Laurence Needleman

Pressure dependence of subharmonic signals from contrast microbubbles.

Noninvasive pressure estimation in heart cavities and in major vessels would provide clinicians with a valuable tool for assessing patients with heart and vascular diseases. Some microbubble-based ultrasound contrast agents are particularly well suited for pressure measurements because their substantial compressibility enables microbubbles to vary significantly in size in response to changes in pressure. Pressure changes should then affect reflectivity of microbubbles after intravenous injection of a contrast agent. This has been demonstrated with a galactose-based contrast agent using 2.0-MHz ultrasound tone bursts. Preliminary results indicate that, over the pressure range of 0-186 mmHg, the subharmonic amplitude of scattered signals decreases by as much as 10 dB under optimal acoustic settings and the first and second harmonic amplitudes decrease by less than 3 dB. An excellent correlation between the subharmonic amplitude and the hydrostatic pressure suggests that the subharmonic signal may be utilized for noninvasive detection of pressure changes.

Clinical applications of ultrasound contrast agents

Within the last decade safe and practical ultrasound contrast agents have been introduced. Most of these are based on gas-filled microbubbles, which markedly enhance Doppler signals and, in some cases, also gray-scale images. The clinical improvements expected from ultrasound contrast is reviewed. Tissue-specific contrast agents constitute another area of potential clinical significance. One particular agent is taken up by the reticulo-endothelial system and produces so-called acoustic emission signals when imaged. An introduction to the unique clinical applications of acoustic emission is given. Harmonic imaging is a new contrast-specific imaging modality, which utilizes the nonlinear properties of some agents in an attempt to alleviate current limitations of ultrasound contrast studies. Examples of harmonic images are presented.

CT-pathologic correlation of axillary lymph nodes in breast carcinoma

A prospective study was performed to determine whether thoracic CT yielded useful information regarding the status of axillary lymph nodes (LNs) in patients with breast cancer. Thirty-five consecutive patients with clinically suspected stage II or III breast carcinomas were scanned preoperatively from the supraclavicular regions to the lung bases. Axillary LNs measuring greater than or equal to 1 cm were considered abnormal. The lymph nodes were classified according to their relationship to the pectoralis muscle. Extracapsular lymph node extension was diagnosed when there was irregularity and spiculation of the lymph node margin with surrounding fatty infiltration. Correlation with axillary dissection was obtained in 20 patients, giving a positive predictive value for axillary metastases of 89% with 50% sensitivity, 75% specificity, and 20% negative predictive value. CT was also able to detect the level of axillary involvement accurately when the lymph nodes were enlarged and to evaluate extracapsular LN extension. Although superior to physical examination, CT was not an accurate predictor of axillary LN involvement, primarily because of its low negative predictive value.

Treatment of iatrogenic femoral artery injuries with ultrasound-guided compression

Iatrogenic injuries of the groin are becoming more common after increasingly sophisticated vascular intervention. These injuries are accurately detected by duplex and color Doppler ultrasonography. Recent treatment of these lesions by ultrasound-guided compression repair (UGCR) has been described. During a 1-year period we identified 18 femoral artery injuries, including 17 pseudoaneurysms and one arteriovenous fistula. Three of the pseudoaneurysms thrombosed spontaneously before attempted treatment. The remaining 15 lesions underwent a trial of UGCR. Successful closure was accomplished in 10 patients (56%). Seven of these lesions were successfully treated during the initial session, and thrombosis was accomplished after repeat compression in three additional lesions. Three patients who were given anticoagulants had a failed UGCR, but their pseudoaneurysms thrombosed after administration of anticoagulants was discontinued. Two patients had failed UGCR and required operation. Seven (88%) of eight patients who were not given anticoagulants were successfully treated. In contrast only two (29%) of seven patients given therapeutic doses of anticoagulant medication were successfully treated by the technique. There was no statistical difference between mean pseudoaneurysm diameter, mean width and length of pseudoaneurysm neck, or depth of pseudoaneurysm neck from skin surface in patients in whom successful initial closure was achieved when compared with those patients in whom the initial attempt failed. UGCR is a safe, simple, noninvasive technique that can be used to treat many femoral artery injuries that traditionally were treated with surgery. The technique can be applied by any laboratory that has the necessary ultrasonography equipment and is currently the method of choice for treating uncomplicated iatrogenic femoral artery injuries at our institution.

Feasibility of Performing a Virtual Patient Examination Using Three-dimensional Ultrasonographic Data Acquired at Remote Locations

To evaluate the feasibility of performing three‐dimensional ultrasonographic studies that meet American Institute of Ultrasound in Medicine and American College of Radiology ultrasonographic examination guidelines with review off‐line and at remote locations.

Breast tumor vascularity identified by contrast enhanced ultrasound and pathology: initial results

Quantifiable measures of vascularity obtained from contrast enhanced color flow images were correlated with pathologic vascularity measurements in ten female patients with a solid breast mass. Each patient received Levovist Injection (Berlex Laboratories Inc., Montville, NJ). Color flow images pre- and post-contrast were obtained using an HDI 3000 unit (ATL, Bothell, WA) before removing the mass for pathologic vascularity assessments. Image-processing techniques were used to obtain both the ultrasound and pathologic vascularity measurements. Multiple linear regression found significant correlations for ultrasonic vascularity measurements post contrast and pathology (P = 0.02 and 0.06). No correlations were found between pre-contrast ultrasound and pathology. In conclusion, post-contrast ultrasonic flow measures provide a non-invasive measure of breast tumor neovascularity. However, the patient population is small, and until further patients are analyzed, these conclusions are preliminary.

The role of preoperative radial artery ultrasound and digital plethysmography prior to coronary artery bypass grafting

OBJECTIVE Doppler ultrasound and digital plethysmography are used at our institution to determine the suitability of the radial artery for harvest prior to coronary artery bypass grafting (CABG). The purpose of this study is to determine the value of this preoperative evaluation. METHODS A retrospective analysis of non-invasive radial artery testing was performed on 187 CABG patients. Criteria used to exclude radial arteries from harvest were anatomic abnormalities (size<2 mm, diffuse calcifications), and perfusion deficits during radial artery occlusion (>40% reduction in digital pressure, non-reversal of radial artery flow, or minimal increase in ulnar velocity). A questionnaire was used to determine the incidence of postoperative hand ischemia or rehabilitation. RESULTS In 187 patients, 346 arms were evaluated. Ninety-four arms (27.1%) were excluded for harvesting. Anatomical abnormalities included size<2 mm (1.5%), diffuse calcifications (8.7%), congenital anomalies (2.3%), and radial artery occlusion (0.3%). Circulatory abnormalities included non-reversal of flow (7.2%), abnormal digital pressures (5.5%), and inappropriate increase in ulnar velocity (1.7%). A total of 116 radial arteries were harvested. There were no episodes of hand ischemia. No patient required hand rehabilitation. CONCLUSIONS Doppler ultrasound and digital plethysmography identifies both perfusion (14.5%) and anatomical (12.7%) abnormalities that may make the radial artery less suitable as a bypass conduit.

Detection of retained products of conception following spontaneous abortion in the first trimester.

A retrospective analysis was performed to determine whether ultrasound could reliably rule in or out retained products of conception (POC) in women after first‐trimester spontaneous abortions (miscarriages). Ninety‐seven first‐trimester pregnancies with pathologically proven results from dilatation and curettage (D&C) were studied within 7 days of ultrasound examination (60% within 2 days), either by the abdominal or a combination of abdominal and vaginal approaches. Cases were eliminated if there was clinical evidence of a spontaneous evacuation of POC during the interval between the ultrasound and the D&C. POC were diagnosed only if chorionic villi were evident pathologically. The pertinent ultrasound findings were related to the endometrium (thickness, echogenicity, a gestational saclike structure or a space‐occupying collection). The results indicated that ultrasound could correctly diagnose POC in all of the cases by detecting a gestational sac or collection (77 cases), or a thickened endometrium of greater than 5 mm (6 cases). Ultrasound was less reliable in ruling out retained POC. When only a thin endometrial stripe of less than 2 mm was present, there was little likelihood of having POC (1 of 7 cases) with a moderately thick endometrium of 2 to 5 mm not diagnostic. Vaginal ultrasound added little new information and failed to change the ultrasound interpretation.

Prospective comparison of vaginal and abdominal sonography in normal early pregnancy.

Vaginal and abdominal sonography were prospectively compared in 309 consecutive pregnancies of which 175 were normal. Two sonographic criteria of normal were analyzed: (1) the presence of an embryo compared with average gestational sac size and (2) the presence of embryonic cardiac activity compared with crown‐rump length. Vaginally, 100% (160/160) of embryos were visualized when the average sac diameter was greater than or equal to 12 mm. Abdominally, an embryo was noted in 99.2% (123/124) of gestational sacs greater than or equal to 27 mm. Vaginal sonography revealed cardiac motion in all embryos of greater than or equal to 5 mm (149/149 cases); abdominal sonography revealed cardiac activity in 100% (132/132) of embryos with a crown‐rump length of greater than or equal to 9 mm. One‐third of normal embryos less than 5 mm crown‐rump length did not demonstrate cardiac activity. The study demonstrates through objective comparison that vaginal sonography is superior to abdominal sonography for detection of an intrauterine embryo and its cardiac activity before 8 menstrual weeks. The diagnosis of embryonic demise should not be made by vaginal sonography in embryos measuring less than 5 mm crown‐rump length without a heartbeat, and an empty gestational sac of less than 12 mm average diameter should not be diagnosed as blighted ovum by vaginal scans. In these cases follow‐up vaginal sonography is suggested.

Diagnosing Breast Lesions With Contrast-Enhanced 3-Dimensional Power Doppler Imaging

Objective. To compare mammography with contrast‐enhanced 2‐ and 3‐dimensional power Doppler imaging for the diagnosis of breast cancer. Methods. Fifty‐five patients, who underwent breast biopsies with histopathologic assessment, participated in a study of mammography and contrast‐enhanced sonography. Levovist (Berlex Laboratories, Montville, NJ) and Optison (Mallinckrodt, St Louis, MO) were administrated to 22 and 33 patients, respectively. Precontrast and postcontrast 2‐dimensional power Doppler data of the lesion were obtained with an HDI 3000 system (Philips Medical Systems, Bothell, WA), and 3‐dimensional data were acquired with an LIS 6000A system (Life Imaging Systems Inc, London, Ontario, Canada). Two independent and blinded readers assessed diagnosis. Receiver operating characteristic curves were computed individually and in combination for mammography and 2‐ and 3‐dimensional sonography (before and after contrast). Histopathologic and imaging parameters were compared by Mann‐Whitney statistics. Results. Mammographic findings were available for 50 patients, biopsy for 54, and 2‐ and 3‐dimensional sonographic images for 53 and 52, respectively. Of the 50 patients who had all 4 measures, 15 (30%) had malignancies. The areas under the receiver operating characteristic curve for the diagnosis of breast cancer were 0.51 for 2‐dimensional contrast‐enhanced imaging, 0.60 for 3‐dimensional power Doppler imaging, and 0.76 for 3‐dimensional contrast‐enhanced imaging (P < .01). Mammography produced an area of 0.86, which increased when combined with 3‐dimensional contrast‐enhanced imaging to 0.90 and with all sonographic modalities to 0.96 (P < .001). The histopathologic diagnosis of benign or malignant correlated with the presence or absence of anastomoses and with the degree of vascularity assessed with contrast‐enhanced 3‐dimensional power Doppler imaging (P = .007 and .02). Conclusions. Contrast‐enhanced 3‐dimensional power Doppler imaging increases the ability to diagnose breast cancer relative to conventional 2‐ and 3‐dimensional sonographic imaging.