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At least 19 recordsLinked to original sources
PubMed2004

Patient radiation dose at CT urography and conventional urography.

PURPOSE: To measure and compare patient radiation dose from computed tomographic (CT) urography and conventional urography and to compare these doses with dose estimates determined from phantom measurements. MATERIALS AND METHODS: Patient skin doses were determined by placing a thermoluminescent dosimeter (TLD) strip (six TLD chips) on the abdomen of eight patients examined with CT urography and 11 patients examined with conventional urography. CT urography group consisted of two women and six men (mean age, 55.5 years), and conventional urography group consisted of six women and five men (mean age, 58.9 years). CT urography protocol included three volumetric acquisitions of the abdomen and pelvis. Conventional urography protocol consisted of acquisition of several images involving full nephrotomography and oblique projections. Mean and SD of measured patient doses were compared with corresponding calculated doses and with dose measured on a Lucite pelvic-torso phantom. Correlation coefficient (R(2)) was calculated to compare measured and calculated skin doses for conventional urography examination, and two-tailed P value significance test was used to evaluate variation in effective dose with patient size. Radiation risk was calculated from effective dose estimates. RESULTS: Mean patient skin doses for CT urography measured with TLD strips and calculated from phantom data (CT dose index) were 56.3 mGy +/- 11.5 and 54.6 mGy +/- 4.1, respectively. Mean patient skin doses for conventional urography measured with TLD strips and calculated as entrance skin dose were 151 mGy +/- 90 and 145 mGy +/- 76, respectively. Correlation coefficient between measured and calculated skin doses for conventional urography examinations was 0.95. Mean effective dose estimates for CT urography and conventional urography were 14.8 mSv +/- 90.0 and 9.7 mSv +/- 3.0, respectively. Mean effective doses estimated for the pelvic-torso phantom were 15.9 mSv (CT urography) and 7.8 mSv (conventional urography). CONCLUSION: Standard protocol for CT urography led to higher mean effective dose, approximately 1.5 times the radiation risk for conventional urography. Patient dose estimates should be taken into consideration when imaging protocols are established for CT urography.

Adult↗
PubMed2003

CT urography and MR urography.

CT urography and MR urography are an evolving concept and developing technique. As the technology matures, CT urography will combine the ultimate diagnostic capabilities of intravenous urography and CT. In the near future, many intravenous urograms will be replaced by CT urography to evaluate patients with hematuria and other genitourinary conditions. MR urography currently serves as an alternative imaging technique to intravenous urography and CT urography for children and pregnant women and for patients with contraindications to iodinated contrast media.

Contrast Media↗
PubMed2001

[Gadolinium-enhanced T(1)-weighted MR urography versus T(2)-weighted (HASTE) MR urography in children].

PURPOSE: To evaluate gadolinium-enhanced T(1)-weighted excretory MR urography (EMRU) versus T(2)-weighted (HASTE) MR urography in children with upper urinary tract abnormalities. PATIENTS AND METHODS: In a prospective study 63 children, aged from 3 weeks to 15 years, underwent MR urography in a 1.5-T scanner. Before and after an intravenous injection of 0.05 mg/kg body weight of furosemide, respiratory-triggered HASTE images were obtained for T(2)-weighted MR urography. EMRU was performed subsequent to i. v. gadolinium injection with respiratory-gated, coronal 3 D-gradient-echo sequences. RESULTS: Compared to T(2)-weighted (HASTE) MR urography, gadolinium-enhanced MR urography revealed a superior diagnostic accuracy in non-dilated collecting systems (horseshoe kidneys, ectopic kidneys, duplex systems, single ectopic ureters, ureteroceles). EMRU and T(2)-weighted (HASTE) MRU turned out to be equivalent in the assessment of obstructed but normal functioning upper urinary tracts (UPJ obstructions, megaureters). Non-functioning dilated collecting systems and multicystic dysplastic kidneys were best visualized with use of T(2)-weighted (HASTE) MR urography. CONCLUSION: Respiratory-gated gadolinium-enhanced T(1)-weighted MRU allows accurate evaluation of most upper urinary tract abnormalities. T(2)-weighted (HASTE) MRU complements GMRU in the evaluation of non-functioning renal units and cystic disease of the kidneys.

Adolescent↗
PubMed1998

Gadolinium-enhanced excretory MR urography after low-dose diuretic injection: comparison with conventional excretory urography.

PURPOSE: To evaluate the clinical utility and morphologic accuracy of gadolinium-enhanced excretory magnetic resonance (MR) urography after low-dose diuretic injection and to correlate the results with those of conventional urography. MATERIALS AND METHODS: In 71 patients with urologic symptoms, excretory MR urography was performed after intravenous injection of 5-10 mg furosemide and, 30-60 seconds later, 0.1 mmol of gadopentetate dimeglumine per kilogram of body weight. The MR urograms were interpreted by three radiologists, who were blinded to the clinical outcome, and subsequently compared with conventional urograms. RESULTS: Injection of furosemide before contrast material led to rapid, uniform gadolinium distribution inside a sufficiently distended collecting system such that there was no excessive concentration of gadolinium in the urine. In patients with normal or moderately reduced excretory function, this effect allowed complete visualization of the urinary tract within 5-20 minutes of contrast material injection while minimizing gadolinium-related endoluminal T2* effects. The clinical course helped verify almost all MR urographic results. The MR urographic technique was significantly superior to conventional urography in the assessment of the ureters and bladder (P < .0001). Delineation of small caliceal abnormalities is still problematic. The best depiction of the pelvicaliceal system was obtained with fat-suppressed MR imaging, although it was still slightly inferior to conventional urography (P < .05). CONCLUSION: Gadolinium-enhanced excretory MR urography performed after low-dose diuretic injection is a promising and accurate alternative to conventional excretory urography for imaging the morphology of the urinary tract.

Adult↗
PubMed2001

MR urography in evaluation of acute flank pain: T2-weighted sequences and gadolinium-enhanced three-dimensional FLASH compared with urography. Fast low-angle shot.

OBJECTIVE: The aim of this study was to compare the usefulness of breath-hold heavily T2-weighted sequences with gadolinium-enhanced three-dimensional fast low-angle shot (3D FLASH) MR urography in the evaluation of patients with acute flank pain. SUBJECTS AND METHODS: Forty consecutive patients with symptoms of acute flank pain underwent MR urography followed immediately by excretory urography. Heavily T2-weighted (combined thin-slice half-Fourier acquisition single-shot turbo spin-echo [HASTE] and thick-slab single-shot turbo spin-echo) and 3D FLASH sequences were evaluated separately and independently by two experienced radiologists for the presence, cause, level, and degree of obstruction. Interobserver agreement was calculated using the kappa statistic. Excretory urography and the final clinical diagnosis were used as reference. RESULTS: Twenty-six patients were found to have unilateral obstruction caused by ureteral stones. Both MR urography methods were excellent for detecting obstruction. In the detection of stones 3D FLASH was superior, with a sensitivity of 96.2% and 100% and specificity of 100% and 100% for observers A and B, respectively, compared with a sensitivity of 57.7% and 53.8% and a specificity of 100% and 100%, respectively, for T2-weighted sequences. The best degree of obstruction was seen with 3D FLASH, and the interobserver agreement was excellent for stone detection (kappa = 0.97). CONCLUSION: T2-weighted sequences alone are not sufficient for examining patients with acute flank pain. However, the combined use of both T2-weighted and 3D FLASH sequences will ensure better confidence in the evaluation of acute suspected renal colic. MR urography can replace conventional excretory urography when the latter is contraindicated or undesirable.

Acute Disease↗
PubMed2003

[MR-urography and CT-urography: principles, examination techniques, applications].

MR-urography (MRU) and CT-urography (CTU) provide refined imaging of the upper urinary tract not achievable with conventional intravenous urography (IVU). The traditional MR-urographic technique utilizes unenhanced, heavily T2 -weighted turbo spin-echo sequences for obtaining static fluid images of the urinary tract independent of the excretory renal function. T2 -weighted MR-urograms have proved to be excellent in visualizing the dilated urinary tract, even in non-excreting kidneys. In contrast, T1 -weighted MRU reflects the excretory renal function and displays the urine flow through the upper tract after renal excretion of an intravenously administered gadolinium chelate. The gadolinium-enhanced urine is visualized with fast T1 -weighted 3D-gradient-echo sequences. The combination of gadolinium and low-dose furosemide (5 - 10 mg) is the key for achieving a uniform distribution of gadolinium in the collecting system and for avoiding susceptibility artifacts (T2*-effects) in the urine. T1 -weighted excretory MRU provides impressive urograms of both non-dilated and obstructed collecting systems in patients with normal or moderately impaired renal function. Multislice-CT-urography (MS-CTU) is also an excretory urography like T1 -weighted MRU. Furthermore, MS-CTU can be combined with low-dose furosemide for accelerated passage of excreted contrast material obviating the need for abdominal compression. CT-urography is limited by its radiation burden and the nephrotoxicity of radiographic contrast media. Combining MRU or MS-CTU with conventional MRI or CT offers several applications, e.g., diagnosis of intrinsic and extrinsic tumors. Meanwhile, MRU has replaced IVU in pediatric uroradiology and is also recommended for the assessment of renal transplants. MS-CTU may provide valuable information in chronic urolithiasis, especially if associated with a distorted urinary tract anatomy. Both MRU and MS-CTU will play an important role in modern uroradiology.

Adolescent↗
PubMedDate not supplied

Utility of cine MR urography of the urinary tract and comparison with static MR urography.

PURPOSE: MR urography using heavily T2-weighted images can depict the urinary tract without the need for contrast medium. However, this technique has potential problems with regard to evaluating the non-dilated ureter. We compared the efficacy of cine MR urography (C-MRU) with static MR urography (S-MRU). MATERIALS AND METHODS: Twenty-two patients with suspected upper urinary tract disease underwent C-MRU. The final clinical diagnosis was compared with the diagnosis made using S-MRU and C-MRU, respectively. The sequence used was single-shot fast spin echo with a slice thickness of 50 mm, FOV of 45 cm, and 256x256 matrix. MR urography was obtained sequentially by 6 to 10 repetitions of single-shot scans with intermittent breath holding. S-MRU was used in the initial phase of this sequence, while C-MRU was used for the entire sequence. A final diagnosis was made based on 1) existence of stenosis, 2) rate of certainty of existence of stenosis, 3) etiology of stenosis. RESULTS: No statistically significant difference was observed between S-MRU and C-MRU, except in certainty of existence of stenosis, where C-MRU (average rate: 2.82 +/- 0.39) was significantly superior to S-MRU (2.41 +/- 0.73). CONCLUSION: C-MRU can improve the certainty of existence of urinary stenosis, and may be useful in excluding suspected stenoses in normal or undilated ureters.

Adult↗
PubMed2001

[Static-dynamic MR urography. Comparison with excretory urography and scintigraphy in experimentally-induced urinary tract obstruction].

PURPOSE: To assess the diagnostic value of combined static-dynamic MR urography (MRU) for the functional-morphological evaluation of experimentally induced urinary tract obstruction. METHODS: Static-dynamic MRU--combination study with a respiratory-triggered 3D-IR-TSE sequence and a dynamic 2D-FFE sequence after Gd-DTPA and furosemide--was obtained in comparison with 99mTc-MAG3 diuretic renal scintigraphy (DRS), excretory urography (EU) and ultrasound (US) in 29 healthy piglets and in 20 piglets with surgically induced ureteric stenosis (total of 50 postoperative examination blocks). RESULTS: MRU allowed complete depiction of the urinary tract in all controls, in operated piglets the stenosis was always correctly identified. Quality of MRU was superior to EU in 36 of 43 comparative studies. Calculation of single kidney function from parenchymal renograms, and assessment of urinary excretion from whole-kidney renograms resulted in a highly significant agreement of MRU with DRS. CONCLUSION: Static-dynamic MR urography allows excellent depiction of experimentally induced urinary tract obstruction, and reliable assessment of individual renal function and urinary excretion. Two advantages of the method stand out, it does not require radiation and it permits a functional-morphological correlation.

Animals↗
PubMedDate not supplied

Diuretic contrast-enhanced magnetic resonance urography versus intravenous urography for depiction of nondilated urinary tracts.

Diuretic contrast-enhanced magnetic resonance urography (MRU) is analogous to conventional intravenous urography (IVU) and, hence, designated as excretory MRU. It is performed with a T1-weighted fast gradient-echo sequence to obtain breath-hold, dynamic MRU after intravenous injection of low-dose furosemide (5-10 mg) and gadolinium (Gd) chelate. The combination of Gd and furosemide is the key for achieving a uniform distribution of the contrast material inside the entire urinary tract. It provides high-resolution images of nondilated urinary tracts and information about the renal function. This pictorial essay reviews the technical aspects and practical consideration of diuretic Gd-enhanced MRU and underlines its diagnostic capability in comparison with IVU in the depiction of nondilated collecting systems. We discuss its potential applications, as in young patients with anatomic anomalies, patients with renal transplants, patients allergic to iodinated contrast medium, and avoiding multimodality work-up in the evaluation of kidney donors and patients with renal and extrarenal tumor diseases.

Adult↗
PubMedDate not supplied

Effectiveness of MR urography in the evaluation of kidney which failed to opacify during excretory urography: comparison with ultrasonography.

OBJECTIVE: The purpose of this study was to compare the effectiveness of MR urography (MRU) with that of ultrasonography (US) in the evaluation of urinary tract when this failed to opacify during excretory urography (EXU). MATERIALS AND METHODS: Twelve urinary tracts in 11 patients were studied. In each case, during EXU, the urinary system failed to opacify within one hour of the injection of contrast media, and US revealed dilatation of the pelvocalyceal system. Patients underwent MRU, using a HASTE sequence with the breath-hold technique; multi-slice acquisition was then performed, and the images were reconstructed using maximal intensity projection. Each set of images was evaluated by three radiologists to determine the presence, level, and cause of urinary tract obstruction. RESULTS: Obstruction was present in all twelve cases, and in all of these, MRU accurately demonstrated its level. In this respect, however, US was successful in only ten. The cause of obstruction was determined by MRU in eight cases, but by US in only six. In all of these six, MRU also successfully demonstrated the cause. CONCLUSION: MRU is an effective modality for evaluation of the urinary tract when this fails to opacify during EXU, and appears to be superior to US in demonstrating the level and cause of obstruction.

Female↗
PubMed1981

[Intravenous urography- v.s.- ultrasonography or intravenous urography +/- ultrasonography (author's transl)].

The author warns against the abusive use of renal ultrasonography in urological disorders without previous intravenous urography investigations. It is also of fundamental importance to obtain perfect tomography images of the kidneys before requesting ultrasonography examinations, in patients with renal insufficiency. In urological practice, ultrasonography can only be correctly interpreted by the aid of anatomical data from radiological investigations, of which intravenous urography is by far the most important.

Diagnostic Errors↗
PubMed2000

Magnetic resonance urography enhanced by gadolinium and diuretics: a comparison with conventional urography in diagnosing the cause of ureteric obstruction.

OBJECTIVE: To compare the ability of magnetic resonance urography (MRU), enhanced using gadolinium and frusemide diuresis, and conventional intravenous urography (IVU) to diagnose the cause of ureteric obstruction. PATIENTS AND METHODS: The study included 82 patients in whom IVU showed or suggested obstruction and who also underwent MRU. The images from both methods were interpreted by various investigators independently; two evaluated the IVU and two others the MRU, the latter being unaware of the diagnosis after IVU. If the diagnosis remained unclear, further investigations (e.g. computed tomography, retrograde pyelography or ureteroscopy) were conducted. RESULTS: The diagnoses were ureteric calculi in 72 patients, ureteric tumours in eight and extra-ureteric tumours in two. In those with urolithiasis, the diagnosis was correct with IVU in 49 patients and with MRU in 64. The diagnosis in this group was incorrect with MRU in only two patients. The main reason for the failure of IVU was absent contrast medium excretion. Three of eight patients with ureteric tumours were correctly diagnosed by IVU but in three patients the diagnosis was incorrect. MRU correctly diagnosed seven of the eight patients in this group, with no false diagnosis. CONCLUSION: IVU is currently likely to remain the standard procedure for imaging the upper urinary tract, but this study shows the potential of MRU when enhanced with gadolinium and frusemide. MRU may be helpful if there is a dilated system with no excretory function, in pregnant women, in children and in those with contrast medium allergy.

Adult↗