Lt Klein, D Frager, A Subramanium et al
Use of Magnetic Resonance Urography.
Urology 52: 602-608, 1998.
Magnetic Resonance Urography is a new technique that uses heavily weighted T2 fast spin-echo pulse sequence coronal MR images with a rapid acquisition – relaxation enhancement to generate a high intensity signal outlining the collecting system, ureters and bladder without contrast or ionizing radiation.
The entire urinary tract can be visualized in patients with renal failure. It can detect renal cysts, carcinomas, ureteropelvic junction obstruction, diverticulum in the bladder and ejaculatory duct cyst.
MRI failed to detect non-obstructing stones visible on i.v. urograms in 2 patients in the series of 100 patients (including all the above pathologies)
MRI is a useful adjunct to other modalities, particularly in those patients for whom ionizing radiation or contrast agents are contraindicated. Improvements in resolution, technique and cost are necessary before routine MRU use is feasible.
CCA Nolte Ernsting, A Buker, GB Adam, et al
Gadolinium Enhanced Excretory Magnetic Resonance Urography After Low Dose Diuretic Injection: Comparison with Conventional Excretory Urography.
Radiology 209: 147-157, 1998.
T2 weighted MR urography yields ‘water’ images of the kidney. MRU must be performed with contrast to provide structural and functional information.
MRU was performed after i.v. injection of 5-10mg Furosemide followed by 0.1 mmol of gadopentetate dimeglumine/kg body wt. Urograms were obtained within 5-20 mins after injection of contrast.
The collecting system was well visualized and images were not affected by gas filled intestinal loops or peristalsis.
Compared with conventional excretory urography, bladder and ureter, visualization was significantly better with MRU. Procedure was well tolerated and acquisition time was less than 45 mins.
False positive rates were from 10-15%. MRU does not visualize small caliceal abnormalities as well as conventional urography.
Even with fat suppressed images, magnetic resonance images are of poorer quality to those obtained by conventional urography. In patients with renal failure ionizing radiation and contrast are not required.
CL Siegel, WD Middleton, SA Teffey et al (Washington Univ, St. Louis)
Sonography of the Female Urethra,
AJR 170:1269-1274, 1998.
Availability of small calibre, catheter based endoluminal sonographic transducers have enabled a more thorough sonographic evaluation of female urethra.
Sonography can provide important information on location and extent of diverticular neck.
Application of this technology in the general population with an otherwise low incidence of urethral diverticulum and other periurethral disease is probably not warranted at this time.
It may have a role to play in those cases when diverticulum and periurethral disease is suspected but not picked up on VCU (voiding cystourethrogram) or double balloon urethrography
MA Goldbergm WW Mayo-Smith, et al (Harvard Med. School, Boston)
FDG PET Characterisation of Renal Masses: Preliminary Experience.
Clin. Radiol 52: 510-515, 1997.
Fluorine-18, 2-fluoro-2deoxy-D-glucose positron emission tomography (FDG PET).
It is promising in the assessment of indeterminate renal cysts. A positive result in the appropriate clinical setting obviates the need for cyst aspiration.
Negative findings in conjunction with negative cyst aspiration helps to confirm that the cyst is benign. Seminomas seem to image most intensely with the modality.
FDG PET may find a place in the diagnosis of indeterminate renal masses.
S.L. Brown, DM Hoffman, J.P., Spirnak, (Case Western Reserve Univ, Cleveland, Ohio)
Limitations of Routine Spiral Computerized Tomography in the Evaluation of Blunt Renal Trauma.
J Urol 160:1979-1981, 1998.
In 3 of 35 patients (8.6%) spiral computerized tomography failed to identify injuries to the collecting system. In all 3 cases, injuries were detected on repeating the study over a period of several days based on high clinical suspicion.
This delay between scans, gives the contrast material sufficient time to image the collecting system and it ensures accurate staging and appropriate treatment of the renal injury.
K Tsuda, T Murakami, T Kim, et al (Osaka Univ, Japan)
Helical CT: Angiography of Living Renal Donors: Comparison with 3D Fourier Transformation Phase Contrast MRA.
J Comput Assist Tomogr 22: 186-193, 1998.
Introduction: In the radiological evaluation of living renal donors, renal ultrasonography, iv urography and renal conventional angiography are routinely performed. Transplantation may be made difficult by presence of accessory vessels and prehilar branches. The choice of kidney would then be affected.
Helical CT angiography is less invasive and less costly than conventional angiography. MR angiography is also less invasive and less expensive. Some researches have recommended use of 3-dimensional fourier transformation phase contrast magnetic resonance angiography.
Conclusions : For evaluating the arterial anatomy of living renal donors, helical C.T. angiography is superior to 3-D fourier transformation phase contrast MR angiography. Helical CT angiography is emerging as the investigation of choice for evaluating living renal donors. In addition to imaging vessels one can also study the parenchyma and the collecting system.
The study demonstrates a modest advantage of CT over MR angiography.
AC Gulanikar, PP Daily, NK Kilambi, et al (Univ of Mississipi Jackson)
Prospective Pretransplant Ultrasound Screening in 206 Patients for Acquired Renal Cysts and Renal Cell Carcinoma.
Transplantation 66: 1669-1672, 1998.
The fastest emerging population coming to dialysis comprises patients over 60 yrs of age. The long-term survival of patients in this category is generally poor. Hence there is little enthusiasm for screening all end-stage renal disease patients for acquired renal cystic disease and renal cell carcinoma.
The exception to the rule is patients who are healthy enough to be considered for renal transplantation.
A prevalence of renal cell carcinoma at 3.4% (much higher than the prevalence in the general population) is certainly high enough to warrant routine pretransplant screening. This is especially true in the light of the uncertainties regarding biologic activity of renal cell carcinoma in immunosuppressed hosts.