Biomedical subjects
Publications and source records attributed to M D Rifkin.
This article reviews the type of equipment used in sonography of the tendons, the method of approach in viewing normal tendon anatomy, and the sonographic appearance in pathologic conditions of the tendons. The role of ultrasound in follow-up studies is also emphasized because of its noninvasive nature.
Eight patients with suspected diagnosis of distal radioulnar joint (DRUJ) subluxation underwent computed tomographic (CT) scans of the wrist. Five underwent surgery and had DRUJ subluxation or dislocation; CT scans revealed subluxation in four. Three CT criteria for the evaluation of DRUJ subluxation are discussed and compared in this manuscript.
Since its development in the late 1970s, scrotal ultrasound has been used successfully to diagnose and evaluate many pathologic processes. At present, except for evaluation of a few entities, it is the diagnostic imaging modality of choice. Differentiation of normal from abnormal scrotal contents is possible with great accuracy. The technique is capable of differentiating cystic from solid lesions and testicular from extratesticular disease with an accuracy approaching 100%. It has also been used successfully for evaluation of some causes of male infertility and various congenital abnormalities. Evaluation of spermatic cord torsion and undescended testes is generally better done with other techniques. Scrotal ultrasound, however, is still used as a complementary, but not the primary, study for these diagnoses.
A thirty-two-year-old man presented with a history of infertility, recurrent epididymitis, and a fluctuant pelvic mass on rectal examination. Preoperative evaluation disclosed a nonvisualized right kidney and a multiloculated cystic lesion in the pelvis. The intravenous pyelogram suggested a ureterocele on the right side. A cystic pelvic mass was noted on ultrasound and computed tomography. A dysplastic right kidney with an ectopic ureter inserting into a cystic seminal vesicle was found at surgical exploration.
Forty-nine patients operated on for liver or other pathologic processes were examined intraoperatively with special ultrasound transducers during surgical exploration of the abdomen. Subjects were evaluated because of known or suspected disease of the liver. All patients were examined using sterile technique. Prospective diagnosis and retrospective analysis of data were used. In 55% of subjects, no new information was obtained. In 19%, new information was gathered that changed the surgical approach. In 14% of patients, new information was obtained but it was such that no change in the therapeutic approach was needed. In 12% of patients, although no new information was gathered by the use of intraoperative ultrasound, a change in the surgical approach and management of the patient was still possible because of intraoperative ultrasound. These studies show that the routine use of ultrasound during intraoperative procedures, particularly when involving hepatic structures, is a clinically useful technique. In many instances, it will change the course of management.
Endovaginal ultrasound (US) was performed in 38 pregnant women at 5-12 menstrual weeks, when the initial transabdominal sonograms had been considered inconclusive or equivocal. Clinical follow-up disclosed 32 intrauterine pregnancies (12 living, 18 spontaneous incomplete abortions, and two embryonic demises) and six ectopic pregnancies. In the 32 intrauterine pregnancies (normal and abnormal), the correct diagnosis was made in all cases with endovaginal US. The endovaginal images demonstrated the intrauterine embryo, its heart motion, and the yolk sac more clearly and more often when these structures were not apparent on the transabdominal scans. Abnormal gestational sacs were better resolved. In the six cases of ectopic pregnancy, while an extrauterine ectopic sac was visualized in only three, absence of an intrauterine gestational sac was confirmed in all cases with endovaginal scanning. No endovaginal study yielded less information than its transabdominal counterpart. Endovaginal sonography is likely to be diagnostic when transabdominal images fail to yield a definitive diagnosis in early pregnancies.
Three patients with clinically suspected pseudoaneurysm as a complication of femoral puncture were referred for ultrasound (US) evaluation with both conventional duplex Doppler US and color Doppler imaging. Pseudoaneurysm (n = 2) and simple hematoma (n = 2) were depicted with both Doppler systems, and a separate pseudoaneurysm and a hematoma were found in one patient. These diagnoses were confirmed surgically. Distinctive Doppler spectral waveforms and color Doppler findings enabled confident diagnoses. Color Doppler imaging allowed faster detection of intraaneurysmal flow, and the track between the injured artery and the pseudoaneurysm was identified only with color Doppler imaging. Duplex Doppler US with color Doppler imaging allows for the rapid, unequivocal diagnosis of pseudoaneurysm, thus enabling prompt treatment without the need for invasive diagnostic modalities.
A retrospective study of 55 twin pregnancies was performed to determine the role of sonography in distinguishing between dichorionic and monochorionic diamniotic gestations solely by evaluating the thickness of the membrane between the fetuses. The presence of a thick dividing membrane indicated a dichorionic diamniotic gestation in 38 (90%) of 42 cases in which it was identified. Inability to identify a membrane between dichorionic diamniotic twins occurred most commonly during the third trimester. A thin membrane indicated monochorionic diamniotic twinning and was seen in three (25%) of 12 cases. Membrane thickness was indeterminate in one case. Therefore, on the basis of the thickness of the dividing membrane imaged by sonography, dichorionic diamniotic gestations can be distinguished from monochorionic diamniotic gestations. Inability to show a separating membrane by sonography, however, can occur with any form of twin gestation, particularly in the third trimester. Membrane thickness should be used in conjunction with other sonographic criteria to predict the amnionicity and chorionicity of twin gestations.
The increasing use and availability of renal transplantation has resulted in a demand for noninvasive methods to study possible complications. One of the most serious adverse reactions is acute rejection, a possibly reversible cause of transplant failure if treated promptly. Differentiation from other causes of acute renal failure frequently is difficult, and the lack of specificity in many imaging studies has been troublesome. Eighty-one patients with renal transplants, including 41 with acute rejection, were examined. Duplex Doppler examination of the intrarenal arteries and a simplified formula, the resistive index ([peak systolic frequency shift--lowest diastolic frequency shift]/[peak systolic frequency shift]), were used to diagnose rejection. With a resistive index greater than 0.90, a 100% positive predictive value was obtained for the diagnosis of acute rejection. A value less than 0.70 was unlikely to be rejection (negative predictive value, 94%). This approach uses a simple analysis of the waveform. Use of a duplex Doppler examination and the formula described here appears to be an accurate method for the detection of acute rejection and for the differentiation of acute rejection from the various other causes of acute renal failure.
The sonograms of 76 hemorrhagic ovarian cysts were reviewed to ascertain the full spectrum of sonographic findings. All cases were proved either by surgery or by documented resolution on sonography and/or clinical follow-up. The overwhelming majority (92%) had increased sound through-transmission, signifying the basic cystic nature of the lesion. The sonographic patterns were variable. The most common appearance was that of a heterogeneous mass (83%), almost half of which were predominantly anechoic with hypoechoic material. The other cases (17%) were completely homogeneous, either hypo- or hyperechoic. No masses were completely anechoic. Additional sonographic features included a thick rim, septations, and associated cul-de-sac fluid. A rounded hyperechoic mass, representing blood clot, was contained within 13 masses. In addition, some women appeared to have an increased tendency to form ovarian cysts, suggested by the fact that 26% of them had a past, concurrent, or future episode of simple or hemorrhagic ovarian cysts. Because hemorrhagic ovarian cysts have variable sonographic findings, they should be included in the differential diagnosis of any adnexal mass that has good sound through-transmission.
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So that radiologists can understand better the differences between tissues that determine MR image contrast, the biophysical basis of proton-MR tissue contrast is reviewed. Differences in the molecular sizes of water, fat, and protein macromolecules affect the rate of molecular motion, which in turn influences relaxation times. Differences in the physical state of water within tissues determine the extent to which the motion of water is restricted by binding to hydrophilic macromolecules (e.g., protein), which in turn causes variable amounts of T1 and T2 shortening. Understanding these concepts and knowing the location in the body of free water, cellular tissues, fat, collagen, bone, and tissue iron improve the radiologist's ability to extract useful information from MR images.
The evaluation of pelvic masses is routinely performed by transabdominal ultrasound. However, by placing the transducer into the vagina (the endovaginal approach), imaging resolution is improved and morphologic detail of true pelvic organs is increased. Twenty-one cases in which nonobstetrical pelvic pathology was suspected clinically were evaluated by both the endovaginal and (conventional) transabdominal approach. Each case was evaluated for efficacy of the two approaches independently and the results compared to the clinical outcome. Endovaginal scanning offered more accurate diagnostic information in 13 of the 21 cases (62%). Additional information was obtained by the endovaginal approach in seven of these 13 cases (55%). No significant difference was observed in 33%. Endovaginal ultrasound offers a diagnostic tool complementary to the transabdominal technique in the evaluation of pelvic masses in the female patient.
Sonographic abnormalities secondary to postasphyxial encephalopathy in neonates are reviewed. This report emphasizes an additional finding, increased echogenicity of the thalamus and basal ganglia, demonstrated in four term infants. This abnormal finding is generally noted in the second week following asphyxia. In some cases, the increased thalamic echogenicity may be a temporary finding. A representative case is described and possible pathologic correlates are discussed.
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Endorectal ultrasound was used prospectively to stage 85 patients with rectal cancer. All patients had surgical exploration and histological analysis. Demonstration of tumour, extension into perirectal fat and lymph node involvement were evaluated. Eighty-one tumours were successfully imaged by endorectal ultrasound. The results suggest that: endorectal ultrasound is more accurate than CT in detecting the site of tumour; endorectal ultrasound is more accurate than CT in detecting perirectal fat infiltration; endorectal ultrasound is slightly more accurate than CT in detecting level II lymph node involvement.
An end-viewing fiberoptic gastroscope was modified to incorporate a high-resolution linear array real-time ultrasound transducer 7 cm proximal to the flexible tip of the instrument. This endoscope was used to evaluate 20 patients suspected of having mural disease of the upper gastrointestinal tract and five normal subjects. The endosonographic examination defined esophageal, stomach, and duodenal wall thickness in normal subjects. In patients with pathological findings, both diffuse and acoustically focal lesions were demonstrated, and the extent of these lesions were outlined. With focal masses, endosonographic findings also demonstrated echogenic differences between various submucosal tumors reflecting their differing etiology. The extent of invasion and adenopathy were identified in a patient with gastric carcinoma. With diffuse lesions, the depth of involvement could be outlined sonographically, but etiologic diagnosis depended on biopsy. Extrinsic masses with secondary invasion of the wall of the upper gastrointestinal tract were defined in six patients. It is suggested that endosonography may prove to be a useful technique for evaluation of mural, invasive extramural, and diffuse lesions of the upper gastrointestinal tract.