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Biomedical subjects

J H Newhouse

Publications and source records attributed to J H Newhouse.

At least 19 recordsLinked to original sources
PubMed1992

Evaluation of teleradiology for interpretation of intravenous urograms.

The diagnostic yield of a commercial teleradiology/picture archiving and communication system (ATT-Philips Comm View T/PACS) was evaluated for 100 urograms. A single image from each examination was digitized (2048 x 1684 x 12-bit pixels) and transmitted from a satellite hospital over a T-1 line using the T/PACS system. The video display of each digitized image was reviewed independently by four radiologists. The same four radiologists reviewed the original film images at a different time without knowledge of their T/PACS interpretation. There was no statistically significant difference in the sensitivity for clinical findings between T/PACS (86%) and film (89%). The false positive rate, however, was significantly higher with T/PACS than with film (44 versus 32 false positive findings per 100 films). We conclude that T/PACS of the type studied here demonstrates sufficient sensitivity for the detection of clinically important urographic findings in the emergency setting. A final reading of the original films is still necessary, however, to assure appropriate specificity.

Contrast Media↗
PubMed1991

Clinical use of urinary tract magnetic resonance imaging.

MR imaging should not be used to evaluate the majority of the lesions described herein but should be reserved for specific clinical situations. The detection and differential diagnosis of adrenal masses is a legitimate application of this technique. The staging of renal tumors in patients in whom CT fails to do so may be accomplished by MR imaging. Establishment of patency of the renal veins and of surgical shunts involving these veins may be performed by MR imaging if Doppler ultrasonography proves unsatisfactory. MR imaging may differentiate between stable retroperitoneal fibrosis and malignant disease in patients in whom this differential is a problem. Hematomas may be distinguished from nonhemorrhagic fluid collections anywhere in the abdomen or pelvis. In selected patients, the local extent of certain bladder tumors may be evaluated by MR imaging when CT and biopsy fail to do so. In testicular disease, MR imaging may aid in the differential diagnosis of abnormalities that are not sufficiently characterized by ultrasonography, and MR imaging may detect undescended testes in some patients in whom ultrasonography fails to do so. In the future, wider application of fast scanning with bolus administration of soluble paramagnetic contrast agents may refine the differential diagnosis of adrenal masses and aid in the detection of renal masses. MR angiographic techniques ultimately may constitute a screening procedure for renal arteriostenosis. A subset of patients with prostate carcinoma may prove to benefit from local staging of the disease by MR imaging.

Adrenal Gland Diseases↗
PubMed1990

MRI of the adrenal gland.

Current status of magnetic resonance imaging (MRI) of the adrenal gland is reviewed, and basic techniques and sensitivity of MRI for differentiating histologic lesions are also discussed.

Adrenal Gland Diseases↗
PubMed1990

MR evaluation of renal space-occupying lesions: diagnostic criteria.

In order to assess the ability of magnetic resonance (MR) imaging to distinguish simple renal cysts from renal tumors, images from 53 patients with 74 lesions were reviewed. MR image characteristics, including signal strength and homogeneity for each lesion, were evaluated and compared with the final diagnoses. There were 53 cysts and 21 tumors. For 56 lesions (76%), MR allowed accurate diagnosis; on T1-weighted images, homogeneous low-intensity lesions were always cysts and inhomogeneous medium- or high-intensity lesions were always tumors. The remaining 18 lesions (24%) could not be distinguished, and T2-weighted images failed to improve differential diagnostic ability. In our experience, MR imaging allows differentiation of renal cysts and tumors less frequently than does computed tomography (CT) or ultrasound (US). MR criteria for simple renal cysts and tumors are offered, with the understanding that modification may be necessary as experience with these lesions increases.

Diagnosis, Differential↗
PubMed1990

Quadtree-based data compression of abdominal CT images.

An ROC study was performed to evaluate the effect of quadtree-based data compression on the diagnostic yield of CT images. Seventy images were selected from a series of consecutive abdominal/pelvic CT scans. Following the application of quadtree-based compression, all images were reviewed independently by three radiologists. The images were analyzed at six decreasing irreversible compression ratios (30.6:1 to 7.4:1), as well as after reversible compression (2.9:1). ROC curves reveal a gradual decrease in clinical accuracy with increasing compression ratios. At a compression ratio of 7.4:1, sensitivity for all major abnormalities was 99% with a specificity of 93%. As the compression ratio was increased to 30.6:1, sensitivity and specificity dropped to 75% and 83% respectively. Execution times for compression and decompression of the CT images with a PC-AT based digital radiography system varied from 24.7 to 18.5 seconds and from 16.2 to 5.1 seconds respectively, decreasing with higher levels of compression. We conclude that quadtree-based compression of abdominal CT images may have practical applications for a PC based digital radiography system.

Algorithms↗
PubMed1990

Application of region of interest definition to quadtree-based compression of CT images.

A quadtree-based data compression algorithm can provide different levels of compression within and outside of regions of interest (ROIs). The current study shows whether ROI compression can provide greater compression or diagnostic accuracy than uniform quadtree compression. In 75 single CT images from 75 consecutive abdominal examinations, 43 abnormalities were identified and surrounded by ROIs. Three radiologists interpreted the images following (1) 50:1 compression of the entire image; (2) ROI compression at five decreasing compression ratios (with 50:1 compression outside the ROI); and (3) reversible (lossless) compression of the entire image. Reversible compression (compression ratio 3:1) yielded a sensitivity of 96%. ROI compression of 15:1 was achieved with no loss of sensitivity; ROI compression of 28:1 yielded a sensitivity of 91% (not significantly different). At any given compression ratio, diagnostic sensitivity was greater with ROI compression than with uniform quadtree compression. For purposes of image archiving, quadtree-based ROI compression is superior to uniform compression of CT images.

Algorithms↗
PubMed1990

Mn (III) hematoporphyrin. A potential MR contrast agent.

Manganese (III) hematoporphyrin (MnHP), a new and stable complex, was prepared, and its toxicity and magnetic resonance (MR) imaging properties were evaluated. In tests of acute and subacute toxicity, no deaths resulted from bolus intravenous injections of 13 or 19 mumols/kg of MnHP, but there was a 33% mortality when the dose was 38 mumols/kg. Laboratory results were normal in the surviving rats. Ultraviolet- visible spectroscopy of the urine and serum of two rats injected 24 hours previously with 38 mumols/kg MnHP revealed no free HP, suggesting in vivo stability of MnHP. Finally, using a standardized imaging protocol, there was a mean increase of 37% in the liver-to-muscle intensity ratios in four rats injected 24 hours previously with 25 mumols/kg MnHP when compared to paired controls (P less than .005). In addition, obvious visual increase in the signal intensity of the liver on T1-weighted images was seen in animals tested with 13 and 19 mumols/kg of MnHP. The results suggest that further evaluation of MnHP as an MR contrast agent for the liver is warranted.

Animals↗
PubMed1989

Nephrogenic adenoma of the bladder: urographic spectrum.

Nephrogenic adenoma is a rare, proliferative response of urothelium to urinary infection or injury of the bladder mucosa. Histologically, the lesion resembles proximal tubules of the nephron. While it can occur throughout the urinary tract, it usually appears in the bladder, with diverse radiographic manifestations. Of 6 patients with nephrogenic adenoma of the bladder, 3 presented with masses in the bladder and 2 with irregularities of the bladder mucosa on urography, while 1 showed no focal urographic abnormalities. There were no distinctive radiographic features of nephrogenic adenoma that would allow it to be differentiated from tumor or other inflammatory lesions. Although it is considered benign, bladder involvement may be extensive and eradication of the tumor may be difficult.

Adenoma↗
PubMed1989

Evaluation of a quadtree-based compression algorithm with digitized urograms.

The effect of a quadtree-based data-compression algorithm on the diagnostic yield in digitized radiographs was studied for 100 urograms. Each image was digitized and reviewed at nine decreasing compression ratios ranging from 90:1 to 4.2:1, followed by a review of the uncompressed digital images. Four radiologists independently reviewed the digitized images and the original radiographs and agreed on a reference standard of 201 findings. Sensitivity, measured by the number of findings noted on the compressed digital images, decreased with increasing compression ratios at and above the 11:1 level. No loss of sensitivity was noted with a compression ratio of 4.2:1. Sensitivity decreased more precipitously for calcifications than for soft-tissue masses. Only a minimal loss of sensitivity for bilateral renal function was noted, even with high compression ratios. False-positive rates were unaffected by compression. The authors conclude that quadtree compression ratios of 11:1 and higher may result in loss of sensitivity in clinically relevant findings.

Algorithms↗
PubMed1989

CT of primary lymphoma of the liver.

Primary lymphoma of the liver is a rare disease. In each of six cases, a large, often poorly defined mass of low attenuation was present within the liver. Four lesions originated in the right lobe and two originated in the left lobe. Satellite nodules were seen at presentation in one case and developed after presentation in two others. Other features, such as enhancement after contrast administration, necrosis, and calcification, were variable. Three of six lesions had areas of very low density, suggestive of necrosis. One mass had calcifications. After IV contrast administration, no enhancement occurred in three tumors, patchy enhancement occurred in two, and an enhancing ring was seen in the remaining tumor. The radiologic presentation of primary lymphoma of the liver differs from that of secondary involvement of the liver in systemic lymphoma. Whereas secondary lymphoma is often diffusely infiltrative and difficult to detect on CT, the lesions of primary lymphoma of the liver are easily identified on CT scans even before the administration of IV contrast material. Although rare, primary lymphoma of the liver should be included in the differential diagnosis of a large, hypodense liver mass on CT.

Adult↗
PubMed1988

The emergence of hepatic fibrosis and portal hypertension in infants and children with autosomal recessive polycystic kidney disease. Initial and follow-up sonographic and radiographic findings.

Long-term imaging and clinical findings are reported in six children whose polycystic kidney disease was detected in infancy or early childhood. Over time (2 years to 20 years) all patients developed portal hypertension from hepatic fibrosis, a problem primarily noted in recessive pattern polycystic kidney disease. Mild renal failure (two patients) was accompanied by serious systemic hypertension in the same patients. In one family, one of the babies also showed dilated right hepatic ducts. Imaging studies included urography and CT although recently ultrasonography was the method of choice. The relative renal and hepatic manifestations in these patients so changed with time that it would seem fallacious to attempt to use rigid classifications based on findings at initial diagnosis.

Child, Preschool↗
PubMed1988

MRI of multilocular cystic nephroma.

We report the magnetic resonance imaging (MRI) findings in 2 patients with multilocular cystic nephromas. Both underwent MRI immediately prior to resection. The images accurately reflected the morphology of the tumors: in each, the capsule was hypointense on all pulse sequences. Varied intensities of signal from the fluid in the visualized locules presumably represented differing concentrations of old hemorrhage and protein. In one case soft tissue elements became hyperintense on T2-weighted images. We speculate that MRI of multilocular cystic nephromas will produce imaging features that are highly suggestive, but not always pathognomonic, of the disease.

Adult↗
PubMed1988

Continent urinary diversions: review of current surgical procedures and radiologic imaging.

Continent urinary diversions are currently gaining wide acceptance as alternatives to the ileal conduit following cystectomy for neoplasm or bladder dysfunction. Clean, intermittent catheterization of the reservoir (pouch) at regular intervals obviates the inconvenience of wearing an external stomal appliance. A variety of surgical techniques have been described for continent pouches. These techniques make use of the small bowel alone (Camey and Kock techniques) or a combination of cecum and terminal ileum (Indiana, Mainz, Penn, and King techniques). The optimum pouch protects the upper tracts by prevention of reflux, provides urinary continence, and has sufficient capacity to require catheterization no more frequently than every 3-6 hours. Simplified construction techniques for the commonly encountered pouches are graphically presented, and a method is suggested for the study of continent diversions.

Cecum↗
PubMed1988

MR imaging of portal vein thrombosis.

MR imaging is emerging as a potential means of detecting portal venous thrombosis (PVT). Therefore, we attempted to establish specific criteria with which to diagnose PVT on conventional spin-echo images. In a retrospective review of 342 consecutive abdominal MR scans performed with a 0.5-T magnet, we identified nine patients with persistent signal in the portal vein and used the findings in these patients to establish criteria with which to diagnose PVT. We subsequently applied these criteria to 109 additional consecutive abdominal MR scans performed with the same magnet. Fifteen cases were found in which all images showed either (1) signal involving the entire width of the portal vein lumen, which approximated (with T1 weighting) and exceeded (with T2 weighting) the intensity of the hepatic parenchyma in images in which the hepatic veins showed a complete flow void or (2) complete nonvisualization of the portal vein and its major branches in images that showed a flow void in portal venous collaterals and hepatic veins. All patients had unequivocal findings of PVT on at least one other imaging study (CT or sonography) or at surgery. Although the sensitivity of these signs could not be calculated, their specificity was 100%. We conclude that in the presence of these signs, the diagnosis of PVT can be made with confidence.

Adolescent↗
PubMed1988

The relationship between renal scarring and stone disease.

The urographic findings of focal clubbing of the renal calices and associated parenchymal scarring usually prompt a diagnosis of chronic pyelonephritis, which is frequently thought to be due to ongoing or previous vesicoureteral reflux. However, we noticed that upper tract stone disease appeared to be the condition that most often preceded or accompanied caliceal clubbing and parenchymal scarring in adults. To test the hypothesis that stones were the most common cause of this renal abnormality, we analyzed the IV urograms in 1500 consecutive patients for evidence of upper tract stone disease, vesicoureteral reflux, and caliceal clubbing and scarring. Of 39 patients with clubbing and scarring, 67% had stone disease, but only 8% had a history of reflux. Of 90 patients with stone disease, 29% had clubbing and scarring. We conclude that, in adults, upper tract stone disease may be the most important etiologic factor in the production of renal caliceal clubbing and scarring.

Cicatrix↗
PubMed1987

CT and sonography of advanced urinary tract tuberculosis.

Sonographic and Ct examinations were performed prospectively on 14 patients with advanced urinary tract tuberculosis who had undergone serial urography. Sonography and CT showed abnormalities in the affected kidney in each patient. Detailed morphologic information (patterns of calcification and hydronephrosis) and functional status (nephrogram and urogram) were better shown by CT than by urography; sonography showed the fewest morphologic details. CT is probably at least as accurate as urography in detecting advanced urinary tuberculosis; sonography appears to be less accurate than either CT or urography.

Adult↗