Herbal Medicine For Uretrohydronephrosis

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Malrotation Urinary System

Figure 6 Excretory MR urography of a seven-year-old girl with a congenital single kidney.

(A) The coronal MIP from Tl-weighted GRE sequence shows complete gadoliniumenhancement of the nondilated urinary tract with abnormal configuration of the pelvicalices.

(B) The sagittal MIP demonstrates the malrotation of the pelvicalices with an anterior origin of the UPJ (arrow). Abbreviations: GRE, gradient-echo; MIP, maximum intensity projection; MR, magnetic resonance; UPJ, ureteropelvic junction.

This concept can be realized in a single session especially with the complementary use of T2-weighted and gadolinium-enhanced Tl-weighted imaging techniques.

In adult patients, variations of the urinary tract anatomy may not only be congenital but also acquired. For example, MR urography is able to demonstrate caliceal lesions associated with papillary necroses, caliceal diverticula, caliceal blunting in chronic pyelonephritis, and ureteric distortion caused by retroperitoneal fibrosis (Fig. 9), radiotherapy, or surgery (2,3,22).

Imaging of the upper urinary tract anatomy may also be important in patients who have undergone radical cystectomy and are referred for a postoperative follow-up. MR urography is useful for achieving a complete overview of the postoperative anatomy (Fig. 10). Assessment of the ureteral anastomoses is of special interest. Intravenous supplementation of a spasmolytic agent, such as butylscopolammonium bromide, has proved effective in suppressing motion artifacts resulting from peristalsis of a neobladder or an ileal conduit.

Ureterolithiasis

Figure 7 Seven-year-old girl with bifid pelvicalices on both sides. (A) The coronal MIP from excretory MR urography demonstrates a single ureter on the right and a duplex ureter on the left without dilatation. (B) The original source image of the T1-weighted 3-D dataset illustrates best that two separate ureteral orifices exist at the vesicoureteral junction on the left (arrows). Abbreviations: MIP, maximum intensity projection; MR, magnetic resonance.

Figure 7 Seven-year-old girl with bifid pelvicalices on both sides. (A) The coronal MIP from excretory MR urography demonstrates a single ureter on the right and a duplex ureter on the left without dilatation. (B) The original source image of the T1-weighted 3-D dataset illustrates best that two separate ureteral orifices exist at the vesicoureteral junction on the left (arrows). Abbreviations: MIP, maximum intensity projection; MR, magnetic resonance.

Furthermore, T2-weighted static-fluid MR urography has proved useful in the visualization of the complicated urinary tract anatomy in patients with spinal dysraphism (44).

Another application for combining T2- and T1-weighted MR urography is the assessment of parapelvic cysts, which may distort the pelvicaliceal anatomy and occasionally simulate hydronephrosis in ultrasonography. Static-fluid MR urography depicts the configuration and dimensions of cysts that may completely fill the renal sinus (Fig. 11). Excretory MR urography discloses the true pelvicaliceal anatomy because T1-weighted imaging allows distinguishing between nonenhan-cing cysts and gadolinium-enhancing pelvicalices, which are typically displaced and compressed (Fig. 11) (38).

Apart from these general anatomic issues, MR urography also provides accurate depiction of the urinary tract morphology in chronic urolithiasis, tumor diseases, transplant kidneys, and live kidney donors, as outlined in the following sections.

Urolithiasis

In patients presenting with acute stone colic, plain abdominal radiography plus ultrasonography or, alternatively, unenhanced multislice CT are imaging modalities

Figure 8 Nine-year-old girl with symptoms of urine dripping and enuresis. T2-weighted MR urography visualizes an ectopic ureter on the right side. The sagittal plane shows that the ureter (arrowheads) does not join the urinary bladder (arrow). After injection of furosemide, leakage of fluid into the vagina is detected (open arrow), indicating the presence of an ectopic ureteral orifice. The dysplastic right kidney is not seen on the MR urogram. Abbreviation: MR, magnetic resonance.

of choice, whereas MR urography plays only a minor role. One disadvantage of MRI in acute urolithiasis is the limited availability of in-bore times in emergency situations. Nevertheless, for those who already practice MR urography routinely, the detection of a pelvicaliceal calculus is not a rare finding (Fig. 11). Indeed, because urolithiasis is the major differential diagnosis in all urinary tract diseases, it is useful to know about the imaging features of stones in MRI.

Indirect signs of urolithiasis, such as uretrohydronephrosis and perinephric stranding, are readily seen on T2-weighted MR urograms. However, the main explanation for the limited value of MRI in urolithiasis is its poor capability for identifying small, calcified, soft-tissue structures, which is not a problem in CT. With MRI, we only have the chance to search for more or less typical filling defects. Most calculi present as round or branched signal voids (Figs. 11 and 12) inside the unenhanced or gadolinium-enhanced urine (2,5,7,20,24,29). However, such hypointense filling

Figure 9 In a male patient with suspected Ormond's disease, excretory MR urography visualizes both ureters over their entire length with medial displacement and distinct variations in caliber. A stricture causing impaired gadolinium flow is not seen. Abbreviation: MR, magnetic resonance.

defects are unspecific, and distinguishing a small stone from a blood clot, a polyp, or a surgical clip may occasionally cause diagnostic pitfalls. Moreover, it has to be pointed out that especially nonobstructing filling defects, including stones, may be invisible on MIP images and must be diagnosed exclusively by reading the source sections of the MR urographic pulse sequence (3). On source images, the tip of a papilla protruding into a calix must not be misinterpreted as a caliceal stone (Fig. 12). Calculi typically show an excentric location inside a calix, whereas the tip of a papilla usually has a central position (45).

Literature references reporting the sensitivity of MR urography in ureteral stone disease are already available (20,24,29). Between 90% and 94% of ureteral calculi are detected as filling defects on MR urograms (20,29). In a comparative study investigating ureterolithiasis on MR urography and unenhanced CT (29), the sensitivity of MR urography (93.8%) was equal to that obtained with CT (90.6%).

Figure 10 Excretory MR urography is performed in a male patient who underwent cystect-omy and nephroureterectomy on the left with orthotopic neobladder reconstruction. The gadolinium-enhanced Tl-weighted MIP accurately visualizes the postoperative urinary tract anatomy, including a nonstrictured uretero-ileal anastomosis (arrow). Abbreviations: MIP, maximum intensity projection; MR, magnetic resonance.

However, MR urography proved to be less exact than CT in determining the stone size (29). Corresponding data for nephrolithiasis are still unavailable, but it is very likely that MR urography will be inferior to unenhanced CT, especially in the detection of small caliceal calculi.

It would be justified if the question is raised as to whether there is any realistic application for MR urography in urolithiasis, apart from the limited value of MRI in acute stone disease. Especially in patients suffering from chronic or recurrent urolithiasis, MR urography is a potential alternative to CT for avoiding repeated radiation exposure (Figs. 11 and 13). In chronic nephrolithiasis resistant to treatment, MR urography provides detailed morphologic information about the complicated pelvicaliceal anatomy, which favors the formation of calculi and often leads to stone impaction (Fig. 13) (3,22). Unless there is an acute colic, the use of low-dose furosemide is actually not a problem in chronic stone disease. Prior to lithotripsy or endourologic stone removal, MR urography with multiplanar MIP images yields

Endourologic Stone Removal

Figure 11 (A) T2-weighted MR urography shows a large parapelvic cyst on the right side with compression of the pelvicalices. (B, C) The coronal and oblique MIP images from T1-weighted excretory MR urography disclose the true anatomic situation of the displaced pelvicalices on the right. The upper caliceal group is markedly dilated (arrowhead) because of infundibular obstruction (white arrow). Note also the filling defect inside the lower caliceal group of the left kidney (open arrow). (D) The corresponding source image of the 3-D GRE sequence reveals a 2 cm sized calculus (arrow) obstructing the lower infundibulum. The cyst on the right displays a characteristic low signal on the T1-weighted source image and is not directly seen on MIP images. Abbreviations: GRE, gradient-echo; MIP, maximum intensity projection; MR, magnetic resonance.

Figure 11 (A) T2-weighted MR urography shows a large parapelvic cyst on the right side with compression of the pelvicalices. (B, C) The coronal and oblique MIP images from T1-weighted excretory MR urography disclose the true anatomic situation of the displaced pelvicalices on the right. The upper caliceal group is markedly dilated (arrowhead) because of infundibular obstruction (white arrow). Note also the filling defect inside the lower caliceal group of the left kidney (open arrow). (D) The corresponding source image of the 3-D GRE sequence reveals a 2 cm sized calculus (arrow) obstructing the lower infundibulum. The cyst on the right displays a characteristic low signal on the T1-weighted source image and is not directly seen on MIP images. Abbreviations: GRE, gradient-echo; MIP, maximum intensity projection; MR, magnetic resonance.

a 3-D overview for determining the stone passage through a chronically affected collecting system (Fig. 13). Finally, T2-weighted MR urography can also be used for imaging of obstructive urolithiasis during pregnancy (13,46).

Transitional Cell Carcinoma

Many transitional cell carcinomas located in the pelvicalices or ureters can be detected noninvasively by standard contrast-enhanced CT or MRI without the need for a urographic phase. Nevertheless, the availability of thin urographic sections may

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