OBJECTIVE:The purpose of our study was to assess the effect of an i.v. injection of iodinated radiographic contrast medium on human renal blood flow using cine phase-contrast MRI.SUBJECTS AND METHODS:We examined 12 healthy adult volunteers. Blood flow in one renal artery was measured using cine phase-contrast imaging (1.5-T MR system). Each volunteer received 120 mL of isotonic sodium chloride on study day 1 and 120 mL of a low-osmolar, nonionic, iodinated contrast medium (iomeprol, 400 mg I/mL) on study day 2. Repetitive measurements were performed before (up to five measurements in 5 minutes) and after (up to 13 measurements in 30 minutes) the injection was started.RESULTS:Mean basal renal artery blood flow was 664 mL/min. In response to the injection of the test substances, we found a significantly larger decrease in average renal blood flow for contrast medium than for sodium chloride (31.9 mL/min vs 18.3 mL/min, p = 0.0481). Furthermore, in analyzing the measurements at early time points, we found a significant decrease (11.4% +/- 4.7% [SD]; Bonferroni-corrected, p < 0.05) in renal blood flow 2 minutes after the injection of the contrast medium was started. Sodium chloride did not produce a significant effect at any time.CONCLUSION:Cine phase-contrast MRI can measure a decrease in renal blood flow in humans in response to an i.v. injection of iodinated radiographic contrast medium. Therefore, cine phase-contrast MRI can be a helpful and noninvasive tool for further investigations of contrast media-induced changes in human renal blood flow and their possible impact on the development of contrast-induced nephropathy.

PURPOSE:To present a method for calculating split renal function solely from routine triphasic helical computed tomography (CT). SUBJECTS AND METHODS:We retrospectively included 26 adult patients who received renal scintigraphy and triphasic CT within 4 weeks in the years 2003 and 2004. All scans were performed using a standard abdominal protocol. Split renal function was calculated as relative single-kidney glomerular filtration rate (GFR) using a simplified "two-point Patlak plot" technique. As a reference method, split renal function was determined from renal scintigraphy using the standard technique. RESULTS:Linear correlation between the two methods was r=0.91, split renal function (CT)=0.0266+0.9573 x split renal function (scintigraphy). CONCLUSION:Split renal function can be measured accurately by minimally extended triphasic CT.

Ziele: Bestimmung der optimalen Gd-DTPA Menge und des optimalen Zeitfensters zur Messung der glomerulären Filtrationsrate (GFR) mittels dynamischem, kontrastunterstütztem MRT. Methode: Zwölf gesunde Probanden mit normaler Nierenfunktion wurden eingeschlossen. Als Referenzverfahren wurde die GFR mittels Niedrig-Dosis Iopromid Plasmaclearance bestimmt. Für die MRT Messung wurde eine 3D GRE Sequenz mit einem Flipwinkel von 50 Grad mit 14 axialen Schnitten mit einer Schichtdicke von 12mm und einer Messdauer von 4.55 Sekunden eingesetzt. Diese Sequenz wurde 40 mal wiederholt. An vier Studientagen wurden 2 mL, 4 mL, 8 mL oder 16 mL Gd-DTPA 0.5 mmol/mL injiziert.Aus den MRT Bildern wurden Signalkurven für Aorta und beide Nieren erstellt. Hieraus wurde mit dem Patlak Plot Verfahren die Steigung berechnet, die hypothetisch der GFR entspricht. Es wurde eine Korrekturfaktor zur Kompensation der verschiedenen Relaxivitäten in Urin und Plasma verwendet. Ergebnis: Mittlere Referenz-GFR war 133 mL/min (min-max 116–153 mL/min). Die beste Übereinstimmung fand sich mit der 16 mL Gruppe im Zeitfenster 30–90 sekunden nach Signalanstieg in der Aorta. Der Korrelationskoeffizient Betrug r=0,83, SD=10,5 mL/min, mittlere GFR war 118 mL/min. Schlussfolgerung: Die dynamische MRT liefert mit dem vorgestellten Protokoll eine gute Übereinstimmung der berechneten GFR mit dem Referenzverfahren.

We determined the optimum gadolinium (Gd)-DTPA dose and time window for calculating the glomerular filtration rate (GFR) using contrast-enhanced (CE) dynamic MRI and the Patlak plot technique. Twelve adult volunteers with healthy kidneys were included in the study. As a reference method the GFR was measured by iopromide plasma clearance. A three-dimensional gradient-echo (GRE) sequence with a flip angle of 50 degrees was used for MRI. Signal was measured using a body surface coil with four elements. Each volunteer was examined on four days using 2 mL, 4 mL, 8 mL, or 16 mL of Gd-DTPA 0.5 mmol/mL dissolved with sodium chloride (NaCl) 0.9% to a total of 60 mL. The injection rate was 1 mL/second. A Patlak plot was calculated from the kidney and aorta signals. The mean reference GFR was 133 mL/min (min-max, 116-153 mL/min). The best correlation of GFR calculated from MRI data compared to the reference method was found in a time window 30-90 seconds after aortic signal rise using 16 mL Gd-DTPA. Pearson's correlation coefficient was r = 0.83, and the standard deviation (SD) from the line of regression was 10.5 mL/minute. We found a significantly lower average GFR(MR) using 16 mL Gd-DTPA compared to 4 mL and 2 mL in the late time window 60-120 seconds post aortic rise. A dose of 16 mL Gd-DTPA was optimal for measuring GFR using dynamic MRI and the Patlak plot technique. The slope should be measured in a time window of 30-90 seconds post aortic rise.

PURPOSE:To determine the accuracy of the two-point Patlak plot in the calculation of glomerular filtration rate (GFR).MATERIALS AND METHODS:Fifty patients without acute renal disorder were included. GFR was calculated by using a two-point Patlak plot technique. The computed tomography (CT) protocol consisted of a plain examination followed by two contrast material-enhanced examinations in the arterial and portovenous phase. Each examination included the entire kidneys and was performed after injection of 120 mL iopromide and 300 mg of iodine per milliliter given per 75 kg of body weight. All examinations were performed with a standard abdominal protocol. Section thickness was 4 x 2.5 mm, and table advance was 12.5 mm. Bolus triggering commenced 10 seconds after the start of contrast medium injection. Twelve dynamic scans were obtained with reduced tube current every 3 seconds to obtain sufficient arterial input function data. Correction for hematocrit level was made by using the unenhanced attenuation of the aorta. As a reference method, plasma clearance of the contrast medium injected for CT was calculated from three iodine plasma concentration measurements obtained 3, 4, and 5 hours after injection. Linear correlation was performed.RESULTS:GFR was calculated from CT data in 48 patients. Two patients were excluded because of breathing errors. Mean GFR was 80 mL/min (range, 17-153 mL/min) as measured with iopromide plasma clearance and 82 mL/min (range, 28-148 mL/min) as measured with CT. Linear correlation between the two methods was r = 0.889; GFR calculated with the two-point Patlak plot was equal to 15 plus 0.83 times GFR (plasma clearance). The mean difference between GFRs as determined with the two methods was -1.2 mL/min (95% CI: -27.1, 24.6).CONCLUSION:Total GFR can be measured accurately with minimally extended triphasic CT in patients without acute renal disorder by using a two-point Patlak plot technique.

Insulin independence after islet transplantation has been significantly improved by using new steroid-free immunosuppressive protocols and increased islet mass. Only little is known about the influence on the morphology of the liver of intraportally transplanted islets. We describe a case of disseminated periportal fatty degeneration after allogeneic intraportal islet transplantation (ITx). A 35-year-old patient with type-1 diabetes mellitus who was suffering from repeated severe hypoglycemic episodes received two sequential intraportal islet grafts. Liver structure was normal before the first ITx, based upon ultrasound and magnetic resonance imaging (MRI). One week after the first ITx, ultrasound demonstrated normal liver morphology. Four months later, at the second ITx, we detected small, disseminated, and hypodense hepatic lesions (1 to 3 mm) by ultrasound, which were confirmed by MRI and interpreted to be fatty degenerations. Histologically we found focal drop-shaped fatty degenerations with signs of mild periportal chronic inflammation. These liver alterations without clinical symptoms or pathological liver function tests matched the predicted distribution of infused islets. Glucose metabolism markedly improved after the first ITx, namely 58.6% reduction of daily insulin requirements, 1.4% decrease in HbA1c, basal C-peptide of 0.8 to 1.3 ng/dl with no severe hypoglycemia. We interpreted these benign changes in liver morphology as reactions to a local hyperinsulinemia in the neighborhood of the transplanted islets. We hypothesized that a steroid-free immunosuppression with rapamycin and tacrolimus may have contributed to changes in the portal microenvironment.

Ziele: Messung der Einzelnieren-GFR mit Hilfe der Patlak-Plot Technik anhand eines dynamischen, kontrastverstärkten MRT Methode: 28 Patienten wurden eingeschlossen. Als Referenzmethode wurde die GFR mit Hilfe der Iopromid Plasmaclearance bestimmt. Hierzu wurden 12ml Iopromid (Ultravist 300) injiziert und die Jodkonzentration im Plasma nach 3, 4 und 5 Stunden gemessen. Für das dynamische MRT wurde eine 3-D Gradienten-Echo Sequence mit einem Flip-Winkel von 50 Grad durchgeführt. Diese Sequenz zeigte in Phantommessungen eine gute Linearität zwischen MRT-Signal und einer Gadoliniumkonzentration von unter 10 mmol/l. Mit dem MRT wurde ein Volumen gemessen, welches beide Nieren und die Aorta enthielt. Die Messung wurde 30 mal über einen Zeitraum von ca. 3.5 Minuten wiederholt. Bei Beginn der MRT-Messung wurden 15ml Gd-DTPA 0.5 mol/l (Magnevist, Schering AG) verdünnt auf ein Volumen von 60ml über 60 Sekunden injiziert. Anhand der gemessenen Signalstärken in Nieren und der Aorta wurde die Einzelnieren-GFR anhand einer Patlak Plot Berechnung ermittelt. Die Summe der Einzelnieren-GFR Bestimmung aus den MRT Daten wurde mit der Plasmaclearance von Iopromid verglichen Ergebnis: Die beste Übereinstimmung mit dem Referenzverfahren fand sich für die Patlak Plot Berechnung mit einem Zeitfenster von 40 bis 110 Sekunden nach initialem aortalen Signalanstieg. Pearson"s Korrelationskoeffizient war r=0.86, SD war 14.8ml/min. In vielen Patienten fand sich ein Abfall des Nierensignals in der Ausscheidungsphase, der wahrscheinlich durch T2* Effekte durch sehr hohe Gadoliniumaufkonzentrierungen in den Sammelrohren bedingt war. Schlussfolgerung: Die Einzelnieren GFR kann mit Hilfe eines dynamischen, kontrastunterstützten MRT gemessen werden. Wir fanden eine vielversprechende Übereinstimmung mit dem Referenzverfahren, welches die globale GFR maß. In zukünftigen Studien sollte die Methode dahingehend verbessert werden, dass die unerwünschten T2* Effekte durch zu hohe Gd-Konzentrationen umgangen werden.

PURPOSE: To evaluate the feasibility of micro computed tomography (CT) for analysis of the coronary artery wall.MATERIALS AND METHODS: With micro CT, two-dimensional transverse images were generated from 10 human autopsy specimens of coronary arteries (2.5-3.5 cm long), with section thickness of 6 mum. Vessel wall perimeter, plaque area, calcified lesion area, media area, and lumen area were determined by three experienced radiologists. Results were compared with those obtained from a detailed conventional histomorphometric analysis of corresponding cross sections. Hotelling T-2 test (a multivariate generalization of the univariate Student t test) and Pearson correlation coefficient were used to assess the correlation between micro CT findings and conventional histologic measurements. The significance of differences in gray-scale measurements was tested with analysis of variance.RESULTS: Micro CT provided quantitative information about plaque morphology 2 equivalent to that provided with histomorphometric analysis. Hotelling T-2 test revealed significantly smaller values for vessel wall perimeter and lumen area with histologic sections (P < .001). Gray-scale measurements were established with which lesions could be categorized after histologic classification.CONCLUSION: Micro CT is feasible for analysis of the coronary artery wall. (C) RSNA, 2004.

Ein 47-jähriger Patient stellte sich über die internistische Notaufnahme mit zunehmender Luftnot und rechtsseitigem Thoraxschmerz vor. Von dem Patienten war in einem 2 Jahre alten Vor-CT eine unklare Verdichtung des mediastinalen Fettgewebes diagnostiziert worden, die aber nicht weiter abgeklärt worden war (Abb. [1]). Des Weiteren waren alte Verschlüsse beider Venae brachiocephalicae bei Protein-S-Mangel bekannt.

We present the case of a 22-year-old patient who had splenectomy in childhood after trauma and had a known chronic active infection with hepatitis C. Imaging procedures in different radiologic modalities diagnosed diffuse intraabdominal splenosis. Splenosis is a rare, severe complication of splenic trauma or surgery, but the pathogenesis is not clear. Imaging features play a key role in the diagnosis of ectopic splenic tissue, which must be differentiated from malignancies, especially from lymphoma. Splenosis itself may induce relapse of hematologic diseases, mainly autoimmune thrombocytopenia.

OBJECTIVE We measured the single-kidney glomerular filtration rate (GFR) with a two-point Patlak plot technique based on multiphasic CT in patients with hydronephrosis or pyelonephritis or both. The question we sought to answer in our study was, Does increased interstitial space as measured with the Patlak plot technique cause overestimation of GFR? SUBJECTS AND METHODS Twenty adult patients treated with percutaneous nephrostomy were studied. The CT protocol consisted of an unenhanced scan and three subsequent scans obtained 38, 71, and 102 sec after the initiation of the contrast medium injection. Plasma clearance of the contrast medium was determined and used as the reference. Additionally, single-kidney excretory clearance was determined by separate urine collections from the left and right kidneys. A three-compartment model calculation was made using all data available to estimate volume and transfer rate constant of the interstitial space. RESULTS The GFR determined using plasma clearance correlated well with the GFR determined using excretory clearance, with a correlation coefficient of r = 0.94 and a regression line of y = -6 + 0.97 x x. GFR of both kidneys as measured using CT was overestimated according to the GFR determined using plasma clearance, with a correlation coefficient of r = 0.80, and a regression line of y = 35 + 0.79 x x. Single-kidney excretory clearance GFR was similarly overestimated using single-kidney CT GFR, with a correlation coefficient of r = 0.81 and a regression line of y = 20 + 0.84 x x. Single-kidney parenchymal volume was used as an indicator of interstitial space enlargement. The overestimation of excretory clearance GFR using CT correlated significantly with the parenchymal volume of the individual kidneys. A high correlation was also found between overestimation of total GFR determined with CT and interstitial space estimated using a three-compartment model calculation. Relative interstitial space was estimated to be 25% (range, 9-46%) of total kidney volume. CONCLUSION Using the interstitial space as a third compartment may introduce an error into the measurement of GFR with the Patlak plot technique. We found that the CT protocol in our study resulted in considerable overestimation of GFR as determined with the Patlak plot in patients with increased interstitial space.

PURPOSE:To determine the accuracy of single-kidney glomerular filtration rate (GFR) determination using contrast-enhanced dynamic magnetic resonance imaging (MRI) and the Rutland-Patlak plot technique.MATERIALS AND METHODS:Twenty-eight adult patients were included. As reference method, the GFR was measured by plasma clearance using a small bolus injection of iopromide. A three-dimensional gradient-echo (GRE) sequence with a flip angle of 50 degrees was used for MRI; this showed a good linear relationship between gadolinium (Gd)-DTPA concentration and signal change when measured up to a Gd-DTPA concentration of 10 mmol/liter. A slab containing both kidneys and the abdominal aorta was measured 30 times in approximately 3.5 minutes. During this measurement, 15 mL of Gd-DTPA, 0.5 mol/liter diluted to a volume of 60 mL, was injected over 60 seconds. A Rutland-Patlak plot was calculated from the signal changes in the aorta and the renal parenchyma. Single-kidney GFR was calculated for different time windows from the Rutland-Patlak plot slope.RESULTS:The best correlation compared to the reference method was found with the GFR calculated from the slope of the Rutland-Patlak plot 40-110 seconds postaortic rise. Pearson's correlation coefficient was r = 0.86, SD was 14.8 mL/minute. In many of the patients, a decrease of the renal signal was observed in the excretory phase, which was probably caused by very high Gd-DTPA concentrations in the collecting tubules.CONCLUSION:Single-kidney GFR can be calculated from dynamic contrast-enhanced MRI. We found a promising correlation of global GFR calculated by MRI compared to the reference method. In any future study, the amount of Gd-DTPA should by reduced to avoid artificial signal drop in the excretory phase induced by the T2* effect.

Bei Patienten mit einem akuten Abdomen wird häufig ein CT zur diagnostischen Abklärung eingesetzt. Wir berichten im Folgenden über einen Fall mit gastrointestinaler Manifestation eines hereditären Angioödems, welches sich klinisch als akutes Abdomen präsentierte.

OBJECTIVE:To compare the value of magnetic resonance imaging (MRI) with palpation and ultrasound in the evaluation of plaque formation in Peyronie's disease.METHODS:57 patients underwent a standardized diagnostic procedure to evaluate plaque formation consisting of palpation and ultrasonography (7.5 MHz). MRI was performed during flaccidity and during erection induced by Prostaglandin E(1) including intravenous application of Gadolinium-diethylenetriaminepentaacetic acid (Gd-DPTA).RESULTS:With all methods, 93 plaques have been detected in 57 patients. 85 plaques (91.4%) have been evaluated by palpation alone. Using ultrasound, 52 of these 93 plaques (55.9%) were detectable. This is equivalent to 61.1% of the palpable plaques. MRI confirmed 58 of the palpated plaques (68.2%) and exposed 8 primarily not palpable plaques at the penile basis. MRI revealed more palpable plaques than ultrasound, but this finding was not significant (p = 0.083). By means of sonography, calcification was evident in 14 plaques. MRI failed in revealing any calcification. After application of Gd-DPTA, 5 of 57 patients (9%) demonstrated contrast enhancement indicating local inflammation. None of these patients reported on penile pain.CONCLUSIONS:Penile palpation in combination with ultrasound represents the method of choice to diagnose plaque formation in Peyronie's disease. MRI provides better information on plaque formation at the penile basis. Calcification can only be proven by ultrasound, not by MRI. There may be additional information by MRI about local inflammation. A prospective study comparing the histological and MRI findings should be performed to answer the question, if pain is really associated with inflammation.

PURPOSE:Glomerular filtration rate (GFR) can be measured by iopromide plasma clearance. As an injection of 120 ml nonionic contrast medium is expensive and especially in patients with nephropathy potentially nephrotoxic, we investigated whether iopromide plasma clearance could be measured using a tenth of that dose as 'low-dose' clearance.MATERIAL AND METHODS:Fifty adult patients scheduled for CT were recruited. Iopromide 300 mg I/ml was used for GFR measurement. Prior to CT, low-dose clearance was measured by injecting 12 ml iopromide per 75 kg b.w. At 3, 4 and 5 h after injection, plasma samples were obtained and the iodine concentration was measured by X-ray fluorescence analysis. Immediately after the last blood sample, CT was again performed following injection of 120 ml iopromide per 75 kg b.w. A further 3 plasma samples were then obtained 3, 4, and 5 h after CT and used for the determination of high-dose clearance.RESULTS:Low-dose clearance ranged from 20 ml/min to 141 ml/min (mean 78.3 ml/min). High-dose and low-dose clearance correlated excellently, with clearance (high-dose) = 1.4 + 0.994 clearance (low-dose); the correlation coefficient was r = 0.944, the standard deviation SDxy= 9.3 ml/min.CONCLUSION:Plasma clearance of iopromide is dose-independent on use of iodine amounts of 3.6 g and 36 g I/75 kg b.w. The GFR can be determined by high-dose and low-dose iopromide plasma clearance with identical accuracy.

We report on a case of penile epithelioid sarcoma in a 29-year-old man presenting with a dorsal penile plaque that primarily was misdiagnosed as Peyronie's disease. Although the initial clinical findings of these two different entities appear similar, the consequence for the patient is severe. The only way of differentiating these disorders are histological findings. The principal microscopic characteristics of epithelioid sarcoma are the distinctive nodular arrangement, central degeneration and necrosis of the tumor cells with epithelioid appearance and eosinophilia. Immunohistochemical data (cytokeratin, epithelial membrane antigen, vimentin, CD 34, desmin) confirm the diagnosis. We conclude that in cases with slightest doubts on the diagnosis of Peyronie's disease, especially in younger men suffering from a fast-growing penile induration, a bioptic clarification of the entity should be performed to exclude a high malignant disease that can be only treated as far as it is localized by radical surgery.

In the present study, we investigated a new sonographic test to confirm or exclude partial common bile duct (CBD) obstruction, hereinafter called "dynamic cholangio-cholecysto sonography (DCCS)." Healthy controls (6) and patients with low- to intermediate probability for partial CBD obstruction (17) were investigated. DCCS started with three baseline masurements of gallbladder volume and CBD diameter, which were then repeated every 2 to 3 min for 45 min during a 30-min infusion of ceruletid. According to CBD diameter change during gallbladder contraction, DCCS was considered positive (> 1 mm), negative (< 0.5 mm) or equivocal (remainder). After DCCS, all patients underwent endoscopic retrograde cholangiography (ERCP) and all but one patient had endoscopic sphincterotomy (EST). A follow-up examination was performed at least 4 weeks after ERCP. Based on these results, an outcome score was calculated to classify the patients as having a flow-relevant CBD obstruction or not. DCCS was true positive in 4 patients (sensitivity 66%, positive predictive value 100%). DCCS was false-negative in 1 patient and equivocal in another patient. DCCS was true-negative in 9 patients (specifity 82%, negative predictive value 90%). Two patients without flow-relevant CBD obstruction had equivocal DCCS test results. DCCS might be used as a noninvasive test for further workup of patients with low- to intermediate probability of flow relevant CBD obstruction, helping to avoid unnecessary ERCP and to serve as an additional indication for ERCP and EST.