| Objective: 1. To evaluate magnetic resonance urography (MRU) technique and observe the anatomy and variations of the urinary tract.2. To investigate the value of clinical applications of MRU in the diagnosis of diseases of urinary system, especially urinary tract obstruction.Materials and Methods: 1. 110 patients were simultaneously examined with a 2D heavily T2-weighted thick-slab turbo spin-echo and thin-slice half-Fourier acquisition single-shot turbo spin-echo. Post procedure processing was performed with a maximum intensity projection (MIP) algorithm. The results of two kinds of imaging sequence were evaluated separately and independently for the sort and level, and generally compared and judged.2. The normal anatomy and congenital anomalies of urinary system were classified and the percentage of each variation was calculated. MRU of 6 sorts of 20 cases of congenital anomalies were analyzed, including ureteropelvic junction obstruction 11 cases, renal pelvis and ureteral duplication 3 cases, solitary kidney 2 cases, retrocaval ureter 2 cases and dysplasia kidney 2 cases (1 case with ectopy orifice of ureter of the same side).3. MRU of 73 cases of diseases of urinary system (urinary tract obstruction, without obstruction and others) were classified and analyzed, including ureteral calculus 22 cases, ureteral inflammatory stenosis 12 cases, primary carcinoma of ureter 10 cases, metastatic ureteral carcinoma 5 cases, postoperative cicatrization 4 cases, pelvic endometriosis 2 cases, retroperitoneal fibrosis 2 cases, pelvic lipomatosis 1 cases, kidney stone 9 cases, renal tuberculosis 7 cases, renal pelvic carcinoma 3 cases, carcinoma of the urinary bladder 4 cases, simple cyst of kidney 15cases, multicystic kidney 3 cases, acquired renal cystic 3 cases, urinary tract non-obstruction dilatation 2 cases. To evaluate and sum up the MRU manifestations and signs of the diseases.Results: 1. In the diagnosis of the site and extent of urinary tract obstruction, there is no difference between the two methods of MRU scan (heavily T2-weighted thick-slab TSE and thin-slice HASTE), with the same accuracy of 100%. About the local orientation of the cause of obstruction, TSE obviously had more uncertainty. In the detection of stones, the sensitivity of TSE and HASTE is respectively 68.8% and 78.6%. The shape of urinary tract was very clearly showed in TSE, and the artifact of around organs was restrained. HASTE 3DMRU and its original images can offer more general imaging information. The combined use of both thick-slab TSE and thin-slice HASTE sequences will ensure better confidence of in the qualitative diagnosis of diseases.2. 17 cases MRU of normal urinary tract all can reveal renal parenchyma and plentiful urinary bladder, and 10 cases MRU of normal ureter manifest local inadequate or mild irregular and circuitous. 20 cases of congenital anomalies of urinary system were proved in MRU. UPJ obstruction (n=12): MRU can show that the shape of obstruction end was infundibuliform and demonstrate the obviously dilated collecting system. Renal pelvis and ureteral duplication (n=3): MRU can clearly display the panorama of abnormality, including one case of perfectibility duplex ureter with the dilated upper urinary tract, and 2 cases of non-perfectibility duplex ureter. Solitary kidney (n=2): MRU can show renal and ureter of the right side was absence (1 case with UPJ obstruction of the left side). Retrocaval ureter (n=2): all were manifested low-twist types. MRU can display urinary tract obstruction of the right side and abnormal 'S' shape track of upside ureter. Dysplasia kidney (n=2), including one case with ectopy orifice of ureter of the same side in vagina. MRU can show the loss of volume of affected renal, thin renal parenchyma and scanty number of calices.3. There were 58 cases of benign and malignant diseases of urinary tract obstruction except the obstruction of congenital anomalies, which the level of obstruction was mostly located at the middle or distal ureter and the degree ofobstruction was mostly from mild to moderate. (1) Benign urinary tract obstruction: Ureteral calculus (n=22): MRU can easily show the larger calculi, and then manifested hypointensity filling defect, 'Cupule sign' and 'soft-tissue rim sign'. In comparison with the results of KUB+IVU, 18 cases of MRU difficultly depicted the calculi less than 5mm in diameter. But in terms of evaluating the image and obstruction of urinary tract, MRU had higher specificity and accuracy than IVU. Ureteral inflammatory stenosis (n=12): 7 cases of ureteral tuberculosis were depicted irregular 'string of beads' like stenosis in MRU. Postoperative cicatrisation (n=4): Medical history was explicit, and MRU showed oval intercepted obstruction. Pelvic endometriosis (n=2): MRU clearly demonstrated irregular cystic hyperintensity or patchy heterogeneous intensity around the end of obstruction. Retroperitoneal fibrosis (n=2): Bilateral ureter manifested taper of benign stenosis and midline shift at the same level. Pelvic lipomatosis (n=l): The distal of bilateral ureter was depicted intercepted obstruction at the same level and bilateral urinary tract was showed symmetrically dilation and hydronephrosis. (2) Malignant urinary tract obstruction: Primary carcinoma of ureter (n=10): The shape of end of obstruction can be displayed 'beak sign', filling defect in cavity or parenchyma mass around in MRU. Metastatic ureteral carcinoma (n=5): One case is multiple. MRU displayed intercepted or 'tail sign' stenosis. (3) Urinary tract diseases without obstruction: Kidney stone (n=9): Most of them were combined with urinary tract dilation, and original images of MRU were in favor of detecting the deposit of hypointensity calculi. Renal tuberculosis (n=6): The manifestation tuberculo-purulent kidneys were the formation of multiple lobulated varied-size cyst and cavitation in MRU. Renal pelvic carcinoma (n=3), Carcinoma of the urinary bladder (n=4): MRU displayed hypointensity filling defect and original images can help to sketch the shape of tumor. Simple cyst of kidney (n=15), Multicystic kidney (n=3): The latter was shown alveolate hyperintensity of both kidneys and part of them with nonhomogeneous intensity. Acquired renal cystic (n=3): MRU showed dense arrange hypointensity tiny cyst of renal cortex. Urinary tract non-obstruction dilatation (n=2): Bilateral urinary tract symmetric dilatation and non-stenosis was shown by MRU. One case of prostatic hypertrophy manifested the sign of neurogenic bladder. (4) Others: Urinoma (n=2): MRU depicted abnormalhyperintensity fluid region around kidney. Obstructive extrarenal pelvic (n=2): The dilated renal pelvic had an abnormal position and cystic hyperintensity around renal gate and upper ureter was manifested.Conclusions: 1. MRU as a reliable, noninvasive, safe method of urinary tract imaging technique can be 3D imaging and simultaneous detect urinary tract and renal parenchyma. The combined use of both 2D thick-slab TSE and thin-slice HASTE sequences will ensure better confidence of diagnosis.2. The panorama of urinary system image can be wholly clearly visualized by MRU, which be helpful in demonstrating the anatomy and variations. Of the 110 patients examined, all of variations are at 18.2%.3. For the diseases of urinary tract obstruction, the applications of MRU is very valuable. A diagnostic accuracy of the level and extent of obstruction was 100% and diagnostic rating of the obstructive etiology was 83%. In the general evaluation and diagnosis of ureteral calculus and secondary urinary tract changes, MRU was superior to KUB+IVU. It is clinically valuable of offering information to detect urinary tract diseases without obstruction and evaluate some especial signs.4. MRU has the superiority over other urinary tract imaging methods, which can replace traumatic examinations and become the first choice for the children and the patients who cannot bear intravenous urography. |
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