Tarek El-Diasty

Emphysematous pyelonephritis : A 15-year experience with 20 cases

OBJECTIVES To review our experience with emphysematous pyelonephritis over the past 15 years. METHODS Twenty patients with emphysematous pyelonephritis were reviewed regarding diagnosis, treatment, and outcome. RESULTS Women outnumbered men (75% versus 25%), and 80% of patients were diabetic. The left kidney was more frequently affected than the right one (60% versus 35%) and both kidneys were involved in 5%. Obstruction of the corresponding renoureteral unit was found in all the nondiabetic and in half of the diabetic patients. Diagnosis was confirmed by gas in the parenchyma or perinephric space by plain x-ray of the abdomen or computed tomography. Escherichia coli was the most common organism; it was found in 70% of urine cultures. A prompt attempt to control diabetes was made, and intravenous antibiotics were given. Nephrectomy was immediately performed after stabilization of the general condition of the patients. A total of 80% of patients survived the procedures. CONCLUSIONS For successful management of emphysematous pyelonephritis, appropriate medical treatment should be attempted but immediate nephrectomy should not be delayed.

Bladder tumour staging: comparison of diffusion- and T2-weighted MR imaging

The aim of this work was to evaluate the clinical feasibility of diffusion-weighted (DW) MRI in detection and staging of urinary bladder tumour and to compare DW MRI with the T2-weighted technique. One hundred and six patients with bladder tumour were prospectively included in our study. All patients were evaluated with MR imaging. We started with axial T2-weighted high resolution MR of the urinary bladder, then DW MRI. Two radiologists independently interpreted the MR images, and discrepancies were resolved by consensus. The accuracy of DW MRI in staging of bladder tumour was evaluated using the final histopathological findings. In DW imaging (DWI) staging accuracy was 63.6% and 69.6% in differentiating superficial from invasive tumours and organ-confined from non-organ-confined tumours, respectively. On a stage by a stage basis, DWI accuracy was 63.6% (21/33), 75.7% (25/33), 93.7% (30/32) and 87.5% (7/8) for stages T1, T2, T3 and T4, respectively. In the T2-weighted technique, the overall staging accuracy was only 39.6% and accuracy for differentiating superficial from invasive tumours and organ-confined from non-organ-confined tumours was 6.1% and 15.1%, respectively. DW is superior to T2-weighted MRI in staging of organ-confined tumours (≤T2) and both techniques are comparable in the evaluation of higher-stage tumours.

Bladder Cancer : Diagnosis with Diffusion-weighted MR Imaging in Patients with Gross Hematuria

PURPOSE To prospectively evaluate the usefulness of diffusion-weighted (DW) magnetic resonance (MR) imaging for the detection of bladder neoplasms in patients with gross hematuria of lower urinary tract origin. MATERIALS AND METHODS The study protocol received institutional ethical committee approval, and informed consent was obtained. Between April 2007 and March 2008, 130 consecutive patients with gross hematuria whose upper urinary tract had a normal appearance at ultrasonographic examination were prospectively enrolled. Mean age was 59.4 years (range, 45-75 years). All patients were evaluated by using T2-weighted high-spatial-resolution MR imaging of the urinary bladder, followed by DW MR imaging. Two radiologists independently interpreted the T2-weighted and DW images, and discrepancies were resolved by consensus. Agreement was evaluated by using the kappa statistic. All patients underwent conventional cystoscopy. With cystoscopy and the final histopathologic findings as the reference standards, a comparison with imaging findings was performed by using the McNemar test. RESULTS The consensus diagnostic performance of DW MR imaging for identification of bladder tumors was: sensitivity, 98.1% (104 of 106); specificity, 92.3% (24 of 26); PPV, 100% (104 of 104); negative predictive value, 92.3% (24 of 26); and accuracy, 97.0% (128 of 132). Two cases were falsely negative on T2-weighted MR images but were correctly diagnosed by using DW MR images. The agreement between DW MR imaging results and cystoscopic findings was excellent (kappa = 0.94) for identification of bladder neoplasm. DW MR imaging had a sensitivity and PPV of 98.5% (128 of 130) and 100% (128 of 128), respectively, for determining the cause of hematuria. CONCLUSION DW MR imaging is a highly reliable imaging approach for identification of bladder tumors in patients with gross hematuria.

Urological complications after living‐donor renal transplantation

Objective To determine the incidence and management of urological complications after 1200 consecutive live‐donor renal transplantations, all of which were carried out in one centre; the possible risk factors and the effect on patient and graft survival were also assessed.

Models and methods for analyzing DCE‐MRI: A review

PURPOSE To present a review of most commonly used techniques to analyze dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), discusses their strengths and weaknesses, and outlines recent clinical applications of findings from these approaches. METHODS DCE-MRI allows for noninvasive quantitative analysis of contrast agent (CA) transient in soft tissues. Thus, it is an important and well-established tool to reveal microvasculature and perfusion in various clinical applications. In the last three decades, a host of nonparametric and parametric models and methods have been developed in order to quantify the CAs perfusion into tissue and estimate perfusion-related parameters (indexes) from signal- or concentration-time curves. These indexes are widely used in various clinical applications for the detection, characterization, and therapy monitoring of different diseases. RESULTS Promising theoretical findings and experimental results for the reviewed models and techniques in a variety of clinical applications suggest that DCE-MRI is a clinically relevant imaging modality, which can be used for early diagnosis of different diseases, such as breast and prostate cancer, renal rejection, and liver tumors. CONCLUSIONS Both nonparametric and parametric approaches for DCE-MRI analysis possess the ability to quantify tissue perfusion.

Urethral Controlled Bladder Substitution: A Comparison between the Intussuscepted Nipple Valve and the Technique of Le Duc as Antireflux Procedures

A urethral controlled bladder substitute was constructed from a detubularized, double folded ileal segment in 40 male patients following cystoprostatectomy for bladder cancer. For reflux prevention patients were prospectively randomized to receive either an intussuscepted nipple valve or the ureters were implanted by the Le Duc mucosal trough technique. All patients had normal upper tracts preoperatively. Mean patient age, performance status and stage of cancer were comparable in both groups. Patients were evaluated 6 to 18 months postoperatively. In addition to history taking, assessment included excretory urography, ascending cystography and voiding cystourethrography. During the observation period all patients with nipple valves had normal radiographic appearance of the upper tracts without evidence of reflux. On the other hand, following the Le Duc procedure 12 of 38 renal units (31%) showed evidence of radiographic dilatation. Of the 12 units 11 had stenotic ureters and 1 had reflux. We conclude that nipple valves are more effective in reflux prevention and protection of the upper urinary tract in patients for whom an ileal neobladder is indicated.

Diffusion-Weighted MR Imaging in Diagnosis of Superficial and Invasive Urinary Bladder Carcinoma: A Preliminary Prospective Study

We conducted a prospective study to demonstrate the feasibility of using diffusionweighted (DW) magnetic resonance imaging (MRI) for the detection of urinary bladder carcinomas. Between January to June 2007, 43 patients with single bladder tumor were included in our study. Before taking a biopsy, DW MRI was obtained in the axial plane under free breathing scanning with a multisection, spin-echo type, single-shot echo planar sequence with a body coil. Moreover, the apparent diffusion coefficient (ADC) value was measured in a circular region of interest within the carcinoma, urine, normal bladder wall, prostate, and seminal vesicle. All carcinomas in the 43 patients were clearly shown as high signal intensity relative to the surrounding structure. The sensitivity and positive predictive values of DW MRI were 100% in terms of correctly detecting the carcinomas. The ADC value in the carcinoma (1.40 ± 0.51) was significantly lower compared with that of urine (3.50 ± 0.43) (p < 0.001), normal bladder wall (2.29 ± 0.78) (p < 0.001), peripheral zone of prostate (1.77 ± 0.44) (p < 0.05), transition zone of prostate (1.88 ± 0.54) (p < 0.05), and the seminal vesicle (2.12 ± 0.43) (p < 0.001). There was no statistical difference in ADC values between different histological subtypes. There was no overlap between the ADC values of the tumors and the urine, but there was no clear cutoff between the tumor and bladder wall, prostate, or seminal vesicles. Bladder carcinomas have significantly lower ADC when compared to surroundings. Clinical experience with this method is still preliminary and further studies are required.

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

AbstractDiuretic 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.

Appearance models for robust segmentation of pulmonary nodules in 3d LDCT chest images

To more accurately separate each pulmonary nodule from its background in a low dose computer tomography (LDCT) chest image, two new adaptive probability models of visual appearance of small 2D and large 3D pulmonary nodules are used to control evolution of deformable boundaries. The appearance prior is modeled with a translation and rotation invariant Markov-Gibbs random field of voxel intensities with pairwise interaction analytically identified from a set of training nodules. Appearance of the nodules and their background in a current multi-modal chest image is also represented with a marginal probability distribution of voxel intensities. The nodule appearance model is isolated from the mixed distribution using its close approximation with a linear combination of discrete Gaussians. Experiments with real LDCT chest images confirm high accuracy of the proposed approach.

Long-term functional and morphological effects of transcatheter arterial embolization of traumatic renal vascular injury

To assess the long‐term morphological and functional outcome of superselective transarterial embolization (TAE) for treating traumatic renal vascular injury.