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Biomedical subjects

J F Platt

Publications and source records attributed to J F Platt.

At least 19 recordsLinked to original sources
PubMed1992

Renal dysfunction in hepatic disease: early identification with renal duplex Doppler US in patients who undergo liver transplantation.

To improve early detection of renal dysfunction in patients who undergo liver transplantation, a prospective study was performed with intrarenal duplex Doppler sonography before and after liver transplantation in 42 patients. The duplex Doppler findings were compared with multiple clinical and laboratory findings; patients were grouped on the basis of preoperative renal resistive index (RI) and serum creatinine level. The mean initial renal RI was elevated (.73 +/- .07 [standard deviation]); after transplantation, it was lower (.60 +/- .06) (P less than .001). Thirty-six patients had a normal serum creatinine level at the preoperative Doppler examination. Patients with an elevated renal RI (n = 19) had a greater chance of subsequent renal dysfunction (P less than .001), hemodialysis (P less than .01), longer stays in the intensive care unit (P less than .05), and longer hospital stays after surgery (P less than .05) than those with a normal renal RI (n = 17). In 34 patients the RI fell 10% or more after surgery and none died, whereas five of eight patients (62%) whose RI fell less than 10% died. Doppler analysis enabled identification of patients without azotemia whose course of disease before and after surgery was similar to that of patients with clinically recognized renal disease.

Adolescent↗
PubMed1992

Age dependency of the renal resistive index in healthy children.

It has recently been suggested that the resistive index (RI) in native kidneys of healthy children is age dependent; however, this relationship has not been completely defined or explained. In 110 kidneys in 71 healthy children aged newborn to 11 years, RIs were determined from peripheral sites (presumed to be arcuate, cortical, or distal interlobar arteries). The authors found the normal renal RI (the mean RI in each kidney) to be age dependent. The renal RI in children is commonly elevated above the upper normal limit in adults (0.70) in the 1st year of life, and the overall trend shows a decrease with age. From 4 years on, the likelihood is low (2% probability) that the RI is above 0.70. Variability of the renal RI from individual to individual was most marked in the first 6 months of life, with 51% (19 of 37) of these kidneys having an RI that would be considered abnormal by adult standards. It is concluded that the normal renal RI is age dependent, with an overall decreasing trend with increasing age. This age dependency of the renal RI and, hence, of the renal vascular resistance might be dependent on levels of active renin, as the maturational profile of the renal RI more closely parallels that of active renin than those of other renal functional parameters.

Aging↗
PubMed1992

Duplex Doppler evaluation of native kidney dysfunction: obstructive and nonobstructive disease.

Intrarenal duplex Doppler sonography can provide physiologic information reflecting the status of renal vascular resistance. Available data suggest 0.70 as a reasonable upper limit for normal intrarenal resistive index. Complete or significant partial urinary obstruction produces a prompt elevation in the resistive index that is not produced by purely nonobstructive dilatation; hence, Doppler imaging appears useful in evaluating the dilated, possibly obstructed kidney. In addition, intrarenal Doppler sonography may prove to be a useful noninvasive test to suggest the significance of partial obstruction. Nonobstructive renal disease also can cause elevation of the resistive index. Recent biopsy series, although correlating certain pathologic findings with resistive index, also indicate that renal Doppler sonography is not sensitive or specific enough to replace renal biopsy. To date, Doppler study of renal medical disease has proved most useful in two types of applications: monitoring of patients with renal disease known to produce resistive index elevation and differentiating between renal diseases where one produces more marked Doppler changes than the other. Resistive index is clearly not identical to creatinine level; in some instances the resistive index may provide unique noninvasive information regarding renal arterial resistance not available from conventional laboratory parameters.

Acute Kidney Injury↗
PubMed1991

Acute renal failure: possible role of duplex Doppler US in distinction between acute prerenal failure and acute tubular necrosis.

Ultrasonography (US) of the native kidneys is commonly requested for acute renal failure (ARF), although in most cases the examination results are negative. To detect changes in the Doppler waveform associated with ARF and determine whether Doppler US can provide significant diagnostic information not available with standard US, 91 patients with ARF were studied to determine a mean resistive index (RI) for each patient. Forty-six patients had acute tubular necrosis (ATN) with a mean RI +/- 1 standard deviation of .85 +/- .06, which was significantly higher than the mean RI of .67 +/- .09 in 30 patients with prerenal ARF (P less than .01). Fifteen patients had ARF due to non-ATN intrinsic renal disease (mean RI, .74 +/- .13). An elevated RI (greater than or equal to .75) occurred in 91% of patients with ATN versus only 20% of patients with prerenal azotemia. Patients with severe liver disease (hepatorenal syndrome) are a subset of those with prerenal ARF that accounted for most of the elevated RIs in this group. The study demonstrates that intrarenal Doppler US allows detection of changes associated with ARF far more often than standard US. More important, Doppler US may be helpful in distinguishing ATN from prerenal azotemia.

Acute Kidney Injury↗
PubMed1991

Renal transplant pyelocaliectasis: role of duplex Doppler US in evaluation.

To distinguish the obstructed from the nonobstructed dilated collecting system of transplanted kidneys without interventional diagnostic measures, the authors prospectively evaluated duplex Doppler analysis (determination of resistive index [RI]) in 35 renal transplant patients with pyelocaliectasis. Proof of the presence or absence of obstruction was obtained at interventional procedures in 18 patients and at clinical follow-up in 17. Thirteen kidneys were obstructed (mean RI, .81 +/- .06), while 22 had nonobstructive dilatation (mean RI, .66 +/- .07). The RI difference was statistically significant (P less than or equal to .01). Of 21 kidneys with a normal RI, only two had obstruction. In both of these, the obstruction was associated with a significant peritransplant collection of fluid due to a ureteral leak. In the seven obstructed transplanted kidneys with follow-up, the mean RI was .82 +/- .06 before nephrostomy and .67 +/- .05 after nephrostomy. Obstruction was a common cause of an elevated RI (greater than or equal to .75). Other causes of transplant dysfunction can be associated with an elevated RI and nonobstructed dilatation. More important, a normal RI should strongly argue against obstruction unless a ureteral leak is also present.

Adult↗
PubMed1991

Stones and infection in renal caliceal diverticula: treatment with percutaneous procedures.

Percutaneous treatment of symptomatic caliceal diverticula has expanded the application of uroradiologic intervention. To assess the safety and efficacy of these procedures, we have reviewed our experience with percutaneous management of 12 symptomatic caliceal diverticula, 10 with stones and two infected. Nine stone-bearing diverticula were punctured directly with subsequent tract dilatation, nephroscopic stone extraction, and cavity obliteration (six with fulguration and drainage and three with drainage alone). One case was approached indirectly by puncturing a distant calix, dilating the diverticular neck, and flushing the stones into the collecting system for extraction. This cavity was not treated. Two infected diverticula were punctured directly for drainage and obliteration (one by fulguration and one by tetracycline sclerosis). Complete stone extractions were accomplished in all 10 cases. In eight with clinical follow-up ranging from 4 months to 6 years, one stone has recurred and seven patients are asymptomatic. Follow-up urograms were available in eight of 10 patients in whom cavity obliteration was attempted; in six (75%) of eight, nonvisualization of the diverticulum indicated successful obliteration. Only one major complication (urinoma requiring drainage) occurred. We conclude that percutaneous procedures are safe and effective in treating infected or stone-bearing caliceal diverticula. Direct diverticular puncture for access and diverticular fulguration for cavity obliteration is our preferred technique.

Adult↗
PubMed1991

Transitional cell carcinoma of the bladder: patterns of recurrence after cystectomy as determined by CT.

CT scans have been recommended for examination of patients at risk for recurrent transitional cell carcinoma after cystectomy. For CT to be useful in this regard, the location and type of recurrences must be known, so that appropriate scans can be made. Therefore, we retrospectively studied CT scans in 27 postcystectomy patients with recurrent transitional cell carcinoma of the bladder to identify the type and location of the recurrent disease. Recurrence was documented by biopsy in 18 patients and by progression of disease shown on serial CT scans in nine patients. All 27 patients had pelvic CT, and 23 had concomitant abdominal CT. Tumor recurred at the cystectomy site in 10 (37%) of 27 patients, pelvic adenopathy was present in 18 (67%) of 27 patients, and retroperitoneal adenopathy was present in 13 (57%) of 23 patients. Tumor recurrence at the cystectomy site was associated with pelvic adenopathy in seven of 10 patients, and the cystectomy site was the solitary site of disease in the remaining three patients. Conversely, in 11 of 18 patients with pelvic adenopathy no recurrence was seen at the cystectomy site. Combined retroperitoneal and pelvic adenopathy was identified in 11 of 23 patients, but two patients had retroperitoneal lymphadenopathy as their only site of recurrence. Hepatic metastases were seen in seven (30%) of 23 patients; six of these seven patients had metastases elsewhere. In four of five patients in whom underestimation of recurrent disease occurred, the deep pelvis and/or deep perineal space were involved. Our results show that the pelvis is the most common site for recurrence. Cystectomy site or retroperitoneal nodal recurrences are usually accompanied by pelvic adenopathy, but the converse is not as common. Our findings of deep perineal and isolated abdominal recurrences indicate that proper protocol for CT follow-up of the postcystectomy patient should include abdominal scans and scans through the perineum.

Aged↗
PubMed1990

Ultrasound of the normal nongravid uterus: correlation with gross and histopathology.

Accurate assessment of uterine size and significance of uterine enlargement are common clinical problems. We examined 156 patients by sonography prior to scheduled hysterectomy. Uterine volumes from normal-sized uteri were calculated from the sonograms using the equation of a prolate ellipsoid formula, and these calculated volumes were highly correlated with actual measured uterine volumes. Mean values and normal ranges of uterine weight were determined. These values are of particular value in postmenopausal patients in whom subjective evaluation of uterine enlargement is often difficult. When a sonographically enlarged, but otherwise normal uterus is discovered, it may contain a leiomyoma or other pathology not morphologically detectable by ultrasound.

Age Factors↗
PubMed1990

Intrarenal arterial Doppler sonography in patients with nonobstructive renal disease: correlation of resistive index with biopsy findings.

The resistive index (RI), calculated from the duplex Doppler waveform, was compared with clinical and laboratory findings and the results of renal biopsy in 41 patients with nonobstructive (medical) renal disease. Kidneys with active disease in the tubulointerstitial compartment had a mean RI of 0.75 +/- 0.07. This was statistically significantly different (p less than .01) from the RI in kidneys with disease limited to the glomeruli (mean RI of 0.58 +/- 0.05). Acute tubular necrosis resulted in an elevated RI (mean RI = 0.78 +/- 0.03) as did vasculitis/vasculopathy (mean RI = 0.82 +/- 0.05). Patients with hypertension, proteinuria, or hematuria did not have kidneys with a significantly higher RI than did patients without these clinical factors. Kidneys found to be abnormally echogenic did not have an RI significantly different from kidneys of normal echogenicity. There was a weak correlation between creatinine level and RI value, reflected by a linear correlation coefficient of 0.34. In patients with normal renal RIs, the mean creatinine level was 1.7 +/- 1.7, whereas in those with abnormal RI values (greater than or equal to 0.70), the mean creatinine level was 3.7 +/- 3.6. We conclude that some forms of nonobstructive renal disease can produce changes in the Doppler waveform detectable by RI measurement. The production of Doppler waveform changes is strongly influenced by the site of the main disease within the kidneys. Active disease within the tubulointerstitial compartment (acute tubular necrosis, interstitial nephritis) or vasculitis/vasculopathy generally resulted in an elevated RI, whereas disease limited to the glomeruli, no matter how severe, did not significantly elevate the RI. Degree of renal dysfunction as indicated by serum creatinine level probably affects the Doppler waveform to some degree, but the relationship is weak.

Adolescent↗
PubMed1989

Duplex Doppler US of the kidney: differentiation of obstructive from nonobstructive dilatation.

Distinction of the obstructed from the nonobstructed dilated renal collecting system is a difficult problem often requiring interventional procedures and pressure measurements. The authors prospectively performed duplex Doppler ultrasound (US) evaluations in 21 kidneys (obstructed, n = 14; nonobstructed, n = 7) immediately before percutaneous nephrostomy. In addition, ten of the obstructed kidneys were evaluated with follow-up Doppler US after percutaneous nephrostomy. Renal obstruction caused a change in the Doppler waveform detected by means of the resistive index (RI). Thirteen of the 14 obstructed kidneys had a RI value greater than .70, while none of the nonobstructed kidneys had a RI value exceeding .70. Relief of the obstruction resulted in a reduced RI; in nine of ten kidneys, the RI was less than or equal to .70 (similar to that of the nonobstructed kidneys). When a dilated collecting system is being imaged, additional evaluation with duplex Doppler US may help distinguish obstructed from nonobstructed dilatation, which may be of particular benefit in patients with conditions that usually predispose them to collecting system dilatation.

Diagnosis, Differential↗
PubMed1989

Distinction between obstructive and nonobstructive pyelocaliectasis with duplex Doppler sonography.

Because animal studies have shown that renal obstruction increases renal vascular resistance, we theorized that obstruction would change the Doppler waveform. We studied the value of the resistive index (RI) calculated from the duplex Doppler waveform to distinguish between obstructive and nonobstructive pyelocaliectasis in 229 kidneys in 133 patients. The RI is the peak systolic frequency shift minus the minimum diastolic frequency shift, then divided by the peak systolic frequency shift. Duplex Doppler sonography was performed prospectively in 70 kidneys with pyelocaliectasis before the presence or absence of obstruction was established. In 54 of 70 kidneys, the presence or absence of obstruction was proved by interventional methods (percutaneous nephrostomy, antegrade or retrograde pyelography, loopography), and in the rest it was proved by body CT, excretory urography, or surgery. Thirty-eight kidneys were found to be obstructed, and 32 had nonobstructive dilatation. In addition, 159 kidneys without pyelocaliectasis were studied to identify possible limitations of Doppler sonography in the diagnosis of obstruction. Clinical history and laboratory data were used to determine that 109 of these kidneys were in normal subjects and 50 were in patients with nondilated renal disease. There was a significant difference between the mean RI of the obstructed (0.77 +/- 0.05) and the nonobstructed dilated (0.63 +/- 0.06) kidneys (p less than .01). Analysis of the receiver-operating-characteristic curve showed an RI of 0.70 to be a good discriminatory level for obstruction, resulting in a sensitivity of 92%, a specificity of 88%, and an accuracy of 90%. All 109 normal kidneys had an RI less than 0.70. Over half (27/50) of the kidneys in patients with nondilated renal disease had an elevated RI (greater than or equal to 0.70). Ninety-six patients had Doppler examinations on both kidneys, and in only six patients did the RI values of each kidney differ by more than 0.10; all six were proved to have unilateral obstruction. Use of duplex Doppler sonography should improve the specificity, and thus the accuracy, of sonography in the noninvasive diagnosis of obstruction and should be used when a dilated collecting system is identified.

Adolescent↗
PubMed1988

IV contrast material for abdominal CT: comparison of three methods of administration.

Despite a decade of experience, there is still no consensus as to the optimal IV contrast regimen for use in combined abdominal and pelvic CT scanning. In order to determine which regimen is most effective, 90 patients undergoing CT were prospectively randomized into one of three groups, depending on the method by which IV contrast material was administered: (1) a single bolus (150 ml or 175 ml, depending on the patient's weight) started when scans were made at the level of the dome of the diaphragm; (2) a split bolus delivered by means of a power injector, with the first bolus (100 or 125 ml) given when scans were made at the level of the dome of the diaphragm and the second bolus (50 ml) given when scans were made at the level of the iliac crest; (3) an initial hand-delivered bolus (100 or 125 ml) given when scans were made at the level of diaphragm, followed by rapid IV drip infusion of 50 ml throughout the remainder of the study. Quantitative comparison of pre- and postcontrast scans was performed at two levels: at the mid-liver to assess hepatic enhancement and 1 cm above the sacrosciatic notch to assess pelvic vascular enhancement. The single bolus provided better mean liver enhancement (46 H) than did either the split-bolus (36 H) or the bolus-drip (32 H) method (p less than .05). The last two methods achieved a sufficient aortocaval difference (greater than 10 H) to allow for evaluation of the liver in the nonequilibrium phase of contrast enhancement in which lesion detection is thought to be optimal. Mean enhancement of pelvic vessels was significantly better with the split bolus (arterial enhancement of 56 H, venous enhancement of 47 H) than with the single bolus (34 H, 31 H) or bolus-drip infusion (38 H, 35 H) (p less than .05). We conclude that the split-bolus method is optimal for routine combined abdominal and pelvic CT scanning. The bolus-drip method is the least effective method for administering the contrast material.

Clinical Trials as Topic↗
PubMed1988

Radiologic evaluation of the subcarinal lymph nodes: a comparative study.

Subcarinal lymph nodes are commonly involved by metastases from cancers of both the right and left lungs. No data exist on the relative accuracy of radiologic methods for evaluating subcarinal nodes. We prospectively studied lung cancer patients who were surgical candidates with CT, MR imaging (0.35 T), esophagography, and anteroposterior tomography. Forty-six patients who subsequently underwent thoracotomy had excision or sampling of subcarinal nodes at mediastinoscopy. All 46 had CT scans, 27 had MR imaging, 23 had esophagography, and 21 had anteroposterior tomography. Receiver-operating characteristic curves were constructed for each technique, and the area under each curve was calculated. MR and CT were nearly identical in subcarinal evaluation, with areas under the receiver-operating characteristic curves of 0.90 and 0.86, respectively; both were superior to esophagography (0.55) and anteroposterior tomography (0.61). The size threshold at which subcarinal nodes were considered abnormally enlarged in this lung cancer population was 11 mm in short axis for CT, agreeing with the size threshold previously reported for a normal population. The size threshold for abnormal nodal enlargement with MR imaging was 18 mm in short axis. We conclude that CT and MR imaging are comparable in the detection of subcarinal lymphadenopathy and are superior to both tomography and esophagography. Different size thresholds for metastatic subcarinal nodes are needed for CT and MR imaging to be comparable in overall performance.

Carcinoma, Non-Small-Cell Lung↗
PubMed1988

The inability to detect kidney disease on the basis of echogenicity.

With the use of new sonographic technology, we have observed that the echogenicity of kidneys is often equal to that of the liver in patients in whom there is no evidence of renal disease; this observation conflicts with the generally accepted notion that a normal kidney is always less echogenic than the liver. In order to reassess renal echogenicity as an indicator of disease, three experienced radiologists blindly reviewed the sonograms of the right kidney and liver in 153 patients. The prevalence of renal disease was 26% (40/153). Accepted sonographic criteria for abnormal renal echogenicity (kidney echogenicity greater than or equal to liver) were neither sensitive (62%) nor specific (58%) for renal disease, with a positive predictive value of 35%. Most of these inaccuracies occurred because 43 (72%) of 60 patients in whom renal echogenicity was equal to that of liver had normal renal function. If stricter criteria for abnormality were adopted (kidney echogenicity greater than liver), specificity (96%) and positive predictive value (67%) rose; however, sensitivity was only 20%. We conclude that renal echogenicity equal to the echogenicity of liver is not a good indicator of disease. Use of stricter criteria (kidney echogenicity greater than liver) provides a specific but insensitive test.

Adult↗
PubMed1988

Intraoperative spinal sonography in the evaluation of intramedullary tumors.

Seventeen intraoperative spinal sonographic examinations were performed in 14 patients with intramedullary spinal cord neoplasms. Results of the ultrasound exams were correlated with preoperative imaging studies, surgical findings, and histopathologic analysis of the tumors. Intraoperative spinal sonography accurately localized the intramedullary tumors, often revealing the need for extension of the initial laminectomy. The neoplasms appeared as expansile echogenic masses, with cystic components in over half. Ultrasound was as accurate as preoperative imaging in the evaluation of solid neoplasms, and was superior to computed tomography (CT) and magnetic resonance imaging (MRI) for delineating the cystic components of neoplasms. Intraoperative sonography should be used routinely in all surgical cases of intramedullary spinal cord neoplasms.

Adolescent↗
PubMed1987

The accuracy of CT in the staging of carcinoma of the prostate.

Previous studies have reported the accuracy of CT in distinguishing stages of prostatic carcinoma, but they lack uniform surgical proof of histopathologic stage. We evaluated CT scans in 32 patients who underwent radical prostatectomy to assess its role in the preoperative staging of prostatic carcinoma. Two experienced radiologists blindly interpreted CT scans of the pelvis; they looked for evidence of tumor beyond the prostatic capsule and involvement of the seminal vesicles (stage C) or involvement of pelvic lymph nodes (stage D). Sixty-four interpretations in 32 patients yielded a specificity of 75% for predicting stages A or B disease (local disease), a sensitivity of 50% for the prediction of stages C or D, and an overall accuracy of staging of 67%. Interpretation errors were due to an inability to detect lymph node metastases, errors in evaluating the seminal vesicles, and errors in interpreting densities surrounding the prostate gland. Our data suggest that CT should not be used to influence decisions concerning surgical vs nonsurgical treatment in patients with clinically staged local disease and is only useful when unsuspected metastatic nodal disease is detected.

Diagnostic Errors↗