Unenhanced MDCT in Patients with Suspected Urinary Stone Disease: Do Coronal Reformations Improve Diagnostic Performance?

Urothelial-phase thin-section MDCT of the bladder in patients with hematuria: added value of multiplanar reformatted images

PURPOSE

To evaluate the diagnostic performance of MDCT with axial images and multiplanar reformatted (MPR) images from the urothelial phase of the bladder in patients with hematuria using cystoscopy as the reference standard.

MATERIALS AND METHODS

Our IRB for human investigation approved this study, and informed consent was waived. We included 192 patients (121 men, 71 women; age range 17-90 years; mean age ± SD: 60 ± 14 years) who underwent contrast-enhanced MDCT (scan delay: 70 s; section thickness: 2 mm) and conventional cystoscopy examination for painless gross hematuria or recurrent microscopic hematuria. Two radiologists in consensus interpreted the images for the presence or absence of bladder lesions. Using the kappa statistic, the patient-based agreement was determined between the CT and cystoscopic findings. We compared the diagnostic performance of axial images to those with coronal and sagittal reformations to detect bladder lesions.

RESULTS

MDCT showed excellent agreement between cystoscopy-axial scans (κ = 0.896) and axial with reformatted images (κ = 0.948). The sensitivity, specificity, and accuracy of MDCT were 94%, 96%, and 95% in the axial scans and 98%, 97%, and 97% in the axial with reformatted images, respectively. All statistical parameters of diagnostic performance were similar between the axial and the reformatted images (p > .05).

CONCLUSION

Axial MDCT imaging demonstrates high diagnostic performance in detecting bladder lesions, but additional reformatted images can improve diagnostic accuracy.

Predicting the effectiveness of extracorporeal shock wave lithotripsy on urinary tract stones. Risk groups for accurate retreatment

INTRODUCTION

Extracorporeal shock wave lithotripsy (ESWL) is a non-invasive, safe and effective treatment for urinary tract lithiasis. Its effectiveness varies depending on the location and size of the stones as well as other factors; several sessions are occasionally required. The objective is to attempt to predict its success or failure, when the influential variables are known beforehand.

MATERIAL AND METHODS

We analysed 211 patients who had had previous CT scans and were treated with ESWL between 2010 and 2014. The influential variables in requiring retreatment were studied using binary logistic regression models (univariate and multivariate analysis): maximum density, maximum diameter, area, location, disintegration and distance from the adipose panniculus. With the influential variables, a risk model was designed by assessing all possible combinations with logistic regression (version 20.0 IBM SPSS).

RESULTS

The independent influential variables on the need for retreatment are: maximum density >864HU, maximum diameter >7.5mm and pyelocaliceal location. Using these variables, the best model includes 3risk groups with a probability of requiring significantly different retreatment: group 1-low risk (0 variables) with 20.2%; group 2-intermediate risk (1-2 variables) with 49.2%; and group 3-high risk (3 variables) with 62.5%.

CONCLUSIONS

The density, maximum diameter and pyelocaliceal location of the stones are determinant factors in terms of the effectiveness of treatment with ESWL. Using these variables, which can be obtained in advance of deciding on a treatment, the designed risk model provides a precise approach in choosing the most appropriate treatment for each particular case.

Renal stones on portal venous phase contrast-enhanced CT: does intravenous contrast interfere with detection?

PURPOSE

To determine the sensitivity of portal venous phase contrast-enhanced CT for the detection of renal stones.

METHODS

This retrospective study included 97 CT examinations of the abdomen without and with intravenous contrast, including 85 (87.6%) examinations with at least one renal stone on the "gold standard" noncontrast images, as scored by a single radiologist. Three other radiologists each independently reviewed only the contrast-enhanced images from all 97 examinations and recorded all renal stones. Reviewer sensitivity for stones was categorized by stone diameter. Reviewer sensitivity and specificity for stone disease were also calculated on a per-kidney basis.

RESULTS

The 97 cases included a total of 238 stones ≥1 mm, with a mean (±SD) of 1.2 ± 1.9 stones per kidney and a stone diameter of 3.5 ± 3.0 mm. Pooling data for the three reviewers, sensitivity for all stones was 81%; sensitivity for stones ≥2, ≥3, ≥4, and ≥5 mm was 88%, 95%, 99%, and 98%, respectively. Sensitivity for stone disease on a per-kidney basis was 94% when considering all stones; when considering only stones ≥2, ≥3, and ≥4 mm, sensitivity was 96%, 99%, and 100%, respectively. Specificity for stone disease on a per-kidney basis was 98% overall, 99% when considering only stones ≥2 mm, and 100% when considering only stones ≥3 mm.

CONCLUSION

Contrast-enhanced CT is highly sensitive for the detection of renal stones ≥3 mm in diameter and less sensitive for smaller stones. In cases where the clinical diagnosis is uncertain and performance of a CT examination is being contemplated, intravenous contrast utilization would allow assessment for stone disease while also optimizing evaluation for other conditions.

Unenhanced MDCT in suspected urolithiasis: improved stone detection and density measurements using coronal maximum-intensity-projection images

OBJECTIVE

The purpose of this study was to determine whether coronal maximum-intensity-projection (MIP) reformations improve urinary tract stone detection and density measurements compared with routine axial and coronal images.

MATERIALS AND METHODS

Forty-five consecutive patients who underwent MDCT for suspected urolithiasis were included. Two radiologists independently determined the number of stones on 5-, 3-, and 1.25-mm axial, 5- and 3-mm coronal, and 5-mm coronal MIP images. The reference standard was obtained by consensus review using all six datasets. Stone density was determined for all calculi 4 mm or larger on all datasets.

RESULTS

There were a total of 115 stones. Reader 1 identified 111 (96.5%), 112 (97.4%), 97 (84.3%), 102 (88.7%), 99 (86.1%), and 85 (73.9%) stones and reader 2 identified 105 (91.3%), 102 (88.7%), 85 (73.9%), 89 (77.4%), 89 (77.4%), and 76 (66.1%) stones on the MIP, 1.25-mm axial, 3-mm axial, 3-mm coronal, 5-mm coronal, and 5-mm axial images, respectively. Both readers identified more stones on the MIP images than on the 3- or 5-mm axial or coronal images (p < 0.0001). The mean difference in stone attenuation compared with the thin axial images was significantly less for the MIP images (44.6 HU) compared with 3-mm axial (235 HU), 3-mm coronal (309 HU), and 5-mm coronal (329.6 HU) or axial images (347.8 HU) (p < 0.0001).

CONCLUSION

Coronal MIP reformations allow more accurate identification and density measurements of urinary tract stones compared with routine axial and coronal reformations.

How accurate is unenhanced multidetector-row CT (MDCT) for localization of renal calculi?

PURPOSE

To investigate the correlation between unenhanced MDCT and intraoperative findings with regard to the exact anatomical location of renal calculi.

DESIGN, SETTING, AND PARTICIPANTS

Fifty-nine patients who underwent unenhanced MDCT for suspected urinary stone disease, and who underwent subsequent flexible ureterorenoscopy (URS) as treatment of nephrolithiasis were included in this retrospective study. All MDCT data sets were independently reviewed by three observers with different degrees of experience in reading CT. Each observer was asked to indicate presence and exact anatomical location of any calcification within pyelocaliceal system, renal papilla or renal cortex. Results were compared to intraoperative findings which have been defined as standard of reference. Calculi not described at surgery, but present on MDCT data were counted as renal cortex calcifications.

RESULTS

Overall 166 calculi in 59 kidneys have been detected on MDCT, 100 (60.2%) were located in the pyelocaliceal system and 66 (39.8%) in the renal parenchyma. Of the 100 pyelocaliceal calculi, 84 (84%) were correctly located on CT data sets by observer 1, 62 (62%) by observer 2, and 71 (71%) by observer 3. Sensitivity/specificity was 90-94% and 50-100% if only pyelocaliceal calculi measuring >4 mm in size were considered. For pyelocaliceal calculi≤4 mm in size diagnostic performance of MDCT was inferior.

CONCLUSION

Compared to flexible URS, unenhanced MDCT is accurate for distinction between pyelocaliceal calculi and renal parenchyma calcifications if renal calculi are >4 mm in size. For smaller renal calculi, unenhanced MDCT is less accurate and distinction between a pyelocaliceal calculus and renal parenchyma calcification is difficult.

Noncontrast multidetector CT of the kidneys: utility of 2D MPR and 3D rendering to elucidate genitourinary pathology

To encourage routine use of 2D multiplanar reconstructions (MRPs) and 3D renderings when interpreting noncontrast computed tomography (CT) of the kidney, as this practice can unveil findings related to the kidney or its vasculature that are not apparent on axial sections. Inspecting the kidneys or characterizing CT findings with both axial sections and MPRs may facilitate identification of vascular and neoplastic pathology.

Assessment of urinary tract calculi with 64-MDCT: The axial versus coronal plane

OBJECTIVE

The objective of our study was to compare the detection rate, conspicuity, and size measurements of urinary tract calculi on coronal reformations versus the axial plane using 64-MDCT.

MATERIALS AND METHODS

For this retrospective study, 80 consecutive CT examinations performed for clinical diagnosis of renal colic or for the assessment of known nephrolithiasis were evaluated. All studies were stripped of patient identifiers, and the axial and coronal plane images of each study were randomized and presented to two abdominal radiologists. For each study, the radiologists recorded the number and location of stones, diagnostic confidence and stone conspicuity (subjectively on a 2-point scale), and stone size. The standard of reference was data from a consensus reading with the study coordinator examining the same parameters on images in both planes of each patient. Detection rates were compared between planes using logistic regression with generalized estimating equations to account for multiple stones per patient.

RESULTS

On consensus reading, 272 stones were identified. For all renal stones, the coronal plane detected more stones as compared with the axial plane (p < 0.001). For stones smaller than 5 mm, a higher proportion received the maximal conspicuity score on the coronal plane than on the axial plane (p < 0.001). Both reviewers better estimated stone size on the coronal plane than the axial plane (p = 0.02); their axial plane measurements underestimated stone size by 13.4% (mean).

CONCLUSION

The detection of stones and estimation of maximal stone diameter were improved using coronal reformations. The conspicuity of stones and diagnostic confidence in identifying stones smaller than 5 mm in diameter were also improved on the coronal plane.

Computed tomography in the nontraumatic renal causes of acute flank pain

Renal colic pain due to obstructing stone is the main renal cause of acute flank pain. However, other causes may be responsible for the same clinical findings, including acute pyelonephritis, acute vascular conditions, and hemorrhage. The purpose of this review is to describe the differential diagnosis, the computed tomographic findings and pitfalls, and the role and impact of computed tomography in the diagnosis and management of the renal causes of acute flank pain.

Secondary signs of non-enhanced CT prior to laser ureterolithotripsy: is treatment outcome predictable?

PURPOSE

To correlate the presence of secondary signs of non-enhanced computed tomography (NECT) in renal units harboring ureteral calculi with intraoperative findings and treatment outcome after holmium:yttrium-aluminum-garnet laser (Ho:YAG) ureterolithotripsy.

SUBJECTS AND METHODS

Two-hundred patients were prospectively included after ureteral calculi were detected on NECT. All patients underwent Ho:YAG ureterolithotripsy at the Medical University of Vienna. All CT studies were reviewed by one specialized uroradiologist blinded to pre- and postoperative parameters for secondary signs as renal enlargement, perinephric stranding, ureteral dilation, periureteral edema, and ureteral rim sign. The impact of secondary signs on intraoperatively-verified impaction and treatment outcome was evaluated.

RESULTS

Of the 200 patients 85 (42.5%) harbored proximal and 115 (57.5%) harbored distal ureteral calculi. The stone-free rates for proximal and distal calculi were 80% and 97%, respectively. Although proximal stone location and intraoperatively-verified impaction correlated significantly with stone-free rates (P < 0.0001, P = 0.01), the presence of secondary signs could not predict intraoperatively-verified stone impaction or stone-free rates (renal enlargement: P = 0.2, P = 0.5; perinephric stranding: P = 0.7, P = 0.5; ureteral dilation: P = 0.7, P = 0.7; periureteral edema: P = 0.8, P = 0.06; ureteral rim sign: P = 0.8, P = 0.3).

CONCLUSION

Preoperative secondary signs seen on NECT in patients harboring ureteral calculi do not correlate with intraoperative findings of impaction, and do not predict treatment outcome after Ho:YAG ureterolithotripsy.

Imaging modalities for urolithiasis: impact on management

PURPOSE OF REVIEW

Urolithiasis is a common urological problem, often requiring efficient workup, accurate diagnosis, and treatment. The purpose of this review is to summarize the imaging modalities employed for the diagnosis of calculi and the caveats of different clinical situations.

RECENT FINDINGS

Noncontrast computed tomography has become the most universally used imaging tool for diagnosing urolithiasis, although ultrasound and magnetic resonance imaging maintain specific roles. Noncontrast computed tomography may provide prognostic information regarding the success of specific management strategies for urolithiasis. Additionally, noncontrast computed tomography is being tested in lower-radiation dose protocols with promising results.

SUMMARY

Considering the well supported accuracy and relative ease of use of noncontrast computed tomography, it has become a logical choice for the urologist to use the technique as a diagnostic tool for stone disease. The future of imaging for intervention and surveillance of stone disease lies in the continued progress of noncontrast computed tomography in terms of patient safety. This will need to be done by developing low-dose radiation computed tomography that can replicate the efficacy of current noncontrast computed tomography.