Retroperitoneal masses not arising from major solid organs are uncommon. Although there is no simple method of classifying retroperitoneal masses, a reasonable approach is to consider the masses as predominantly solid or cystic and to subdivide these into neoplastic and nonneoplastic masses. Because the treatment options vary, it is useful to be able to differentiate these masses by using imaging criteria. Although the differential diagnosis of retroperitoneal masses can be narrowed down to a certain extent on the basis of imaging characteristics, patterns of involvement, and demographics, there is still a considerable overlap of imaging findings for these masses, and histologic examination is often required for definitive diagnosis. Computed tomography (CT) and magnetic resonance (MR) imaging play an important role in characterization and in the assessment of the extent of the disease and involvement of adjacent and distant structures. Familiarity with the CT and MR imaging features of various retroperitoneal masses will facilitate accurate diagnosis and staging for aggressive lesions.

Acute, potentially life-threateningsystemic reactions to contrast media are less frequent with lower osmolality, nonionic contrast agents, but they are not totally eliminated. Severe reactions remain a reality in all radiology departments. Typical reactions to contrast media include nausea and/or vomiting, scattered to extensive urticarla, bronchospastic reaction, hypotenslon (isolated) with compensating tachycardia, anaphylactoid reaction, vagal reaction, cardiovascular collapse, convulsion, and seizure. For each type of reaction, rapid recognition and initiation of specific corrective therapy enhance response and minimize side effects of drugs. Specific drugs for treating each reaction type are reviewed, Including recommended dose, contraindlcations, and alternative choices. An approach to the high-risk patient and prevention of acute systemic reactions is discussed and pretreatment protocols are outlined.

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Percutaneous removal of most urinary tract calculi may be performed as a 1-stage effort with techniques and skills developed recently in the specialties of urology and radiology. Ultrasonic fragmentation of most calculi was done to permit their extraction. Percutaneous ultrasonic lithotripsy was performed on 250 consecutive (a single exception) patients bearing stones that required removal. Targeted calculi were removed successfully from 97 per cent of these patients. One patient required surgical lithotomy. The previous 100 patients with stones underwent surgical lithotomy with 96 per cent success. Complications of percutaneous ultrasonic lithotripsy appeared equitable with those of surgical lithotomy. Of the patients who underwent percutaneous ultrasonic lithotripsy 6 (6 per cent) required extended hospital days or additional procedures for management of complications. None of these patients required a surgical incision. Anesthesia times were similar for both groups--average 159 plus or minus 4 (standard error) minutes for percutaneous ultrasonic lithotripsy and 193 plus or minus 8 minutes for surgical lithotomy. Hospital recovery days averaged 5.5 plus or minus 0.3 for percutaneous ultrasonic lithotripsy and 8.4 plus or minus 0.5 for surgical lithotomy (p less than 0.01). Associated costs averaged $7,203 plus or minus 55 for lithotripsy and $8,849 plus or minus 660 for lithotomy (p less than 0.01). The number of narcotic administrations per patient (days 1 to 5 postoperatively) averaged 9.88 plus or minus 0.70 for lithotripsy and 16.82 plus or minus 0.78 for lithotomy (p less than 0.01). The average patient who underwent percutaneous ultrasonic lithotripsy felt capable of full activity 2.0 plus or minus 0.2 weeks following stone removal, whereas no patient who underwent previous surgical lithotomy recalls a recovery period of less than 3 weeks (p less than 0.01). We believe that most upper urinary tract calculi may be removed cost-effectively with a percutaneous approach. Compared to surgical lithotomy, percutaneous ultrasonic lithotripsy may result in rapid convalescence with diminished pain.

When compared with didactic lecture, high-fidelity simulation-based training of contrast reaction management shows equal results on written test scores but improved performance during a high-fidelity severe contrast reaction simulation scenario.