Second-trimester placental volumes predict birth weight at term.

OBJECTIVE: To test the hypothesis that second-trimester placental growth is a major determinant of size at birth in healthy, active women. METHODS: Three serial measurements of fetal morphometry and placental volume were obtained between the 14th and 26th weeks of an accurately dated singleton pregnancy in 40 subjects. RESULTS: Second-trimester placental volumes were variable, increasing from (mean +/- standard deviation) 130 +/- 35 to 248 +/- 67 and to 375 +/- 92 cm3 at 16, 20, and 24 weeks, with an average growth rate of 31 +/- 8 cm3/weeks. At delivery, fresh placental volumes and birth weights were also variable, ranging between 304-823 cm3 and 2.6-4.4 kg, respectively. Significant correlations (r > 0.79) were present between second-trimester placental volume or growth rate and placental volume at delivery and birth weight, corrected for gestational age and infant sex. However, correlations between second-trimester fetal biometry and both corrected birth weight and birth weight percentile were poor (r < 0.45). CONCLUSION: Second-trimester placental volumes and growth rates are good predictors of size at birth in healthy, active women. We speculate that this technique may have real value as an early screening tool to identify cases at risk of anomalous third-trimester growth.

Hyperlucent thorax from rotation. Anatomic basis.

RATIONALE AND OBJECTIVES: The authors studied a large group of patients with a computed tomography (CT)-based model to evaluate the presence, significance, and anatomic basis of unilateral hyperlucency from patient rotation. METHODS: Chest CT sections at three levels in 65 consecutive patients undergoing routine diagnostic studies were read into a microcomputer. Radiographic transmittance data were calculated across each CT section at different degrees of rotation as well as for lateral decentering. Data were analyzed for the pattern of density variation both individually as well as in stratified subgroups. RESULTS: The data showed a trend of increasing radiographic transmission on the side opposite that of the anterior obliquity. The resulting optical density difference was small and was not clinically significant. Lateral decentering produced smaller changes than rotation. The anterior breast/pectoral structures are the etiology for the phenomenon. Optical density differences of 0.1 result from a difference in tissue thickness of 4 mm. CONCLUSIONS: The changes in radiographic transmission with rotation are small and are overshadowed by soft tissue compression. Rotation alone will result in decreased radiographic transmission on the side of anterior obliquity; thus, the left side will be more lucent in an right anterior oblique projection.

Traumatic aortic injuries: current concepts.

This article summarizes current concepts of traumatic injuries of the aorta. The "osseous pinch" mechanism of injury is presented and discussed. The role of each imaging modality in patient evaluation is considered and a rational approach to their use suggested based on current technology and practices.

Rounded atelectasis and fibrotic pleural disease: the pathologic continuum.

Although rounded atelectasis was recognized in 1928, its relationship to fibrotic pleural disease almost has gone unnoticed. We present four cases of lobar rounded atelectasis that help to clarify this relationship. Rounded atelectasis is part of the spectrum of fibrous pleural disease. Any portion of lung may become entrapped by the pleural process. When focal areas are involved rounded atelectasis results. When a larger portion of the thorax is involved with this process, lobar rounded atelectasis may occur. Very extensive disease is recognized as fibrothorax.

Gastroschisis: prenatal CT diagnosis.

The prenatal sonographic findings of gastroschisis are well defined. This report describes the CT appearance of fetal gastroschisis discovered as an incidental finding when a 25-year-old pregnant woman underwent CT for blunt abdominal trauma.

Traumatic lacerations of the aorta and great vessels with a normal mediastinum at radiography.

The possibility of a "normal" mediastinum at conventional chest radiography in a patient with a lacerated aorta or great vessel from blunt thoracic trauma has not been evaluated objectively. All 1991 members of the Society of Thoracic Radiology were sent a questionnaire asking for examples of such cases. A similar questionnaire was placed in the newsletter of the Society of Cardiovascular and Interventional Radiology. The literature also was reviewed for cases. Seventy-eight of 327 questionnaires were returned with responses. Eight responders reported 12 examples of a normal mediastinum radiograph in a patient with a lacerated aorta. Review of the same radiographs by the authors yielded three normal and nine subtly abnormal mediastina. One additional normal radiograph was obtained of a patient with a lacerated great vessel. Another 16 cases of lacerated aortae (n = 12) and great vessels (n = 4) in patients with normal mediastina were found through a literature search; images from three of these were reviewed by the authors. Although this is an infrequent event, the mediastinum can be normal at plain chest radiography with traumatic lacerations of the aorta and great vessels.

CT evidence for the "osseous pinch" mechanism of traumatic aortic injury.

OBJECTIVE: Our prior experiments suggested that traumatic laceration of the aorta induced by rapid deceleration results from pinching of the aorta between the spine and the anterior bony complex (manubrium, clavicle, and first rib). This study examines that hypothesis with in vivo CT data. MATERIALS AND METHODS: In 22 patients with angiographically and surgically proved lacerations of the proximal descending aorta, chest CT scans were obtained before (18) or after (four) surgical repair. The point of impact of the anterior bony complex with the anterior surface of the thoracic spine during compression of the thorax was predicted by simulated rotation of the first rib based on calculations made from the CT scans. RESULTS: In all 22 patients, the projected site of impact of the anterior bony complex with the spine corresponded to the actual injured aortic segment as determined with angiography. CONCLUSION: Our data further support the proposed "osseous pinch" mechanism of injury to explain traumatic tears of the aorta.

Radiological application of three-dimensional imaging systems.

Three-dimensional displays are becoming more frequent in medical imaging. As PACS and imaging workstations as nodes on networks provide greater ease and availability of three-dimensional reconstructions of digital data applications are increasing. Applications at this time are limited to high-contrast structures. In CT these are complex fractures or deformities. Three-dimensional display clarifies the anatomy and facilitates operative planning. In MRI, MR angiography is the principal application. The ability to rotate the data set in three dimensions eliminates potential overlap, increasing the sensitivity and specificity of the technique. Three-dimensional imaging is becoming available for scintigraphic and sonographic studies but applications have not yet been clarified.

Improvement in CT pelvimetry.

When computed tomographic (CT) digital radiography is used for pelvimetry, measurement error may occur. Geometric distortion in the lateral direction of the CT digital radiograph can lead to an error in any measurement of the transverse pelvic inlet. The authors measured the magnitude of this error on two scanners and present a general method for correction of this potential error. The authors also showed that an additional dose reduction is possible if the patient is imaged in the posteroanterior rather than anteroposterior projection.

A proposed new mechanism of traumatic aortic rupture: the osseous pinch.

The currently accepted mechanism to explain traumatic aortic rupture from rapid deceleration involves a combination of traction, torsion, and hydrostatic forces. The authors hypothesize that aortic isthmus lacerations result from a pinch of the aorta between the spine and the anterior bony thorax (manubrium, clavicle, and first ribs) during chest compression caused by abrupt deceleration. Compression of an articulated, normally moving thoracic skeleton containing a synthetic aorta consistently caused transection of the aorta at the isthmus between the spine and anterior bony structures. Analysis of rotation of the first rib in 10 consecutive patients undergoing computed tomography of the chest demonstrated interposition of the distal aortic arch and isthmus between the vertebrae and anterior bony thorax in each instance. Aortas excised from laboratory dogs were pinched between structures simulating bones to reproduce intimal and medial lesions indistinguishable from lesions associated with naturally occurring traumatic disruptions. Although further studies in cadaveric specimens are necessary to confirm this mechanism of injury, the authors believe that their results support the osseous-pinch mechanism of aortic rupture.

Correlation of Fourier spectral shift-determined hepatic acoustic attenuation coefficients with liver biopsy findings.

We calculated hepatic acoustic attenuation coefficients (ACs) in 13 patients who had liver biopsies and in 3 normal subjects by means of Fourier spectral analysis of reflected ultrasound signals from increasing depths in the liver. The ACs were correlated with estimated percentage area occupied by fat in the liver biopsies; linear regression analysis revealed a correlation coefficient of r = .78 (p less than .001). The presence of fibrosis did not correlate with AC.

Technetium-99m sulfur colloid spleen imaging following partial pancreatectomy and splenic artery and vein resection.

We retrospectively studied the records and [99mTc]sulfur colloid (TSC) spleen studies of 38 patients who underwent distal pancreatectomy with splenic artery and vein resection for donation to HLA-compatible relatives. The spleens in immediate postoperative TSC studies were normal in 11% of cases, showed no uptake in 16%, showed diffusely decreased uptake in 50%, and showed focal defects in 26%. Twenty of the patients, all with abnormal initial TSC studies, had repeat studies 2 wk to 3 yr later; 15% showed no change, 35% showed some improvement, and 45% became normal. One of six patients with no TSC uptake required splenectomy 2 days after pancreatectomy for splenic infarction. These data suggest that the spleen usually survives splenic artery and vein resection. Absent splenic TSC uptake raises the possibility of splenic infarction.

Clinical efficacy of Kitecko ultrasonic conductor.

A homogeneous synthetic polymer block (Kitecko) was evaluated for ultrasound imaging of small parts, superficial structures, and the pediatric patient. The block is intended to be used as an offset and replaces the traditional way of scanning with water paths, fluid-filled surgical gloves or IV bags. A randomized paired comparison of the Kitecko pad conductor and a water path system (IV bag) was performed. One hundred pediatric and adult patients were scanned using both conductors. The images were encoded and subsequently evaluated for image quality, including artifact, attenuation, resolution, and distortion. A statistical analysis showed significantly higher scores (P less than .01) with the Kitecko substance when compared to water path scanning when evaluating for reverberation artifact, scatter artifact, and spatial resolution.

Gantry tilt technique for CT-guided biopsy and drainage.

An angled approach to percutaneous biopsy or drainage using CT guidance is often required to avoid transgressing vital intervening structures. We describe a simple technique for CT-guided angled biopsy. By tilting the CT gantry off the axial plane, CT scans can be obtained that directly demonstrate the appropriate angle of approach while avoiding intervening structures. The gantry tilt technique provides direct visualization of the pathway of the needle tract; direct visualization is not possible with previously described techniques such as stereotactic biopsy or the triangulation technique. The gantry tilt technique is a practical, simple means for performing angled CT biopsy or aspiration in many cases.

Clinical significance of sonographic findings in the abnormal but intact rotator cuff: a preliminary report.

Shoulder pain is a common orthopedic problem. Clinical examination is often nonspecific and arthrography is normal in those patients with the most frequent cause of shoulder pain--noncalcific tendonitis secondary to impingement. Ultrasonography has recently shown itself to be of value in the diagnosis of rotator cuff tears. In addition to the diagnosis of tears, however, sonography can demonstrate abnormalities within the intact rotator cuff tendon. These abnormalities consist of changes in echogenicity and thickness of the tendon. The patterns of abnormality demonstrated correlate with pathologic changes seen in tendonitis. This preliminary study suggests that the ability to demonstrate an abnormal rotator cuff tendon has potential for becoming a valuable aid to the orthopedist in allowing confident diagnosis of rotator cuff disease in the presence of nonspecific symptomatology and an intact tendon.

Ultrasonography of rotator cuff tears: a review of 500 diagnostic studies.

Ultrasonography of the rotator cuff has been shown to be of value in diagnosing rotator cuff tears. This report summarizes our experience with our first 500 diagnostic examinations. All patients were examined in the hyperextended internal rotation view with commercially available high-resolution real-time ultrasound equipment. Patients were diagnosed as having a rotator cuff tear if a focal echogenic lesion or a defect within the rotator cuff was identified. This study confirmed the value of ultrasonography for the diagnosis of rotator cuff tears. Accuracy, sensitivity, and specificity all exceeded 90%, and correlated with surgical findings. This was better than arthrography in the same patient population. Ultrasound is an accurate noninvasive method of examining the rotator cuff for the presence of tears. We suggest that rotator cuff ultrasonography is the procedure of choice for the diagnosis of tears if adequate instrumentation is available.

Tendon echogenicity: ex vivo study.

Recent publications discussing the echogenicity of normal tendon have described it variously as hyperechoic or hypoechoic. Since the echogenicity of tendon has been used to define normality and abnormality, certain knowledge of the normal echogenicity of tendon is crucial. Fresh tendon and muscle from beef hock was scanned with sector- and linear-array-transducer imaging at multiple angles and distances. The echogenicity of tendon was found to be very angle-dependent, a characteristic known as anisotropy. Scanned perpendicular to its long axis with a linear-array transducer, tendon was significantly more echogenic than muscle. With a change in angle, echogenicity of tendon decreased relative to that of muscle (the echogenicity of muscle remained the same), becoming isoechoic at angles of 2 degrees -7 degrees and hypoechoic at greater angles. Tendon studied with a sector transducer exhibited varying echogenicity. If echogenicity is used as a diagnostic criterion, the angle of the interrogating ultrasound beam must be very specifically defined.