Abdominal radiography after CT reveals urinary calculi: a method to predict usefulness of abdominal radiography on the basis of size and CT attenuation of calculi

CT-Based Determination of Ureteral Stone Volume: A Predictor of Spontaneous Passage

INTRODUCTION AND OBJECTIVES

Which ureteral stone can pass spontaneously? It is hard to answer this question exactly. The size and location of the stone are the most important predictors. However, there is still a considerable gray zone that needs to be clarified. We try to identify the role of stone volume (SV) in the prediction of spontaneous passage (SP).

MATERIALS AND METHODS

Seventy-eight patients with a solitary ureteral stone were retrospectively evaluated. Ureter SV measurements were taken in three planes and were calculated using the following formula: V = (X) × (Y) × (Z) × 0.52. SVs, and the longest diameters (LDs) were compared between patients who passed stones spontaneously and those who needed intervention.

RESULTS

The SVs and LDs were significantly lower in patients who passed stones spontaneously than in patients who required intervention (41.2 ± 35.5 vs 128.1 ± 91.1 mm(3), p = 0.001; 5.7 ± 1.8 vs 7.4 ± 1.7 mm, p = 0.001). The optimum cutoff values were 7.0 mm and 52.6 mm(3) for the LD and SV, respectively. For those stones of ≤7 mm, the volumes of the stones that could and could not pass did not differ significantly. However, the volume of the stones >7.0 mm that could pass was significantly higher than of those that could not. SP was 30.6% for stones >7 mm; however, when we removed the stones >52.6 mm(3), SP increased to 75% for stones higher than 7 mm (p = 0.001).

CONCLUSIONS

To classify ureteral stones using only one parameter such as stone diameter may lead to heterogeneity within the group. SV may be used in addition to size to determine a more definite homogeneous group to predict SP more precisely.

Immediate or delayed SWL in ureteric stones: a prospective and randomized study

The objective is to compare immediate and delayed SWL as a treatment for ureter stones between 5 and 20 mm. Patients who applied to the emergency department with single, radio opaque ureteric stone of 5-20 mm size were included in the study. Patients were randomized into immediate and delayed SWL groups. SWL were carried out after pain relief in the delayed group. Maximum of three SWL sessions were applied to the patients with stones of 5 mm or bigger in diameter, leaving at least 3 days interval in-between. Stone-free rate after first session was similar in two groups. When CIRF was also considered as success, the success rate of SWL in the immediate SWL group was higher after first session (p = 0.02). Immediate SWL had a greater success rate in upper ureteric stones (p = 0.019). Overall average time required for elimination of stones was shorter in immediate SWL group than delayed SWL group (p = 0.033). The success rate after first SWL session (including CIRF) was 59 % for patients with chronic pain in the delayed group and 100 % for patients with acute pain in the immediate group. According to the hydronephrosis grade, success rates were 71 and 44.4 % for patients with grade 1 or no hydronephrosis in the immediate SWL group, and for patients with grade 2 or larger hydronephrosis in the delayed SWL group, respectively, after first SWL session. Immediate SWL insures stone-free status in a shorter time in cases with renal colicky pain and ureteral stones, particularly upper ureteral stones.

Useful prediction of ureteral calculi visibility on abdominal radiographs based on calculi characteristics on unenhanced helical CT and CT scout radiographs

AIMS

To determine whether visibility of ureteral calculi on plain radiographs of the kidney, ureter and bladder (KUB) could be predicted based on characteristics on unenhanced helical computed tomography (UHCT) and CT scout radiographs (CTSR).

METHODS

One hundred and twenty-three patients diagnosed with 140 ureteral calculi on UHCT, had undergone both UHCT and KUB within 24 h and before calculus passage or intervention were included. The visibility of ureteral calculi on KUB and CTSR as well as their sizes, locations and densities on UHCT were recorded. The association of CTSR/UHCT characteristics of ureteral calculi and their visibility on KUB were analysed. Multivariate analyses using logistic regression were computed as predictors for visibility on KUB.

RESULTS

Of the 140 calculi, 56 (40%) and 98 (70%) were visible on CTSR and KUB respectively. All calculi detectable on CTSR were also visible on KUB. Multivariate analyses of the 84 CTSR undetectable calculi revealed that non-middle ureteral location and higher calculi densities on UHCT were significant predictors of visibility on KUB. All non-middle ureteral calculi with density > 800 Hounsfield units (HU) were visible on KUB. Of 23 calculi in the middle ureter or with density < 200 HU, 17 (74%) were invisible on KUB.

CONCLUSIONS

Ureteral calculi characteristics on UHCT and CTSR are useful for predicting their visibility on KUB. Patients with visible calculi on CTSR or non-middle ureteral calculi with density > 800 HU are suitable for KUB to follow-up calculi status.

Acute Flank Pain Secondary to Urolithiasis: Radiologic Evaluation and Alternate Diagnoses

This article discusses the radiologic management of the patient who has acute flank pain. It describes the evolution of radiologic imaging in patients who present with acute symptoms caused by suspected urolithiasis, the advantages of unenhanced helical CT and the limitations of abdominal radiography, intravenous urography, and ultrasonography in this setting, and the alternative diagnoses encountered within the urinary tract, abdomen, and pelvis.

Size Matters: A Survey of How Urinary-Tract Stones are Measured in the UK

BACKGROUND AND PURPOSE

Stone size forms the basis of management pathways in patients with urolithiasis. We carried out a questionnaire-based audit to find out how stone size is routinely measured by radiologists in the UK.

MATERIALS AND METHODS

A series of 831 anonymous questionnaires concerning how stone size is assessed using four imaging modalities--plain abdominal radiograph (KUB film), intravenous urogram (IVU), ultrasound, and CT--were sent to 277 radiology departments. Following the survey, a substudy at our institution compared urologists (N = 10) and radiologists (N = 5) in estimating the size of a large (26-mm) and small (11- mm) calculus on KUB films.

RESULTS

Of the questionnaires, 425 were returned, and 421 were analyzed. Of these, 85% were from consultants, 14% from trainees/middle grades, and 1% "unspecified." In total, 92% of the respondents were radiologists (10% uroradiologists) and 8% urologists. Estimation of stone size ("guestimation") from KUB films and IVUs was used by 40% and 36% of radiologists, respectively, whereas graded rulers were used by 57% and 59%, respectively. For ultrasound scans and CT, electronic measurement was the favored method (81% and 73%), but guestimation was still used by 10% and 15%, respectively. When assessing the KUB films and IVU, 59% and 61% of urologists, respectively, also used guestimation. The substudy revealed a significant difference among radiologists in the accuracy of size estimation for the 11-mm stone (mean estimated size 9.6 mm; P = 0.02, one-sample t-test).

CONCLUSION

A large proportion of radiologists use guestimation for assessing stone size on KUB films and IVU. Even when electronic measuring aids were available for CT and ultrasonography, guestimates remained prevalent. Our substudy showed that radiologists significantly underestimated the smaller stone.

CT evaluation of urinary lithiasis

Unenhanced CT has been demonstrated to be the most accurate and efficient diagnostic imaging means to evaluate urinary lithiasis, with capability of directing management, and has become well accepted by radiologists, urologists, and emergency department physicians such that it is now the standard of practice. It is the duty of the radiologist to be aware of proper technique and the details of interpretation. The radiologist also has a duty to be aware of the limitations of unenhanced CT for detection and evaluation of various nonstone disorders, particularly with poor patient selection, and to extend the examination if appropriate. Controversies and future developments include cost containment with care for the selection of patients. Further attempts to reduce radiation exposure should be made. Optimal CT technique is not needed in general merely to detect urinary lithiasis. A consensus should be developed regarding use of CT in pregnant patients. Further improvements in the digital scout view would be useful for following patients.