Are screening serum creatinine levels necessary prior to outpatient CT examinations?

PURPOSE: To determine the percentage of outpatients with elevated serum creatinine levels (>/=2.0 mg/dL [177 micromol/L]) and associated reported risk factors for contrast material-induced nephrotoxic reactions (eg, diabetes, renal disease, male, age >/= 60 years, chemotherapy) who undergo computed tomography (CT) and to define a true high-risk population. MATERIALS AND METHODS: The serum creatinine levels were obtained in a total of 2,034 consecutive outpatients (969 male, 1,065 female) who underwent contrast material-enhanced CT. In addition, selected patient charts were reviewed to determine the presence of risk factors for contrast material-induced nephrotoxic reactions. RESULTS: Only 66 (3.2%) had an elevated serum creatinine level. Risk factors were identified in 64 of the 66 (97%) patients with an elevated serum creatinine level. Renal disease was present in 62 of the 66 (94%) patients. Two of the 66 patients with an elevated creatinine level had no identifiable risk factors, representing 0.1% of the total number of patients. CONCLUSION: The data suggest that the majority of patients with a serum creatinine level of at least 2.0 mg/dL (177 micromol/L) will be identified by screening for risk factors. Careful patient screening, especially for renal disease, at the time of scheduling could result in considerable savings in terms of radiology man-hours expended and laboratory costs.

1998 Joseph E. Whitley, MD, Award. Relationship between American College of Radiology in-training examination scores and American Board of Radiology written examination scores. Part 2. Multi-institutional study.

RATIONALE AND OBJECTIVES: The authors assessed the relationship between resident performance on the American College of Radiology in-training examination and subsequent American Board of Radiology written examination. MATERIALS AND METHODS: Percentile scores from the in-training examination (low score, < 20 percentile) and written board examination (low score, < 25 percentile) were collected for 513 residents from 11 university-based programs over a 7-year period. Mean in-training examination scores were compared for the high- and low-score written board examination groups. In-training examination scores were correlated with the written board examination scores. An odds ratio was calculated for the association between in-training examination and written board examination scores; this was adjusted for resident Alpha Omega Alpha (AOA) status, clinical training prior to radiology residency, the year the written board examination was taken, program size, and regional location of the program. RESULTS: The mean in-training examination scores were significantly higher in the high-score than the low-score written board examination group (P = .0001). There was a significant correlation between the in-training examination score and the written board examination score (P = .0001). The crude all-high in-training scores-written board scores odds ratio was 9.618, and the adjusted all-high odds ratio was 7.595. The final model included resident AOA status. CONCLUSION: Resident average in-training examination score was a strong predictor of the written board examination score, as noted in the earlier report. The resident with a low in-training examination score is at risk for poor performance on the written board examination.

Imaging and radiologic management of upper urinary tract infections.

Most infections of the upper urinary tract respond promptly to antibiotic therapy and imaging is not necessary. Patients with urinary obstruction, diabetes, or immunocompromise are more likely to develop complicated infection, abscess, or have unusual organisms. Chronic granulomatous processes involving the kidney are usually related to recurrent bacterial infections. Again, stone disease or obstruction is often an underlying problem. In those patients who do not respond promptly to treatment or have a more complicated clinical picture, imaging can assess the severity and extent of disease. CT scan is the study of choice for diagnostic evaluation in these patients and directs percutaneous intervention when appropriate. Placement of drainage catheters is often curative but also may allow the patient to stabilize until surgical treatment is accomplished. One exception is the diagnosis of pyonephrosis, which may be accomplished more easily by ultrasound. In these cases, PCN placement is generally needed and is performed under fluoroscopic guidance. Ultimately, however, definitive surgical intervention often is needed to relieve the underlying obstruction.

Relationship between American College of Radiology in-training examination scores and American Board of Radiology written examination scores.

RATIONALE AND OBJECTIVES: To retrospectively evaluate the association between resident performance on the American College of Radiology in-training examination and performance on the American Board of Radiology written examination. METHODS: Percentile scores from the in-training examination (low score, < 20th percentile) and written board examination (low score, < 25 percentile) were collected for 58 residents in a large, university-based program during a 6-year period. Mean in-training examination scores were compared for the high score and low score written board groups. In-training examination scores were correlated with the written board scores, and odds ratios were calculated for the association between in-training examination and written board scores. Adjusted in-training examination and written board odds ratios were calculated for Alpha Omega Alpha status and prior clinical training. RESULTS: The mean in-training examination scores were statistically significantly higher in the high score written board group (P = .0001). There was significant correlation between the in-training examination and the written board scores (P = .05). There was a significant association between a resident's average in-training examination score and written board score. Alpha Omega Alpha status was associated with high written board scores, and prior clinical training was associated with low written board scores (not significant). CONCLUSION: The resident's average in-training examination score was a strong predictor of the written board score. The resident with a low in-training examination score is at risk for poor performance on the written board examination and may benefit from remedial training.

Efficacy of supine versus prone biliary lithotripsy: an in vitro study.

Clinical extracorporeal shock wave lithotripsy (ESWL) results have shown that the smaller the gallstone fragments following ESWL, the faster the patient will become stone-free. At ESWL, an attempt is made to produce sand-like fragments that will easily pass through the cystic and common bile ducts. Sixteen pairs of gallstones of equal shape, size, and composition were harvested from cholecystectomy specimens and then fragmented on the Dornier MPL-9000 lithotripter (Dornier Medical Systems, Inc.), individually, in a phantom oriented to duplicate either supine or prone patient positions. The number and size of remaining fragments were compared following the supine versus prone treatments. The 32 stones, ranging from 5-15 mm in diameter, received 1,500 shock waves at 21 kV. Fragments with a maximal diameter of greater than or equal to 4 mm were measured and counted after 750 and 1,500 shock waves. Fragments greater than or equal to 4 mm were found in four out of 16 stones treated supine (25%) and 16 out of 16 stones treated prone (100%). The largest residual fragment regardless of size for each stone pair occurred in the prone group in 14 out of 16 cases (88%). Biliary lithotripsy performed with supine positioning results in more efficacious gallstone fragmentation in this in vitro model; these findings suggest that supine positioning for patients could improve fragmentation and treatment success.

Abnormalities of the gallbladder after extracorporeal shock-wave lithotripsy: imaging findings.

To qualify for treatment with biliary extracorporeal shock-wave lithotripsy (ESWL), patients must have sonograms that show gallstones and oral cholecystograms (OCGs) that show normal opacification (indicating normal function) of the gallbladder. We have noted that sonograms and OCGs made 6 weeks to 6 months after ESWL sometimes show abnormalities that were not visible on these images before ESWL. In these cases, the gallbladder appears contracted on sonograms and is poorly visualized on OCGs. To determine how often this occurs and to study its significance, we analyzed the posttreatment sonograms and OCGs in 174 patients who underwent ESWL. After ESWL, sonograms showed a contracted gallbladder and OCGs showed poor function in 25 (14%) of the 174 patients. One patient (4%) was lost to follow-up. In 17 (68%) of the 25 patients, the abnormalities were transient (findings on sonograms and OCGs returned to normal by 12 months after ESWL). In the other seven patients (28%), the abnormalities persisted (all seven subsequently had a cholecystectomy); this is a cholecystectomy rate twice that in the patients with normal findings on sonograms and OCGs after ESWL (20/149 or 13%). All 25 patients with abnormalities after ESWL had gallstone fragments at 6 weeks, as did 146 of the 149 patients with normal-appearing gallbladders after ESWL. When these abnormalities persist (in approximately one third of patients), cholecystectomy is often required. The cause of the abnormalities is unknown, although chronic cholecystitis, a process that is not detectable by pre-ESWL imaging techniques, seems likely.

The use of transcutaneous electrical nerve stimulation during the biliary lithotripsy procedure.

Transcutaneous electrical nerve stimulation (TENS) has been suggested as a means to reduce the amount of intravenous analgesia/sedation in patients undergoing extracorporeal shock wave lithotripsy (ESWL). A retrospective analysis of 79 ESWL procedures on 73 consecutive unselected patients was done in an attempt to determine the effectiveness of TENS in reducing the amount of intravenous fentanyl citrate and/or midazolam HCl needed to control pain and anxiety during the ESWL procedure. The study was divided into two parts: (1) all patients receiving TENS (n = 44) versus a non-TENS group (n = 35), and (2) comparison of the early (n = 22) and late non-TENS (n = 22) groups against each other; separately the late non-TENS group was compared to the entire TENS group. In the study, TENS reduce the amount of fentanyl citrate needed to control anxiety by 22.9% (P less than 0.025). No difference was noted when the early and late non-TENS group of patients were compared to each other. A gender difference was noted with a significant reduction in the dose of fentanyl citrate only in female patients receiving TENS (45.4%). Likewise, there was a significant reduction in the dose of midazolam HCl only in males who had TENS (38.9%). The data suggests that TENS may be a useful addition to reduce the amount of sedation and analgesia during ESWL.

Comparison of ultrasonography and oral cholecystography in biliary lithotripsy. I. Screening patients.

Ultrasound and oral cholecystography (OCG) are both used to evaluate candidates for biliary lithotripsy. Some investigators have suggested abandoning the OCG, believing that sufficient screening information can be obtained from ultrasound. This study compares ultrasound and OCG in assessing the size and number of gallstones, both in vitro and in vivo. In the in vitro model, 35 gallstones, divided into 20 groups, were separately suspended in dilute contrast media in a phantom, and examined by ultrasound and simulated OCG by each of three gastrointestinal radiologists. In the in vivo study, the ultrasound and OCG examinations from 53 patients were independently reviewed by three radiologists. The number and size of the stones were recorded in both studies. In the in vitro study, the stone size was measured within 2 mm of the actual size by OCG in 23/35 stones (66%) and by ultrasound in 4/35 stones (11%). The correct number of stones was determined by OCG in 19/20 groups (95%), and by ultrasound in 14/20 (70%). In the in vivo study, all readers saw the same number of stones in 40/50 (80%) patients by OCG and 33/49 (67%) patients by ultrasound. Statistical analyses revealed correlation coefficients for OCG greater than those for ultrasound in each comparison. The size of the largest stone was within 2 mm by all readers in 26/51 (51%) of patients by OCG and 20/47 (43%) patients by ultrasound. Oral cholecystography is more reliable than ultrasound for the determination of size and number of stones in patients being screened for biliary lithotripsy.

Comparison of ultrasonography and oral cholecystography in lithotripsy. II. Determining retreatment.

Both ultrasonography (US) and oral cholecystography (OCG) are being used to evaluate patients after extracorporeal shock wave lithotripsy (ESWL) for gallstones. Criteria for retreatment after the initial ESWL are usually related to the size of the residual fragments. This study examines the efficacy of ultrasound and OCG for determining both the size and number of stone fragments in the gallbladder in an in vitro model and in patients. Ultrasonography and OCG examinations using an in vitro ESWL phantom with ten groups of stones, and on 39 patients, were reviewed independently by three radiologists to determine both the size and number of stone fragments. For the in vitro study, the three readers estimated the correct number of fragments, or the next closest range, in 87% of observations by OCG and in 43% by US. The size of the largest fragment was measured within 1 mm of its actual size in 87% of observations by OCG and 20% by US. Correlation coefficients for the mean measurements of the three readers versus the actual fragment size and number were greater for OCG than for US. For the in vivo study, the three readers agreed in 47% of the OCG versus 32% of US examinations with respect to the number of fragments, and in 65% of OCG compared to 40% of US studies with respect to size of the largest fragment. Multiple statistical analyses demonstrate that these differences are statistically significant. A discrepancy among the readers concerning whether a patient was eligible for retreatment occurred in 15% of OCG as compared to 45% of US studies. Both the in vivo and in vitro studies indicate that there is more interobserver reproducibility for OCG than for US, and that OCG is more reliable in making the decision concerning patient eligibility for retreatment following lithotripsy.

Shock wave lithotripsy of gallstones: results and 12-month follow-up in 174 patients.

At the authors' institution, as part of the on-going Dornier National Biliary Lithotripsy Study, 174 patients with gallstones were randomly assigned to receive either ursodeoxycholic acid (UDCA) or placebo for 6 months after undergoing extracorporeal shock wave lithotripsy (ESWL). Six weeks after ESWL, 40 (23%) patients were re-treated for gallstone fragments larger than 5 mm in diameter. No significant difference in the UDCA- and placebo-treated patients was noted. The overall 6- and 12-month stone-free rates for all patients with initially noncalcified stones were as follows: UDCA patients, 31% and 36%, respectively, and placebo patients, 21% and 23%, respectively (P less than .05). In patients with a single, noncalcified gallstone that was at most 20 mm in diameter, the 12-month stone-free rates were as follows: UDCA patients, 60%, and placebo patients, 33% (P less than .01). Patients with noncalcified stones that were 11-20 mm in diameter who were treated with UDCA had a higher rate of stone clearance than placebo patients. At 6 months, the authors' previous study demonstrated no significant difference in the two groups of patients. However, the stone-free rate at 12 months was noted to be significantly higher for patients with a single, noncalcified stone that was at most 20 mm in diameter begun on UDCA than for all other groups of patients.

Renal transplant rejection. Limited value of duplex Doppler sonography.

Over a two-year period, 275 duplex Doppler ultrasound (US) examinations were performed on 75 renal allograft recipients. Retrospective visual analysis of the Doppler tracings was compared to concurrent clinical findings and to biopsy results. One hundred eight of the 176 Doppler examinations (61%) that showed acute rejection clinically or histologically were interpreted as rejection, while 80 of 99 examinations (81%) in clinically normal patients were interpreted as normal. Two hundred thirty-four examinations had resistive index (RI) calculations. Seventy-two of 141 examinations (51%) with RI less than 0.70 had clinical or biopsy evidence of rejection. Studies compared with only concurrent biopsies revealed that 35 of 39 US examinations interpreted as rejection were confirmed histologically, but only one of 32 examinations that appeared normal sonographically was histologically normal. The low sensitivity of Doppler US, whether by waveform analysis or RI calculation, makes it a poor screening test for acute rejection. The findings support the conclusion that Doppler sonography cannot replace biopsy in the evaluation of renal transplant dysfunction, particularly when the waveform analysis is normal and the RI less than 0.70.

Biliary lithotripsy versus cholecystectomy: a cost-utility analysis.

Evaluating the economic impact of medical procedures is of increasing importance in the American health care system, and this is especially true in the case of new medical technologies. Both the cost and the outcome of a treatment, and its alternatives must be evaluated. A cost-utility analysis was performed to compare cholecystectomy with biliary lithotripsy accompanied by bile acid therapy. Using a Markov approach, a model was designed to project expected cost and quality-adjusted survival over a 5-year period in patients with solitary stones of less than or equal to 20 mm in diameter. The viewpoint of the analysis was chosen to be that of the general society, since it can be considered as a consensus of all interest groups. Direct costs were obtained from hospitals in Atlanta, Georgia; indirect costs are based on average United States earnings. Utility was estimated using a model that combines different scales of well-being with an underlying etiology. The findings indicate that from society's point of view for all patients meeting lithotripsy inclusion criteria, based on this cost-utility analysis, biliary lithotripsy would be the procedure of choice.

Extracorporeal shock wave lithotripsy of gallstones: results and 6-month follow-up in 141 patients.

A study of biliary shock wave lithotripsy of gallstones sponsored by Dornier Medical Systems, Munich, began in the United States in May 1988 to evaluate the efficacy and safety of extracorporeal shock wave lithotripsy (ESWL) and the need for adjunctive therapy with ursodeoxycholic acid (UDCA). One hundred forty-one symptomatic patients with one to three gallstones 5-30 mm in diameter were randomized to treatment. One week before ESWL, patients were given either UDCA or placebo. This treatment was continued for 6 months. All patients underwent follow-up at predetermined intervals. According to the protocol, re-treatment for fragments larger than 5 mm in diameter could be performed only at 6 weeks; 26 (18%) of the 141 patients were retreated. At 6 months, the stone-free rates for single stones were as follows: patients with noncalcified stones receiving UDCA, 29%; patients with noncalcified stones receiving placebo, 24%; and patients with partially calcified stones receiving either UDCA or placebo, 6%. No significant difference was noted between the UDCA and placebo groups. At 6 months, the stone-free rates in patients with single, noncalcified stones 20 mm or less in diameter were 40% (UDCA) and 32% (placebo), which is superior to rates for those with solitary, noncalcified gallstones 21-30 mm in diameter and those with two or three stones.

Technical aspects of biliary extracorporeal shock wave lithotripsy.

Radiologic imaging procedures play a major role in the evaluation of the potential patient for biliary extracorporeal shock wave lithotripsy, both during the procedure and in follow-up evaluation. The treating physician must have a thorough knowledge of ultrasonography techniques. Lithotripsy requires continual monitoring and frequent reassessment to optimize targeting and fragmentation of the gallstones while maintaining patient comfort.

Biliary lithotripsy: in vitro analysis of gallstone fragmentation for equivalent stone volumes.

The relationship between gallstone fragmentation during extracorporeal shock wave lithotripsy (ESWL) and gallstone volume is poorly understood. Clinical results of ESWL show that the highest stone-free rate at 6 months occurs with radiolucent single gallstones 20 mm or less in diameter. In an in vitro study, individual gallstones from cholecystectomy specimens were divided by size and composition into nine single- and nine multiple-stone groups; the stones were then paired on the basis of similar volume. ESWL was performed in a phantom and the size of the largest fragment was measured at 500, 1,000, and 1,500 shock waves. At 1,500 shock waves, sandlike particles were present in six of nine single stones versus two of nine multiple stone groups; the mean size of the largest fragment at 1,500 shock waves was 2.1 mm (single) and 4.4 mm (multiple) in diameter. When corrected for volume, the authors' data suggest that single stones are more easily broken into fragments smaller than 5 mm in diameter than multiple gallstones. The implication, especially when spark-gap technology is used, is that more shock wave energy (ie, an increased number of shock waves at a higher kilovoltage) will be necessary to achieve the same results when treating patients with multiple stones versus a single gallstone with a similar stone volume.

Gallstone extracorporeal shock-wave lithotripsy: time and treatment considerations.

We evaluated 30 gallstone lithotripsy procedures performed on 27 patients with the Dornier MPL-9000 Lithotripter to determine how time was spent in the lithotripsy suite and to evaluate the various technical reasons for interrupting the administration of shock waves during the treatment. The procedure averaged 98 +/- 32 min total time in the lithotripsy suite. This included an average of 22 +/- 6 min before the treatment, 70 +/- 28 min for administration of shock waves, and 6 +/- 2 min after the treatment. The time required to deliver the shock waves did not correlate with patient age, sex, or weight; the number of gallstones; or the number or date of the treatment. However, a trend was seen toward an association between shorter treatment times and larger stone volumes. On the average, the administration of shock waves was interrupted every 48 shock waves for various reasons. Electronically changing the imaging plane of the in-line sonographic transducer to retarget the stone in the focal zone was by far the most frequent reason for interrupting shock-wave delivery, averaging 56 shock waves between changes. We conclude that extracorporeal shock-wave lithotripsy of gallstones is a time consuming and technically demanding procedure that requires continuous monitoring and frequent interruption in order to optimize targeting and fragmentation of the stone(s) while maintaining the patient's comfort.

Malakoplakia of the ureter and bladder.

Malakoplakia is an uncommon granulomatous inflammatory disease that most often involves the urinary tract. Typically, there is an associated urinary tract infection (UTI) by coliform organisms. Histologically, the Michaelis-Gutmann bodies are the hallmark of this disease. Radiographically, malakoplakia may simulate other inflammatory processes or even neoplasm as demonstrated in these two cases.