Julia R. Fielding

Spiral Computerized Tomography in the Evaluation of Acute Flank Pain: A Replacement for Excretory Urography

PURPOSEnWe determined the value of noncontrast enhanced spiral computerized tomography (CT) in the evaluation of suspected renal colic.nnnMATERIALS AND METHODSnThin section (5 mm.) noncontrast enhanced CT was used to evaluate 100 patients presenting to the emergency room with flank pain. The 55 patients with ureteral obstruction were followed at the urology outpatient clinic and by telephone interview, while 45 without ureteral obstruction were followed by telephone interview and chart review. Sensitivity, specificity, and positive and negative predictive values for CT were determined, with passage, retrieval or identification of a stone on a retrograde study considered the gold standard for diagnosis.nnnRESULTSnA total of 89 patients had adequate clinical followup to assess outcome accurately. Of 55 patients with ureteral obstruction on CT 11 underwent endoscopic stone removal, while 44 were treated conservatively with stone passage documented in 39. Of the 45 patients without ureteral stones identified 38 did not pass calculi and CT provided a definite diagnosis in 14. There was 1 false-negative study. The results yielded 98% sensitivity, 100% specificity, and 100% positive and 97% negative predictive values.nnnCONCLUSIONSnNoncontrast enhanced spiral CT was accurate and reliable in detecting obstructing ureteral calculi in patients with flank pain.

Etiology Of Spontaneous Perirenal Hemorrhage: A Meta-Analysis

PURPOSEnWe determine the most common etiology of spontaneous perirenal hemorrhage.nnnMATERIALS AND METHODSnA MEDLINE search of the English language literature from 1985 to 1999 revealed 47 publications and 165 cases of spontaneous renal hemorrhage meeting our study entry criteria. These criteria were presentation of raw data including imaging modality, pathological confirmation (123 cases) or long-term (greater than 2 years) (42) imaging and/or clinical followup and no history of recent trauma, anticoagulant use, dialysis or renal transplant. Meta-analysis was performed using analysis of counts derived from contingency tables and pooled and stratified analysis.nnnRESULTSnHemorrhage was identified by ultrasound in 56 of 100 cases (56%) and by computerized tomography (CT) in all 135 cases assessed (100%). Etiology was correctly identified with an overall sensitivity and specificity of 0.11 and 0.33 for ultrasound and 0.57 and 0.82 for CT. Angiography in 81 cases revealed active bleeding in 11. The most common etiology of spontaneous renal hemorrhage was benign or malignant neoplasm (101 cases, 61%) with angiomyolipoma being predominant (48) followed closely by renal cell carcinoma (43). Vascular disease was the next most common offender (28 cases, 17%) with polyarteritis nodosa occurring most frequently (20).nnnCONCLUSIONSnThe most common cause of spontaneous perirenal hemorrhage is renal neoplasm and approximately 50% of such neoplasms are malignant. CT is the method of choice for evaluation of perirenal hemorrhage, although its sensitivity for detection of underlying etiology is only moderate.

Ct and Ultrasound Features of Metanephric Adenoma in Adults with Pathologic Correlation

PURPOSEnThe purpose of this work was to correlate the CT, ultrasound, and pathologic features of metanephric adenoma, a rare benign renal tumor in adults.nnnMETHODnRetrospective review of medical records (1990-1997) revealed three adult female patients who had both preoperative imaging and nephrectomy with pathologic diagnosis of metanephric adenoma performed at our institution. CT (n = 3) and ultrasound (n = 2) features were reviewed in consensus by two radiologists and correlated with pathologic findings.nnnRESULTSnIn all three cases, the metanephric adenoma was of increased attenuation relative to adjacent renal parenchyma on unenhanced CT scans. No septa or calcifications were seen. Ultrasound images showed both tumors to be hyperechoic with enhanced through-transmission.nnnCONCLUSIONnThe CT and ultrasound findings correlate with the pathologic features of a high nuclear-to-cytoplasmic ratio and psammomatous calcifications. In the adult population, it is unlikely that metanephric adenoma can be prospectively differentiated from renal cell carcinoma based on imaging features.

TUMOR DETECTION BY VIRTUAL CYSTOSCOPY WITH COLOR MAPPING OF BLADDER WALL THICKNESS

PURPOSEnWe determine the value of color mapping of bladder wall thickness for detection of tumor as a component of virtual cystoscopy.nnnMATERIALS AND METHODSnA total of 31 subjects with hematuria and/or a history of bladder tumor underwent helical computerized tomography of the pelvis after distention of the bladder with air. Three-dimensional (D) models were constructed, and thickness of the wall was color mapped according to a fixed and validated mm. scale. Axial source images and 3-D models were reviewed and graded for the presence of wall thickening. A comparison was made with findings on conventional cystoscopy in 31 patients and pathological specimen in 13.nnnRESULTSnCompared with conventional cystoscopy, the analysis of axial image yielded a sensitivity of 0.80, specificity 0.90, positive predictive value 0.80 and negative predictive value 0.90 for the presence of tumor. Examination of color mapped 3-D renderings resulted in 0.83, 0.36, 0.42 and 0.71, respectively.nnnCONCLUSIONSnThin axial computerized tomography of the air distended bladder shows promise as a potential screening tool for bladder cancer. The low specificity of color mapped 3-D renderings makes the technique inappropriate for screening. It may valuable for guiding urologists to additional suspicious sites in a patient with a known tumor.

Spiral CT in the evaluation of flank pain: overall accuracy and feature analysis.

PURPOSEnOur goal was to assess test reliability and identify those features that have the strongest positive and negative predictive values in the diagnosis of renal colic using spiral CT.nnnMETHODnFifty non-contrast-enhanced CT scans (5 mm slice thickness) obtained in patients presenting with flank pain were reviewed by three radiologists blinded to the final diagnoses. The sensitivity, specificity, and positive and negative predictive values for nine pertinent findings were determined as compared to clinical follow-up.nnnRESULTSnTwenty-nine cases had findings of ureteral obstruction. Findings with the strongest positive predictive values (> 0.90) were ureteral stone, hydronephrosis, hydroureter, periureteral stranding, and ureterovesical junction edema. Findings with the strongest negative predictive values (> 0.89) were absence of hydronephrosis and hydroureter. The areas under the receiver operating curves for Readers 1, 2, and 3 were 0.970 +/- 0.030, 0.942 +/- 0.036, and 0.982 +/- 0.020.nnnCONCLUSIONnAbsence of hydroureter and hydronephrosis on spiral CT images should prompt a search for a diagnosis other than an obstructing ureteral stone.

Virtual CT cystoscopy: color mapping of bladder wall thickness.

RATIONALE AND OBJECTIVESnTo improve the conspicuity of bladder tumors in a virtual environment, we developed an algorithm for color mapping the thickness of the bladder wall. The purpose of this study was to demonstrate the feasibility of this algorithm as a component of virtual CT cystoscopy.nnnMETHODSnFive subjects with a history of superficial transitional-cell carcinoma of the bladder underwent helical CT scanning after insufflation of the bladder with air. Source images were transformed into three-dimensional models, and the thickness of the bladder wall was demarcated by using a new computer algorithm and a fixed color scale. Results were compared with those obtained by conventional cystoscopy.nnnRESULTSnThree tumors, one site of benign wall thickening, and normal wall thickness were correctly identified by using axial source images and virtual cystoscopy with color mapping.nnnCONCLUSIONSnColor mapping of bladder wall thickness is feasible and demonstrates both normal and thickened urothelium. Its value in identification of small or sessile tumors will require further trials.

Original smooth receiver operating characteristic curve estimation from continuous data: Statistical methods for analyzing the predictive value of spiral CT of ureteral stones

RATIONALE AND OBJECTIVESnDiagnostic studies such as spiral computed tomography (CT) in patients with obstructing ureteral calculi often necessitate the analysis of continuous test data (e.g., stone sizes). The accuracy of a test can be summarized by using a receiver operating characteristic (ROC) curve. The authors developed and compared three methods for constructing a smooth ROC curve from continuous diagnostic data.nnnMATERIALS AND METHODSnNonparametric, semiparametric, and parametric smooth ROC curve analyses were applied to data from 100 unenhanced spiral CT scans of patients with proved obstructing ureteral stones. Accuracy in using stone size to predict the need for intervention was evaluated by means of these methods. Characteristics and summary measures of the resulting ROC curves were estimated.nnnRESULTSnAll methods fit the data well. The nonparametric method followed the details of the empiric data. The semiparametric and parametric methods yielded similar estimates of the ROC curve parameters. Areas under the ROC curves were 0.807, 0.821, and 0.814 for nonparametric, semiparametric, and parametric methods, respectively, in comparison with 0.811 for the empiric method.nnnCONCLUSIONnThe parametric method is preferred for constructing a smooth ROC curve with available stone-size data derived from spiral CT. The analyses confirm the predictive value of stone size in determining the need for intervention.

Bayesian Regression Methodology for Estimating a Receiver Operating Characteristic Curve with Two Radiologic Applications: Prostate Biopsy and Spiral CT of Ureteral Stones☆

RATIONALE AND OBJECTIVESnThe authors evaluated two Bayesian regression models for receiver operating characteristic (ROC) curve analysis of continuous diagnostic outcome data with covariates.nnnMATERIALS AND METHODSnFull and partial Bayesian regression models were applied to data from two studies (n = 180 and 100, respectively): (a) The diagnostic value of prostate-specific antigen (PSA) levels (outcome variable) for predicting disease after radical prostatectomy (gold standard) was evaluated for three risk groups (covariates) based on Gleason scores. (b) Spiral computed tomography was performed on patients with proved obstructing ureteral stones. The predictive value of stone size (outcome) was evaluated along with two treatment options (gold standard), as well as stone location (in or not in the ureterovesical junction [UVJ]) and patient age (covariates). Summary ROC measures were reported, and various prior distributions of the regression coefficients were investigated.nnnRESULTSn(a) In the PSA example, the ROC areas under the full model were 0.667, 0.769, and 0.703, respectively, for the low-, intermediate-, and high-risk groups. Under the partial model, the area beneath the ROC curve was 0.706. (b) The ROC areas for patients with ureteral stones in the UVJ decreased dramatically with age but otherwise were close to that under the partial model (ie, 0.774). The prior distribution had greater influence in the second example.nnnCONCLUSIONnThe diagnostic tests were accurate in both examples. PSA levels were most accurate for staging prostate cancer among intermediate-risk patients. Stone size was predictive of treatment option for all patients other than those 40 years or older and with a stone in the UVJ.

Double Cervix and Vagina With Septate Uterus: An Uncommon Müllerian Malformation

BACKGROUND The case of an unusual müllerian anomaly is described. CASE A nulligravida was found to have a septate uterus with double cervix and a vagina with partial longitudinal vaginal septum. The anomaly presented symptomatically, was suggested by clinical examination, and confirmed by magnetic resonance imaging and intraoperative visualization. Visualization of the anomaly was enhanced by magnetic resonance-based three-dimensional reconstruction techniques. CONCLUSION Description of double cervix and vagina in the setting of an anatomically normal or simple septate uterus is uncommon. This anomaly is inconsistent with the generally accepted understanding of müllerian development but fits with an alternative hypothesis. Magnetic resonance imaging and magnetic resonance-based three-dimensional reconstruction was useful in aiding visualiza tion of the anomaly.

OPEN-CONFIGURATION MR IMAGING, INTERVENTION, AND SURGERY OF THE URINARY TRACT

The open-configuration MR imaging system provides new applications both in diagnosis and in therapy of conditions in the urinary tract. In addition to conventional imaging, the open configuration permits MR imaging of patients in many positions. This has already been shown to be useful in imaging the pelvis during voiding, where a sitting position allows urodynamic evaluation. The lithotomy position can be used for imaging the prostate, which also permits procedural access. The ultimate purpose of the interventional MR imaging suite is to integrate therapeutic tools and techniques with MR imaging. From surgical planning through specialized imaging systems with minimally invasive surgical applications, new methods are being developed and implemented. This new field of image-guided therapy will require extensive clinical development and evaluation for applications in the urinary tract. This will require a large concentrated interdisciplinary effort of surgeons, radiologists, computer scientists, engineers, and physicists. Successful integration of basic research and clinical work will result in a number of cutting-edge technologies with direct clinical application in the urinary tract. Initial projects have included biopsies, endoscopies, and real-time procedural control of high-temperature and cryogenic ablations. It is anticipated that the current surge in image-guided interventions will motivate even more research activity in this field, and will ultimately define the role of MR imaging guidance in urologic intervention and surgery.