Image quality and dose comparison among screen-film, computed, and CT scanned projection radiography: applications to CT urography.

PURPOSE: To evaluate image quality and dose for abdominal imaging techniques that could be used as part of a computed tomographic (CT) urographic examination: screen-film (S-F) radiography or computed radiography (CR), performed with moving and stationary grids, and CT scanned projection radiography (CT SPR). MATERIALS AND METHODS: An image quality phantom underwent imaging with moving and stationary grids with both a clinical S-F combination and CR plate. CT SPR was performed with six CT scanners at various milliampere second and kilovolt peak settings. Entrance skin exposure (ESE); spatial, contrast, and temporal resolutions; geometric accuracy; and artifacts were assessed. RESULTS: S-F or CR images, with either grid, provided image quality equivalent to that with the clinical standard, S-F with a moving grid. ESE values for both S-F and CR were 435 mR (112.2 microC/kg [1 mR = 0.258 microC/kg]) with a moving grid and 226 mR (58.3 microC/kg) with a stationary grid. All CT SPR images provided inferior spatial resolution compared with S-F or CR images. High-contrast objects generated substantial artifacts on CT SPR images. Compared with S-F, CR and CT SPR provided improved resolution of small low-contrast objects. The contrast between iodine and soft-tissue-mimicking structures on CT SPR images acquired at 80 kVp was twice that at 120 kVp. CT SPR images with acceptable noise levels required a midline ESE value of approximately 300 mR (77.4 microC/kg) at 80 kVp. CONCLUSION: S-F and CR provided better spatial resolution than did CT SPR. However, CT SPR provided improved low-contrast resolution compared with S-F, at exposures comparable to those used for S-F or CR.

Extrapulmonary lymphangioleiomyomatosis and lymphangiomatous cysts in tuberous sclerosis complex.

OBJECTIVE: To describe the clinical manifestations, imaging findings, and histologic features of extrapulmonary lymphangioleiomyomatosis (LAM) in the tuberous sclerosis complex (TSC). DESIGN: We retrospectively reviewed institutional medical records since 1940 to identify patients with TSC and extrapulmonary LAM. MATERIAL AND METHODS: Of 403 patients with TSC, 3 had pulmonary and extrapulmonary LAM and retroperitoneal lymphangiomatous cysts. The clinical, imaging, and histologic features of these three patients were summarized, including analysis of biopsy specimens by conventional histology, immunohistology, radiolabeled ligand-binding assays, and tissue culture. RESULTS: The three young women had characteristic dermatologic findings of TSC and pulmonary LAM. Two patients were of normal intelligence, and one had a recent history of contraceptive use. All three patients had intra-abdominal lymphangiomatous cysts, uterine LAM, and renal angiomyolipomas. Renal and uterine biopsy specimens demonstrated positive immunostaining for melanoma-related antigens and expression of estrogen and progesterone receptors by ligand-binding assay and immunohistology. Cells cultured from LAM tissue of one of the patients exhibited a mitogenic response to estradiol. CONCLUSION: Clinically significant extrapulmonary LAM is a rare manifestation of TSC and may occur in women with this disease who also have pulmonary LAM. The clinical features of these patients confirm the importance of sex steroids in the development of these lesions. Immunohistochemical findings suggest that LAM and angiomyolipomas have a neuroectodermal origin. The development of lymphangiomatous cysts in these patients is probably due to smooth muscle proliferation in lymph vessels, which can result in lymphatic obstruction.

Renal stone disease in autosomal dominant polycystic kidney disease.

Nephrolithiasis is an important manifestation of autosomal dominant polycystic kidney disease (ADPKD), which occurs in approximately 20% of patients. It should always enter the differential diagnosis of flank pain in patients with ADPKD. The diagnosis is hindered by the distorted anatomy of the polycystic kidneys and the frequent occurrence of parenchymal and cyst wall calcifications, and requires demonstration of the relationship to the collecting system by intravenous urography and/or computed tomography. Computed tomography is the most sensitive imaging technique for detection of stones or calcifications, whereas intravenous urography is the most sensitive for visualization of the intrarenal collecting system. Precaliceal tubular ectasia can be detected in 15% of patients with ADPKD and nephrolithiasis, but this association may not be specific to ADPKD. The composition of the stones is most frequently uric acid and/or calcium oxalate. Metabolic factors are important in their pathogenesis. Distal acidification defects may be important in a few patients, while an abnormal transport of ammonium, low urine pH, and hypocitruria are the most common abnormalities. The treatment of nephrolithiasis in patients with ADPKD is not different from that in patients without ADPKD. Extracorporeal shock wave lithotripsy and percutaneous nephrostolithotomy in patients with early disease and normal renal function are not contraindicated.

Renal vein and inferior vena cava tumor thrombus in renal cell carcinoma: CT, US, MRI and venacavography.

Renal cell carcinoma has a propensity to extend as tumor thrombus into the renal vein and inferior vena cava (IVC). The preoperative assessment for the presence and extent of renal vein and IVC tumor thrombus is important for planning appropriate surgical resection. Imaging procedures [CT, ultrasound (US), MR, venacavography] were correlated with surgical findings and pathology in 431 consecutive patients who had a radical nephrectomy for renal cell carcinoma. Ninety-nine (23%) patients had tumor thrombus extending at least into the main renal vein. Of these, 29 had tumor thrombus extending within the IVC. Patients were classified into two groups based on the surgical extent of tumor thrombus. Group A patients had no tumor thrombus or had tumor thrombus only in the renal vein proximal to the site of surgical ligation. Group B patients had tumor thrombus that extended to or beyond the distal renal vein at the site of surgical ligation. Forty-one patients had Group B tumor thrombus. Group B tumor thrombus was not seen in a renal cell carcinoma that was smaller than 4.5 cm. The sensitivity of CT for detecting Group B tumor thrombus was 79% and that of US was 68%. However, a much higher percentage of US examinations were technically indeterminate. In the patients who had either MR or venacavography, both imaging procedures were 100% sensitive for detecting group B tumor thrombus. Magnetic resonance imaging and venacavography appear to be the most sensitive means of identifying tumor thrombus.

Role of ultrasound in medical management of patients with renal stone disease.

Eighty-three patients with radiographically opaque renal stones were evaluated prospectively with ultrasound and compared to KUB (kidneys, ureters, bladder) with tomograms (KUB/T) to further define the use of ultrasound in the evaluation of renal calculi. The presence or absence and the size, number, and location of stones were analyzed and correlated for each modality. Ultrasound detected the presence of renal stones in 77 of 83 (93%) patients. However, all of the stones were detected on ultrasound in only 60% of these patients. Thirty percent (80 of 269) of the papillary-calyceal stones seen on KUB/T were missed on US; 66% of the stones missed measured 2 mm or less. Although ultrasound can be used for detection of intrarenal stones, KUB/T is a more accurate imaging examination for determination of size and number of small stones.

Vasculogenic impotence. Duplex and color Doppler imaging.

Varicoceles, although only occasionally symptomatic, are reported to occur in 20% to 50% of infertile or subfertile men. Ligation or occlusion of the spermatic vein in these patients has improved semen quality in many instances. Recently, it has been recognized that varicoceles can be bilateral or subclinical and thus detected only by imaging. Sonographic diagnosis of varicoceles and percutaneous occlusive therapy are reviewed in this article.

Congenital cystic disease of the seminal vesicle.

Thirteen cases of congenital seminal vesicle cysts with pathologic correlation were diagnosed between 1970 and 1988. Twelve of the 13 patients had ipsilateral renal anomalies. Intravenous urography, performed in 11 of the 13 patients, demonstrated associated renal anomalies. Computed tomography, performed in nine of the 13 patients, demonstrated associated renal anomalies and displayed the cystic seminal vesicles. Transabdominal or endorectal ultrasonography, performed in eight patients, allowed characterization of the seminal vesicle masses as cystic. Magnetic resonance imaging, performed in three of the 13 patients, accurately demonstrated dilated ejaculatory ducts into which ectopic ureters inserted. The fluid in the seminal vesicle cysts had an increased signal intensity on T1- and T2-weighted sequences. Seminal vesiculographic study demonstrated anomalous communications with the seminal tract. Cystic disease of the seminal vesicles can be either congenital or acquired; congenital cysts are associated with anomalies of the ipsilateral mesonephric duct.

Hepatic cyst infection in autosomal dominant polycystic kidney disease.

To characterize the syndrome of hepatic cyst infection in autosomal dominant polycystic kidney disease (ADPKD) and to review its diagnosis and management, we retrospectively studied five such cases in patients from our institution and nine detailed case reports from the literature. The clinical manifestations were an acute (58%) or subacute (42%) febrile illness, typically associated with tenderness in the right upper quadrant, leukocytosis, a very high erythrocyte sedimentation rate, but minor abnormalities of liver function tests. Bacteremia was present in 7 of 11 patients. Enterobacteriaceae grew in pure culture from the cyst fluid in 9 of 12 patients. Complex cysts were observed by ultrasonography (in four of eight patients), computed tomography (in six of nine), and magnetic resonance imaging (in two of two). 111In leukocyte scans were positive in all four patients in whom they were done, and 67Ga scans were positive in only one of three patients. An unfavorable outcome was observed in six of seven patients treated with only antibiotics, in contrast with one of seven patients who received antibiotics and early drainage. In two patients, ciprofloxacin cyst levels were 2.3 and 4.8 times higher than the level in serum; in a third patient, cyst levels remained in therapeutic range 30 hours after the last dose of ciprofloxacin, at which time serum levels were undetectable. Clinical and laboratory features and the use of modern scanning techniques facilitate a prompt diagnosis of infection in hepatic cysts in ADPKD. The treatment of choice is a combination of percutaneous drainage and antimicrobial therapy.

Association of hypokalemia, aldosteronism, and renal cysts.

The recognition of renal cysts in two patients with chronic hypokalemia and the renal effects of hypokalemia in certain species of animals prompted this study of the possible association of hypokalemia and renal cysts in patients with primary aldosteronism or primary renal potassium wasting. Using CT scans, we studied 55 patients with primary aldosteronism, of whom 24 had cysts (44 percent). The cysts were more frequent in patients with adrenal tumors than in those with idiopathic adrenal hyperplasia. Sixteen of the 26 patients with tumors (62 percent) had renal cysts, which were often multiple and located in the medulla. Lower plasma potassium levels and higher serum aldosterone levels, urinary aldosterone excretion, and plasma renin activity were correlated with the extent of the cystic disease. Sequential observations indicated that prolonged hypokalemia can be accompanied by the development of renal scarring and that the size and number of cysts can decrease markedly in some patients after the removal of an adrenal adenoma. The association of hypokalemia, aldosteronism, and renal cysts was also supported by the finding of multiple medullary cysts in two patients with primary renal potassium wasting. We conclude that chronic hypokalemia is accompanied by enhanced renal cytogenesis and may lead to interstitial scarring and renal insufficiency. Renal cysts are thus dynamic structures whose growth can be influenced by hormonal or pharmacologic interventions.

Duplex and color Doppler sonographic evaluation of vasculogenic impotence.

One hundred eighty patients with suspected vasculogenic impotence were evaluated with conventional penile duplex sonography with spectral analysis and color Doppler imaging. Measurements of mean peak systolic and end-diastolic velocities were obtained from the cavernosal arteries before and after intracavernosal injections of papaverine. Sixty-one patients were examined with dynamic cavernosography and cavernosometry, and 12 patients were studied with selective internal pudendal and penile arteriography. All five patients with abnormal arteriography had mean peak systolic velocities in the cavernosal arteries of less than or equal to 25 cm/sec (sensitivity, 100%; 95% confidence interval, 48-100%) after the injection of papaverine. Six of the seven patients with normal arteriography had mean peak systolic velocities of greater than 25 cm/sec (specificity, 85.7%; 95% confidence interval, 42-100%) after injection of papaverine. By using data from a receiver-operating-characteristic curve, we determined that end-diastolic velocities in the cavernosal arteries of greater than or equal to 5 cm/sec after the injection of papaverine correctly identified patients with excessive venous leakage on cavernosometry; the sensitivity was 90% (95% confidence interval, 77-97%) and the specificity was 56% (95% confidence interval, 30-80%). The addition of color Doppler sonography made the detection of vessels easier and the correction of the Doppler angle more accurate, resulting in more rapid and accurate acquisition of data. Penile duplex sonography with spectral analysis and color Doppler imaging are sensitive and noninvasive means of examining patients with potential vasculogenic impotence.

Low-osmolality contrast media: a current perspective.

Intravascular radiographic contrast media play a major role in diagnostic imaging. Recently, low-osmolality contrast media (LOCM) have become available in the United States. Because of their lower osmolality, these new agents cause fewer undesirable physiologic effects and fewer adverse reactions than do conventional agents after intravascular administration. Unfortunately, the cost of LOCM is substantially higher than the cost of conventional contrast media. Appropriate use of these newer, more expensive contrast agents must be based on a thorough knowledge and understanding of their chemistry, physiologic features, and relative safety. Some questions remain about these new agents. Further studies are needed to determine the nephrotoxicity of LOCM relative to that of conventional agents. In addition, LOCM have less anticoagulant capacity than do the conventional media; therefore, clotting may occur when the LOCM and blood mix in syringes and small catheters. This potential decrease in anticoagulation and its clinical implications should be further investigated. Finally, the mortality rate associated with use of LOCM needs to be determined in future studies in large numbers of patients.

Seminal vesicle imaging.

The purpose of this paper is to enhance the understanding of CT, MRI and US images of the seminal vesicles. Accurate interpretation of images requires knowledge of normal anatomy, embryology and pathology. Anatomy and a spectrum of abnormalities are reviewed and discussed. Cases are from an analysis of clinical and surgical files to show the diagnostic features of various cystic diseases of the seminal vesicles. Tissue characteristics of the seminal vesicles on CT, MRI and US images are emphasized.

Intravenous urographic technique.

In these times of rapid advances in radiographic imaging, intravenous urography should be performed in an optimal way. The urographic examination should involve consultation between the referring physician and the radiologist. Necessary patient information should be accessible. McClennan said "patient selection for urographic studies should be efficacious with the radiologist exerting appropriate control so that the urogram is truly a consultative imaging service integrated into the total patient management." We share this view, and it is an extension of the philosophy of practice emphasized by other leaders in uroradiology. Cost containment, new imaging technologies, risk/benefit considerations, and evolving patterns of patient care have had a significant influence on genitourinary tract imaging. In addition, current debate about contrast media, digital radiography, efficacy, and utilization will undoubtedly have an influence on imaging during the next decade. Utilization of intravenous urography has decreased significantly in the past 15 years. Our volume of examinations has declined approximately 50% since 1970. This decline in our practice is attributed to several complex factors such as previous overutilization of screening urography for hypertension; the impact of US and CT for evaluation of obstruction, retroperitoneal disease (adenopathy and fibrosis), renal failure, and renal masses; concern about contrast medium-induced renal failure; and fewer repeat studies because of improved quality of intravenous urography in general radiology practice. In addition, overutilization of urography in patients with hematuria, prostatism, history of urinary tract infection, etc, continues to be debated in the medical community. In our integrated group practice, we have also observed overutilization of "high-tech" procedures in lieu of urography for evaluation of suspected urinary tract disease. Swings of the pendulum are inevitable in diagnostic imaging because of evolving technology and the art of medical practice. Although some differences of opinion about the details of urographic technique and indications for urography may exist, most would agree on the philosophy of producing a high-quality urographic examination. That philosophy focuses on producing the highest quality examination in each patient so that a diagnosis of normal or abnormal can be made accurately and confidently. Failure to demonstrate the entire urinary tract is a common cause of diagnostic error and one that can largely be eliminated by careful attention to the technical details of the examination.

The association of nephrolithiasis and autosomal dominant polycystic kidney disease.

Despite the frequency and morbidity of nephrolithiasis in autosomal dominant polycystic kidney disease (ADPKD), this association has not been subject to a detailed study. One hundred fifty-one of 751 ADPKD patients seen at the Mayo Clinic between 1976 and 1986 had nephrolithiasis. Seventy-four had passed calculi or had stones surgically removed. Stone analysis was available in 30 patients: uric acid, calcium oxalate, calcium phosphate, and struvite were present in 56.6%, 46.6%, 20%, and 10%, respectively. Calculi were observed in 71 of 79 patients with excretory urograms available for review. Faintly opaque and bull's eye stones, probably containing uric acid, were present in 12.7% and 14.1% of these patients, respectively. Precaliceal tubular ectasia was observed in 15.5%. Ninety-seven patients had preserved renal function (serum creatinine less than 1.5 mg/dL) at the initial evaluation. Six were excluded because they had other known causes of stone disease. The most common metabolic abnormality in the remaining 91 patients was hypocitric aciduria (ten of 15 patients with measurements). The urine pH in the first voided morning specimens (5.66 +/- 0.05) was significantly lower than that of an unselected control population (5.92 +/- 0.03, P less than 0.001). Hyperuricosuria, hyperoxaluria, and hypercalciuria were observed in six of 32 (18.8%), six of 31 (19.4%), and three of 39 (9.7%) patients with preserved renal function. The composition of the stones, the frequency of hypocitric aciduria, and the low urine pH (possibly related to the defect in excretion of ammonia described in ADPKD), suggest that metabolic, along with mechanical, factors are responsible for the frequent occurrence of nephrolithiasis in this disease.