Nils Hackstein

Measurement of single-kidney glomerular filtration rate using a contrast-enhanced dynamic gradient-echo sequence and the Rutland-Patlak plot technique.

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.

Glomerular filtration rate measured using the Patlak plot technique and contrast-enhanced dynamic MRI with different amounts of gadolinium-DTPA.

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° 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. Pearsons 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. J. Magn. Reson. Imaging 2005.

Diagnostic Value of Magnetic Resonance Imaging in Peyronie’s Disease—A Comparison Both with Palpation and Ultrasound in the Evaluation of Plaque Formation ☆

OBJECTIVE To compare the value of magnetic resonance imaging (MRI) with palpation and ultrasound in the evaluation of plaque formation in Peyronies 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 Peyronies 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.

Effect of IV Injection of Radiographic Contrast Media on Human Renal Blood Flow

OBJECTIVE. The purpose of our study was to assess the effect of an IV 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...

Iopromide one-sample clearance as a measure of glomerular filtration rate

Objective: The pharmacokinetics of iopromide were analysed using a two‐compartment model. The optimal point of time for blood withdrawal for calculation of a one‐sample clearance was determined.