Radiologic evaluation of urolithiasis

Digital Radiography Using Laser Stimulated Luminescence for Evaluation of Urinary Calcifications

One hundred consecutive patients were investigated with both a conventional film-screen combination and digital radiography using a laser stimulated luminescence technique in order to evaluate differences in detecting urinary tract stones. All patients were referred either for follow-up of previously known stones or for symptoms. The images were reviewed by two radiologists who had the single clinical information that the patients might have urinary stones. Following review, the two techniques were compared and a consensus was obtained. One hundred and eighteen stones were found in 41 patients without any statistical differences in sensitivity between the two imaging systems.

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.

Urocystolith detection: comparison of survey, contrast radiographic and ultrasonographic techniques in an in vitro bladder phantom

Urocystoliths of 9 mineral types from 437 canine patients submitted to the University of Minnesota Urolith Bank were imaged in a urinary bladder phantom. Imaging techniques simulated were survey radiography, pneumocystography, double contrast cystography (two iodine concentrations) and real-time ultrasonography (3.5 MHz, 5.0 MHz, 7.5 MHz). Imaging techniques were compared for accuracy of urocystolith detection, accuracy of urocystolith enumeration, and tendencies for over or undercounting. Across urocystolith mineral types, the false negative rates (no urocystoliths detected in a given case) for survey radiographs range from 2 to 27%. Pneumocystographic techniques are one-half as likely to yield false negative results as are survey radiographic techniques. Underestimates of urocystolith numbers and false negatives are likely using 80 mg iodine/ml double contrast cystography because calcium-based urocystoliths are isopaque in this contrast medium dilution. The 200 mg iodine/ml double contrast cystographic techniques are unlikely to yield false negative diagnoses even for very small (< or = 1.0 mm) urocystoliths and is comparable to pneumocystography for detection and slightly better for enumeration. The likelihood of an ultrasonographic false negative for urocystoliths decreases with increasing MHz. Under optimal conditions using a 7.5 MHz mechanical sector transducer, the false negative rates were comparable to double contrast cystography, but rates increased notably with lower MHz transducers.

CT findings in general practice patients with suspected acute sinusitis

PURPOSE

To study CT findings in general practice patients with a clinical diagnosis of acute sinusitis, and to examine the interobserver variation between 2 radiologists with regard to their CT evaluation.

MATERIAL AND METHODS

Two hundred and one patients were examined with coronal CT images of the paranasal sinuses within 2 days of the clinical diagnosis. Patients with chronic sinusitis were excluded. Fluid level or total opacification of any sinus were used as evidence of sinusitis.

RESULTS

One hundred and twenty-seven (63%) patients had fluid level or total opacification in a sinus region, most in more than one region. One hundred and fifteen had CT signs of sinusitis in the ethmoid region, 84 in the maxillary, 18 in the frontal, and 10 in the sphenoid. Forty-nine patients had a negative Ct. In the evaluation of interobserver agreement, the overall assessment of the CT yielded a kappa value of 0.70.

CONCLUSION

The study demonstrated great variation in the CT findings in general practice patients with suspected acute sinusitis. More than one sinus region was affected in most patients in whom sinusitis was confirmed by CT imaging; the most common combination was ethmoid and maxillary sinuses. The interobserver agreement was substantial.