisms leading to an aortic aneurysm with regard to the risk of a rupture and to describe the effect of interventional therapy. Numeric analysis is based on virtual models of vascular structures and the physical characteristics of the vessel wall, of blood as fluidum, and the blood flow. Using this information, numeric analysis solves the appropriate equations. The results can be displayed quantitatively and qualitatively. The results of numeric flow simulation show that in abdominal aortic aneurysms the wall pressure, which is of vital importance for the risk of rupture, depends on several factors, one being the location of the intraluminal thrombus. In models of aneurysms after stent grafting, numeric analysis can be used to evaluate factors leading to stent migration. Although numeric analysis of aortic blood flow still has several limitations, recent studies have shown that this method has the potential for improved estimation of the rupture risk of aortic aneurysms in the near future.

Pseudoaneurysm in the iliac fossa after renal transplantation--treatment with ultrasound-guided thrombin injection.

We report the case of a 57-year-old female who developed a large pseudoaneurysm of the right circumflex iliac artery 15 months after renal transplantation. Minimal invasive treatment was successfully performed with ultrasound-guided thrombin injection using the B-flow mode.

State of the art 3D imaging of abdominal organs.

Since its introduction in the late 70's 3D imaging has assumed growing importance for the visualization of abdominal pathologies. Main clinical applications include the preoperative planning for resection of liver, pancreas and kidney tumors, living-donor liver and renal transplantation, and tumor radiofrequency ablation of liver and kidney. The advantages of 3D imaging are the exact visualization of vessels in areas with complex and variable vascular anatomy, demonstration of possible resection margins, and predicting operative risks, especially when dealing with complex or minimal invasive surgery. 3D imaging is an important visual aid for the surgeon in order to facilitate crucial decisions and to lower the operative risk. In future, 3D planning and simulation of operations will be become standard procedures. Therefore an efficient use of 3D imaging is not possible without a close collaboration between radiologist and surgeons.

[Influence of body mass index on coronary artery opacification in 64-slice CT angiography]. / Einfluss des Bodymass-Index auf den Kontrast in den Koronararterien mit der 64-Schicht-CT.

PURPOSE: To evaluate the influence of the body mass index (BMI) on coronary artery opacification in 64-slice CT. MATERIAL AND METHODS: Sixty-two patients retrospectively underwent ECG-gated 64-slice CT coronary angiography (tube potential 120 kV, tube current time product 650 mAs) after intravenous injection of 80 ml of iodinated contrast agent (320 mg/ml, 5 ml/s). Attenuation values (HU) were measured and contrast-to-noise ratios (CNR) were calculated in the right coronary artery (RCA) and left main artery (LMA). The CNR was defined as the difference between the mean attenuation in the vessel and the mean attenuation in the perivascular fat tissue divided by the image noise in the ascending aorta. The height and weight of the patients at the time of the CT scan were recorded and the BMI was calculated. RESULTS: The mean BMI was 26.2 +/- 3.2 kg/m (2) (range 19.7 - 32.2 kg/m (2)), the mean attenuation in the LMA was 330 +/- 64 HU, and the mean attenuation in the RCA was 309 +/- 68 HU. The CNR in the LMA was 16.7 +/- 3.8, and the CNR in the RCA was 15.9 +/- 3.6. The image noise in the ascending aorta significantly correlated with the BMI (r = 0.36, p < 0.01). A weak negative correlation was found between the BMI and LMA attenuation (r = - 0.28, p < 0.05), whereas no significant correlation was found for the RCA (r = - 0.21, p = 0.12). A significant negative correlation was found between the BMI and the CNR in the RCA (r = - 0.41, p < 0.05) and the LMA (r = - 0.47, p < 0.001). CONCLUSION: With constant scan parameters and a constant contrast medium amount, the CNR in both coronary arteries decreases while the BMI increases. This implies a modification of previously standardized and fixed examinations with respect to individually adapted protocols with variable parameters for CT coronary angiography.

[Non-invasive assessment of the perfusion of wounds using power Doppler imaging: vacuum assisted closure versus direct wound closure]. / Beurteilung der Perfusion vakuumversiegelter Wunden mittels Power Doppler.

AIM: The goal of our study was to assess the perfusion in wounds treated by vacuum assisted closure (VAC) compared to primary wound closure. METHOD: Power Doppler Ultrasound (PDUS) was carried out under standardised conditions in 15 VAC-treated and 10 primarily closed wounds as well as on altogether 25 intraindividual reference areas. All data were sent to a work station for post-processing to determine the perfused area. Statistical data analysis was performed with the Mann-Whitney test. RESULTS: Both VAC-treated wounds and primarily closed wounds showed a significant increase of the perfusion when compared to the intraindividual reference area (p < 0.0001). In VAC-treated wounds, a markedly increased perfusion was measured compared to the wounds closed primarily (p < 0.0001). Perfusion decreased during treatment, but in two VAC-treated wounds, an initial increase of the perfusion was observed. Both these wounds were grossly infected. CONCLUSION: PDUS allows the quantification of the differences in wound perfusion. This can be helpful in the detection of progressive local wound infections.

Coronal ultra-thick multiplanar CT reconstructions (MPR) of the pelvis in the multiple trauma patient: an alternative for the initial conventional radiograph.

PURPOSE: Multiple trauma patients with clinically suspected pelvic fractures often directly undergo a CT scan. However, the initial portable pelvis film (PPF) for further follow-up is then not available. This study examines whether coronal ultra-thick multiplanar reconstructions from CT data are similar when compared with the initial PPF, thus having the potential to serve as an alternative baseline image. MATERIALS AND METHODS: Initial PPF and coronal ultra-thick multiplanar CT reconstructions of 33 multiple trauma patients with pelvic fractures were retrospectively analyzed by two independent radiologists with regard to image quality, visualization of anatomical landmarks, and diagnostic accuracy. The primary diagnosis of pelvic fractures was made by using thin axial CT images and thin slice coronal and sagittal reconstructions and served as the standard of reference. RESULTS: Coronal ultra-thick multiplanar CT reconstructions were superior to PPF regarding image adjustment (p < 0.02), absence of overlaying structures (p < 0.05), and overall image quality (p < 0.01). Visualization of most anatomical landmarks was similar with both modalities, except of the iliosacral joint and acetabular lines which were more accurately depicted on ultra-thick multiplanar CT reconstructions (p < 0.05). Diagnostic accuracy of coronal ultra-thick CT reconstructions was similar to PPF regarding most fracture types, except of a higher accuracy of coronal ultra-thick CT reconstructions for iliosacral joint and acetabular column fractures (p < 0.05). CONCLUSION: Coronal ultra-thick multiplanar CT reconstructions of the pelvis provide similar image quality and diagnostic accuracy compared to PPF and are therefore suited as alternative baseline image in multiple trauma patients who directly undergo CT.

[Diagnostic assessment of painless microhematuria: prospective study comparing image quality, assessibility and diagnostic certainty of multidetector-row CT and intravenous pyelography within a single examination]. / Diagnostische Abklärung der schmerzlosen Mikrohämaturie: Prospektive Studie zum Vergleich von Bildqualität, Beurteilbarkeit und diagnostischer Sicherheit von MDCT und IVU in einem Untersuchungsgang.

PURPOSE: The purpose of this study is to prospectively compare intravenous pyelography (IVP) and combined unenhanced and excretory phase multidetector-row CT (MDCT) with respect to image quality, diagnostic certainty and diagnostic concordance with the final clinical diagnosis in patients with painless microhematuria. MATERIALS AND METHODS: Unenhanced MDCT, IVP and excretory phase MDCT were performed in 59 consecutive patients (21 women, 38 men, mean age 56 +/- 19 years, range 23 - 83 years) with painless microhematuria of unknown origin during a single examination with a single contrast media application (100 ml, non-ionic iodinated contrast media). Images were assessed by two experienced urogenital radiologists in consensus for image quality, diagnostic certainty of stone detection, obstruction, parenchymal lesions and morphological distinctive features. Imaging diagnoses of MDCT and IVP were compared with the final clinical diagnoses. In case of failure to detect an relevant pathology, the final clinical diagnosis was established after a mean follow-up period of 18 +/- 6 months (10 months to 2 years). Costs and radiation exposure of IVP and MDCT were compared. RESULTS: MDCT scan performed better than IVP in terms of image quality for all regarded variables. Image quality of MDCT was rated in all parameters as very good or good; the image quality of IVP differed in a wide range. MDCT and IVP reached a sensitivity of 100 % and 50 % for stone detection (n = 14, p = 0.008), respectively. Two bladder stones were not detected by IVU but correctly seen with MDCT. MDCT and IVP were unsatisfactory for detecting transitional cell carcinomas (n = 4, 2 of 4 detected with MDCT, 0 of 4 detected with IVU). One false positive transitional cell carcinoma was detected with IVP, none with MDCT. Additional relevant pathological changes (one teratoma, one abdominal aortic aneurysma and one abscess) were detected using MDCT but missed with IVP. In 38 of 59 patients (64 %) imaging and clinical follow-up over up to 24 months did not reveal any pathology to explain the microhematuria. The costs of the IVP (283 Euro) were lower compared with non-enhanced MDCT (380 Euro) or combined non-enhanced and contrast-enhanced MDCT (560 Euro). The radiation exposure was 23 - 27 mSv for MDCT and 2.3 mSv for IVP. CONCLUSION: MDCT performed better regarding image quality, subjective diagnostic certainty and diagnostic results with respect to stone detection. Since urolithiasis is a frequent cause of painless microhematuria MDCT is recommended as the initial imaging modality rather than IVU.