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This book will cover the modern use of ultrasound, computed tomography, magnetic resonance imaging, and radioisotopes in imaging the urinary tract. It will also offer an insight into new advancements in these modalities, including the fast developing field of functional imaging. This book offers information about a wide range of uroradiological topics, ranging from the use of magnetic resonance imaging or multislice computed tomography in urography to image-guided ablation of renal tumors. The...

Pulse Sequences For T2weighted Mr Urography

Static-fluid MR urograms are performed using heavily T2-weighted TSE sequence techniques, such as rapid acquisition with relaxation enhancement (RARE) or halfFourier acquisition single-shot turbo spin-echo (HASTE) (1,7,12,16,17). Initially, the RARE technique was employed to generate so-called nontomographic projection MR images of the urinary tract (1). Acquisition of a single-slice projection RARE image with a section thickness of 60 to 80 mm requires a short breath-hold of less than 10...

Principles Of T2weighted Mr Urography Staticfluid Mr Urography

T2-weighted MR urography simply provides water images of the urinary tract by acquisition of heavily T2-weighted turbo spin-echo (TSE) sequence techniques. The water we intend to visualize is the urine itself, which may be regarded as an intrinsic contrast medium.'' T2-weighted MR urography is well suited for imaging of obstructive urinary tract disorders, because the large amount of static fluid generates a good SNR (Fig. 1). Moreover, T2-weighted MR urography offers a diagnostic tool that is...

Results

Antegrade ureteral stenting is successful in 88 to 96 of cases, and more than 80 of obstructed ureters can be primarily stented without the need for prior nephrost-omy (89,90,92). Failure of placement is usually related to marked ureteral angulation or encasement by tumor or fibrosis. Technical failures can be minimized by placing the nephrostomy in a favorable calyx so as to provide the best vector for stent advancement, using transrenal sheaths as a buttress and using appropriately stiff...

Choosing the Correct Length of Ureteral Stent

A ureteral stent of the correct length will ensure patient comfort, trouble-free drainage and prevent irritative voiding symptoms. Ureteral stents are available in lengths ranging from 20 to 28 cm (a further range of shorter stents are also available for renal transplant patients) a specific length has to be chosen for each patient. Multilength or flexible-length ureteral stents are also available. They are made of a softer polymer that allows the pigtail to unfurl to the proper length, but...

Technique

Double Pigtailnephroureteral Stent

Ureteral stents can be inserted through a PCN tract or retrograde through the urethra or a urinary conduit. In difficult cases, a combined approach may be required. Successfully deployed ureteral stents allow for urine drainage and diversion without the inconvenience of a drainage bag. Percutaneous antegrade stent insertion is performed when retrograde insertion fails or is not possible. Antegrade ureteral stenting requires percutaneous access to the collecting system, preferably through an...

Info

BReconstructed slice thickness original slice thickness is twice as high with 50 overlap. Minimum calculated acquisition time without considering duration of individual respiratory compensation. Abbreviations', a, flip angle FOV, field of view GRE, gradient-echo MR, magnetic resonance NSA, number of signals averaged RFOV, rectangular field of view SENSE, sensitivity encoding TE, echo time TR, repetition time. bReconstructed slice thickness original slice thickness is twice as high with 50...

Mru For Non Dilated Duplex Sysyem

Figure 9 A nine-month-old girl with a left duplex kidney with upper pole ureterocele. (A) A coronal T2-weighted image shows a duplicated left collecting system with severe upper pole pelvocaliectasis and mildly dilated lower pole calyces. Portions of the left upper pole megaureter are visible in the pelvis (u). (B) A more anterior coronal T2-weighted image shows the markedly dilated left upper pole, multiple segments of the left upper pole megaureter, and a large left ureterocele in the bladder...

Is The Bosniak Classification Useful

It was established by Aronson et al., in a small study in 1991, that the Bosniak classification system was a useful management tool (25). In an investigation of 16 proven lesions, they found that all Category II lesions were benign and all Category IV lesions were malignant. Of the seven indeterminate cystic lesions in Category III, four (57 ) were malignant. There were a few subsequent series that retrospectively investigated the utility of this system and yielded varying results. A report by...

References

Warshauer DM, McCarthy SM, Street L, et al. Detection of renal masses sensitivities and specificities of excretory urography linear tomography, US, and CT. Radiology 1988 169 363-365. 2. Jamis-Dow CA, Choyke PL, Jennings SB, et al. Small (< 3-cm) renal masses detection with CT versus US and pathologic correlation. Radiology 1996 198 785-788. 3. Smith RC, Verga M, McCarthy S, Rosenfield AT. Diagnosis of acute flank pain value of unenhanced CT. Am J Roentgenol 1996 166 97-101. 4. Levine JA,...

Sentinel Node Localization

The concept of the sentinel node is one that is becoming accepted as being valuable in several groups of cancers. The hypothesis is that lymphatic drainage of tumors occurs in an orderly manner. The first node draining any lymphatic pathway is regarded as the sentinel node, in that any tumor dissemination along this pathway will occur via this node. Therefore, if this node is not involved with metastatic tumor, then nodes more distal to the tumor along this pathway will not be involved. For...

Approaches To

For a CT examination to allow for comprehensive urinary tract imaging, it must be able to adequately detect urinary tract calculi, renal masses, and renal collecting system, bladder, and ureteral abnormalities. Given the already widely acknowledged ability of CT to visualize renal masses and urolithiasis, recent modifications in CT technique have centered around the creation of a protocol allowing for detailed evaluation of the renal collecting systems, ureters, and bladder. There are several...

Radiation

The biggest potential problem with CTU performed using excretory-phase axial image acquisition is the incremental radiation that patients receive with multiphase CT. The amount of radiation to which patients are exposed is directly related to the mA and kVp, as well as to the number of phases acquired. Radiation dose can be estimated in a variety of ways. The amount of radiation emitted from the scanner during image acquisition that is absorbed by the patient can be calculated previously in rad...

RF Ablation

RF ablation is the most widely applied and thoroughly studied of the ablation technologies. The potential for local tumor destruction by RF was first appreciated when McGahan et al. published a paper detailing their work with in vivo porcine liver ablation using a rudimentary RF applicator based on the Bovie electrocautery system (45). Subsequently, there have been rapid improvements in the technology and it is now in widespread clinical use for the ablation of hepatic malignancies. In 1997,...

Y

Figure 10 Renal sinus replacement lipomatosis with renal stones. Unenhanced CT scan reveals calculi in the renal pelvis with associated renal parenchymal loss, increased amount of renal sinus fat, and renal sinus fat stranding. Abbreviation CT, computed tomography. Figure 11 Bilateral xanthogranulomatous pyelonephritis. (A) Unenhanced CT scan demonstrates large branching calculi in the renal pelvis bilaterally. (B) Enhanced CT scan demonstrates hydronephrotic-appearing areas of decreased...

Upper Tract Transitional Cell Carcinoma

Transitional cell carcinomas have a variety of CT urographic manifestations. They can appear as large masses that compress, distort, and obstruct the renal collecting system or ureteral lumen, thereby producing proximal renal collecting system or ureteral dilatation (Fig. 3). When these cancers are located in the intrarenal collecting system, the axial CT images can also be utilized to determine whether there has been renal parenchymal invasion (a feature of these tumors that affects their...

Image Interpretation And 3d Volumerendering

CT and MRI images are reviewed to evaluate each patient for a number of important features, including renal lesion size, lesion location, the number of renal arteries and veins, the presence or absence of renal vein tumor and inferior vena caval (IVC) tumor extension (and the degree of extension), enlargement of local, regional, and distant lymph nodes, and the presence or absence of local or regional metastatic disease. Tumor size and the presence of renal vein and IVC tumor thrombus and...

Evolving Technologies In Imaging Of The Prostate Gland

The emergence of disease-targeted ablative therapies, such as cryosurgery, bra-chytherapy, high-intensity focused ultrasound, and intensity-modulated radiation therapy, has necessitated accurate pretreatment tumor localization and staging. These techniques also require a means by which to assess posttreatment tumor response. Although standard endorectal coil MRI provides excellent anatomic detail of the prostate, it is limited by decreased specificity with regards to tumor detection and...

Calcifications

Calcifications can be present in Category II or Category III cystic masses and are a source of uncertainty in assigning a classification to a cystic renal mass. In an analysis of calcifications associated with 81 cystic renal masses, Israel and Bosniak Figure 3 Bosniak Category II hyperdense cyst. (A) Homogeneously hyperdense mass measuring 60 HU without intravenous contrast. (B) After intravenous contrast the mass did not enhance (61 HU). Abbreviation HU, Hounsfield unit. Figure 3 Bosniak...

Transplant Artery Stenosis

String Pearls Fmd Images

Cadaveric transplant kidneys are joined to the recipient's external iliac artery via an end-to-side anastamosis. Living donor kidneys are joined to either the external iliac Figure 14 Contrast-enhanced MR angiogram showing bilateral severe RAS (arrows). Note the post-stenotic dilatation. Abbreviations MR, magnetic resonance RAS, renal artery stenosis. Source Courtesy of Joe Brookes, The Middlesex Hospital, London. Figure 14 Contrast-enhanced MR angiogram showing bilateral severe RAS (arrows)....

Nonidiosyncratic Reactions

Nonidiosyncratic reactions are a diverse group (2,14), ranging from mild symptoms that are typically considered a physiologic effect of contrast media rather than a reaction to severe, even life-threatening, states. Nonidiosyncratic contrast reactions are for the most part dose dependent they are less likely to occur and, if they do occur, are less likely to be severe when smaller doses of contrast material are employed. In general, nonidiosyncratic reactions occur less often and with less...

Idiosyncratic Reactions

Idiosyncratic reactions most often begin within 20 minutes of contrast media injection (2). Their occurrence is not related to the dose of contrast material administered. They can be produced by the intravascular injection of even tiny amounts (less than 5 mL) of contrast material. Although the manifestations of idiosyncratic reactions are identical to those seen in patients having true anaphylactic reactions, reactions to contrast material are not true allergic reactions in the vast majority...

Complications

The single most frequent complication of ureteral stenting is occlusion of the stent due to encrustation, which is an unpredictable phenomenon but which appears to correlate with the length of time that a stent has been left in place. About 68 of stents that are indwelling for nine weeks have been found to be obstructed with mucus and microcalculi when they are removed (115,116). In another series, El-Faqih et al. (117) found that in patients in whom stents were placed for treatment of urinary...

MRI Protocol for Planning NSS

Localizer images are obtained to plan the diagnostic sequences. Typically, fast T1-weighted images are acquired in three planes. Then, T1-weighted in-phase and out-of-phase images are obtained using a 2-D fast gradient echo sequence without fat saturation. With a slice thickness of 5 to 6 mm, only about 20 slices are needed to cover the kidneys in a single breath-hold. On a 1.5 Tesla system, the out-of-phase time to echo (TE) is approximately 2 msec and the in-phase TE is approximately Figure 2...

Mri

As with CT evaluations, the preoperative evaluation for NSS with MRI also includes both pre- and post-contrast examinations (35). As with most body MRI examinations, the precontrast T1- and T2-weighted images are obtained to evaluate anatomy, to identify abnormalities, and to begin to characterize any identified renal or adrenal lesions (Fig. 4). Following intravenous gadolinium administration, postcontrast gradient-echo T1-weighted sequences are performed in multiple phases to define the...

Electron Ejaculation

Endorectal Coil Medrad Pittsburgh

Due to its excellent soft tissue contrast and direct multiplanar capabilities, magnetic resonance imaging (MRI) is well suited for evaluation of the prostate gland. Currently, most prostate magnetic resonance (MR) examinations are performed for staging of biopsy-proven prostate malignancies. However, prostate MRI can also be used to assess response to tumor therapy, to evaluate Mullerian abnormalities, and to diagnose complications of prostatitis. Applications of MRI in management of prostate...

Focal Thickening Of Postero Lateral Bladder Wall

Urinary Bladder Wall Thickening Causes

Figure 10 Caliceal diverticulum. (A) Excretory-phase axial image demonstrates a urine-contrast level in a mass in the upper pole of the right kidney (arrow). This mass had uniform water attenuation on the precontrast images. Based upon these findings, a diagnosis of caliceal diverticulum can be made. (B) This large caliceal diverticulum is also easily seen on the coronal volume-rendered 3-D reconstruction (arrow). Bladder cancers may also produce small mural nodules. These can be detected by...

Ct Evaluation

Phleboliths Pelvic

Application of Unenhanced Helical CT to the Evaluation of Flank Pain Since Smith et al. first reported the use of unenhanced CT in the evaluation of patients with flank pain in 1995, CT has become the study of choice for the evaluation of suspected ureterolithiasis (5). The sensitivity of noncontrast helical CT detection of urinary calculi has been reported to range from 97 to 100 , with specificities between 92 and 100 (13-16). Stone size and location can be accurately defined. In addition to...

Management Recommendations

Category IIF characterization implies that the lesion in question is probably benign, but some uncertainty exists because of the complex features described above. Thus, Category IIF cysts should be followed to make sure that the lesion shows stability over time. The finding of two malignancies in 42 (5 ) followed-up renal cystic masses in Bosniak's series should not be cause for alarm. As previously stated, cystic renal cell carcinomas are much less aggressive tumors than solid malignant renal...

Xeg

Figure 8 Utricle in a 70-year-old man. (A) Axial and (B) coronal T2-weighted images demonstrate a midline, benign utricular cyst of high signal intensity (white arrow). Figure 8 Utricle in a 70-year-old man. (A) Axial and (B) coronal T2-weighted images demonstrate a midline, benign utricular cyst of high signal intensity (white arrow). diagnosed in childhood because of its association with hypospadias, cryptorchidism, and ipsilateral renal agenesis (69-71). Mullerian duct cysts arise from the...

CT Protocol for Planning NSS

Three-phase CT protocols are the state of the art for imaging the kidneys and provide all the information necessary to plan for NSS (Fig. 1) (9-11). Scans should be performed on a multidetector helical scanner, which allows for the efficient use of intravenous contrast and facilitates the creation of thin-slice datasets for smooth 2-D and 3-D reformations. Technical parameters, such as kVp and mAs, should be kept consistent across the scan phases. The first scan phase is a noncontrast CT of the...

Ureteroenteral Anastomotic Strictures

Anastomotic Stricture

Strictures at the anastomosis of the ureter to an ileal conduit urinary diversion or continent urinary pouch or conduit are almost always benign and reportedly occur in 4 to 30 of patients (149-151). One study that compared complications in the different forms of urinary diversion reported the incidence of ureteroenteric strictures in ileal conduits to be 6.5 , compared to 10.0 in the continent reservoir group and 13.6 in patients who underwent ureterosigmoidostomy (150). The predisposing...

Principles Of T1weighted Mr Urography Gadolinium Excretory Mr Urography

In the T1-weighted imaging approach in MR urography, the enhancement of the collecting system is based on the shortening of T1-relaxation time of the urine after renal excretion of an intravenously injected gadolinium agent (2,18). Unlike static-fluid MR urography, the feasibility of gadolinium-enhanced T1-weighted MR urography correlates with the renal function. Accordingly, the methodology of T1-weighted MR urography is similar to that of conventional urography and is therefore designated as...

Ultrasound Guidance for Partial Nephrectomy and Ablative Therapies

Renal Vein Mass

During intraoperative ultrasound, whether open or laparoscopic, dedicated intraoperative probes that yield high-resolution images are used (Fig. 16) (41). These Figure 10 Anatomic right renal artery and vein variants. (A) Two right renal artery origins are seen (arrowheads) along with an accessory right renal vein (arrow). (B) The main right renal vein is seen (arrow) along with an unusual branch of the vein (long thin arrow) that results in a third renal vein entering into the inferior vena...

Herbal Medicine For Uretrohydronephrosis

Endourologic Stone Removal

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...

Renal Calculi Upj

Figure 10 Large calculus in a patient with a UPJ obstruction. A A 2.5 cm spiculated calculus is seen in the right renal pelvis. There is also a smaller interpolar stone. B An IVU demonstrates marked right UPJ narrowing. Both the large size of the stone and the UPJ narrowing are contraindications for SWL and make PCNL the treatment of choice. Abbreviations IVU, intravenous urogram PCNL, percutaneous nephrostolithotomy SWL, shock wave lithotripsy UPJ, ureteropelvic junction. Figure 10 Large...

Ureteral Stricture Dilation

Urether Stricture Dilated

Iatrogenic causes predominate in the development of ureteral strictures. Gynecologic and general surgical procedures are widely considered to be common causes of uret-eral trauma and stricture formation, but endourologic procedures such as uretero-scopy or ureterolithotomy , which facilitate less invasive management of many conditions, may paradoxically cause ureteral injury 135-137 . A 1 to 11 incidence of stricture formation has been reported after upper tract endoscopy 138 . Selzman and...

Indications for PCNL

SWL relies on stone fragmentation and propulsion of the fragments into the urinary bladder by urine flow and peristalsis. PCNL is therefore indicated when calculus fragmentation and passage would be suboptimal, so that the patient would not be rendered stone-free. The indications for PCNL are listed in Table 1. As the size of stones increases to greater than 2 cm to 3 cm, the fragmentation efficiency with SWL decreases, necessitating multiple SWL attempts for complete breakup and, often,...

Compression Saline Hydration and Furosemide

There is also variation in use of a variety of other maneuvers designed to improve renal collecting system and ureteral distention and opacification. Because abdominal compression has long been successfully used during EU, a number of researchers have advocated its use during CTU 10,12,37-39 . During MDCTU, compression is often applied at the time of contrast material injection. Compression excretory-phase images are then obtained through the kidneys, followed by compression release and...

Functional Impact Of Renal Diseases

Renal perfusion and glomerular filtration GFR are major functional parameters, which are involved in many renal parenchymal diseases. Noninvasive and accurate measurement of renal perfusion could have a major impact in understanding physio-pathology of renovascular diseases and in their follow-up. GFR is used as an index of functioning renal mass, representing the sum of filtration rates in each functioning nephron. A decrease in GFR may be the earliest and only clinical sign of renal disease,...

Advances In Image Quality And Image Presentation

Calculus Kidneysinreal

Research in the field of US has been always aimed at obtaining high spatial resolution, good penetration of the US beam, and reduction of signal-to-noise ratio. This has been possible from basic research in the behavior of US in tissues, the physical principles underlying piezoelectric materials, and from progress in the construction and miniaturization of electronic components. The new developments include modern piezoelectric materials with lower characteristic acoustic impedance and greater...

Incidental Hyperdense Masses On Nonfocused Ct

Bifid Collecting System Kidney Image

Occasionally a patient is scanned for a nonurologic reason and an incidental renal lesion is detected that has all the characteristic features of a simple cyst, except that its attenuation is above water density. On contrast-enhanced CT examinations, both hypovascular solid renal masses and hyperdense cysts will appear less dense than the adjacent highly enhancing renal parenchyma. Comparison to other water-density structures, such as the gallbladder or urinary bladder, is a simple method to...

Technique of PCN

Left Renal Parlor Caulaus

A drainage catheter placed through a retrograde approach, usually cystoscopy, is the preferred method to provide renal drainage in all patients, because it avoids the complications inherent in a PCN. The percutaneous route should ideally be reserved for patients in whom retrograde attempts are either unsuccessful or not feasible 11 . Preprocedural evaluation in patients being considered for PCN includes assessing the risk for bleeding and procedure-related infection. The surgical and medical...

Pitfalls In Image Interpretation

Mild Diffuse Cystitis

Several problems can be encountered when performing and interpreting CT urograms. Knowledge of these potential pitfalls is important so that studies can be performed with the optimal technique and erroneous interpretations minimized. Figure 13 Tiny bladder cancer. A 3 mm diameter bladder cancer projects into the contrast-containing lumen of the urinary bladder arrow , producing a small filling defect. This could not be seen on any of the 3-D reconstructed images. A variety of criteria must be...

Renal Infections

Urinary Collecting System

Acute Pyelonephritis and Renal Scarring Most upper urinary tract infections in children originate from bacterial contamination of the perineum and lower urinary tract by uropathogenic fecal flora. Although vesicoureteral reflux is the most widely described mechanism for upward transport of bacteria from the bladder to the renal collecting systems and kidneys, it is not invariably present in patients who develop ascending pyelonephritis. Other, as yet uncharacterized, mechanisms for upward...

CT Angiography

The advent of helical and now multichannel CT has allowed CT to become a powerful tool for imaging the vascular system. The technique involves a thinly collimated helical scan through the renal vascular pedicle during a venous injection of iodinated contrast media. With each scanner generation, resolution has improved. Now we can image isotropically and reformat in any plane while maintaining image quality. Improved speeds now allow scanning of the aorta from diaphragm to iliac bifurcation...

Technique for Percutaneous Urinary Interventions in Renal Transplants

The standard preprocedural preparations for a PCN are instituted. When planning a percutaneous puncture, it is important to avoid entry into the peritoneum by staying lateral to the lateral border of the transplant and the skin sutures. Transperitoneal punctures are more likely if an upper polar access is used and if the puncture is medial to the skin incision. Real-time ultrasound is useful in directing puncture into an anterolateral calyx with a minimal number of punctures. Although...

Postoperative Imaging

Recurrence After Radical Nephrectomy

At our institution, patients are seen four to six weeks after open partial nephrectomy for routine follow-up and have a physical examination, serum creatinine level check, and an excretory urogram 14 . Imaging with CT or ultrasound is performed earlier on any patient who has clinical signs or symptoms of abscess, hematoma, urinary leak, or fistula. Generally, a CT scan with intravenous contrast should be performed, and if a urine leak is of concern, delayed images should be obtained....

Background

The first radiograph of a urinary calculus was obtained by John McIntyre in 1896 within months of Roentgen's original report 6 . In the following century, many reports in the radiologic and urologic literature overestimated the ability of plain abdominal radiographs or KUBs to detect ureteral calculi 3 . In 1962, Herring examined the composition of 10,000 urinary calculi and found that approximately 90 of these contained calcium 7 . This report has been cited as evidence that 90 of ureteral...