Computed tomography appearance of a right cervical aortic arch.

The clinical diagnosis of cervical aortic arch rests on the detection of a pulsatile mass in the supraclavicular fossa. Unfortunately, clinical differentiation of a cervical arch from an aneurysm of the great vessels can be difficult. Dynamic computed tomography (CT) can aid in this differentiation and avert the need for angiography.

Enhanced pancreatic CT imaging utilizing a geometric magnification technique.

Computed tomography (CT) using a geometric magnification technique was found to improve spatial resolution in phantom studies when compared with conventional third-generation geometry images. The clinical feasibility of using geometric magnification, small focal spot size, and dynamic contrast enhancement was studied in 143 patients referred to CT for clinically suspected pancreatic disease. This population included 46 patients with a normal pancreas and 36 patients subsequently proven to have primary pancreatic carcinoma. Using this new technique in conjunction with dynamic contrast enhancement resulted in high quality pancreatic images. Despite the limitations in tube current associated with a small focal spot size and low total heat capacity of the system, clinical imaging was not adversely affected. Use of the geometric magnification technique is recommended in departments where it is technically feasible.

Follicular aspiration: a comparison of an ultrasonic endovaginal transducer with fixed needle guide and other retrieval methods.

Ultrasonic techniques have been developed as alternatives to conventional laparoscopic aspiration for oocyte retrieval for in vitro fertilization (IVF). Given the advantages (less risk, lower cost, and greater patient acceptance) of these alternative techniques, it is appropriate to assess their efficacy compared with traditional laparoscopic retrieval. This article examines the recovery rate of oocytes and their subsequent fertilization rate with the use of an ultrasonic endovaginal transducer with fixed needle guide and compares these results with other retrieval methods. Comparisons were made between laparoscopic harvesting (n = 71, group I), ultrasonic transabdominal transvesical (n = 21, group II), and ultrasonic vaginal transducer (n = 76, group III). The data demonstrate comparable success using an ultrasonic endovaginal transducer with fixed needle guide. The authors believe this technique to be the procedure of choice for all routine oocyte retrievals during IVF treatment.

Magnetic resonance. Principles and applications.

Magnetic resonance is a unique, noninvasive imaging modality which allows direct, multiplanar imaging and the possibility of obtaining biochemical information in vivo. Presently, MR appears most applicable to the evaluation of central nervous system abnormalities. The high sensitivity of MR in the evaluation of intracranial pathology suggests that it may eventually replace CT for many suspected diseases, if future investigations are able to improve its specificity. As previously noted, MR may be more diagnostic than other radiologic studies in the evaluation of suspected Chiari malformation, syringomyelia, congenital abnormalities, tumors of the spinal axis, and disc space infection. In the chest, MR appears to be more accurate than CT in the determination of the extent of mediastinal tumor, but at present cannot replace CT because of the lack of experience in imaging parenchymal nodules and benign diseases. MR of the breast is promising, but the size of the lesion may prove to be a limiting factor with magnetic field strengths commonly being utilized. There are inherent difficulties in the evaluation of cardiac disease with MR, but it offers a noninvasive method of investigating congenital heart disease and may provide valuable information in suspected myocardial ischemia and altered cardiac function. MR provides a new method of evaluating the vascular system, both in terms of providing anatomic information on large and medium-sized vessels and flow analysis. In the abdomen, MR appears to be most sensitive in the evaluation of suspected hepatic masses, but as with the brain, greater specificity will be needed to replace CT. At the present time, MR offers no distinct advantage over conventional imaging modalities in the evaluation of pancreatic disease, it maybe more accurate than CT in the staging of renal cell carcinoma. Larger studies are needed to determine the role of MR in the investigation of retroperitoneal adenopathy and adrenal abnormalities. In the pelvis, MR offers the hope of earlier diagnosis of prostatic carcinoma and may replace CT for staging of prostatic carcinoma and transitional cell carcinoma of the bladder. Limited MR experience with benign disease of the female pelvis suggests that it is currently more accurately evaluated with ultrasound. MR appears to be highly sensitive and specific for the diagnosis of avascular necrosis and may provide an early clue in suspected osteomyelitis. Finally, in vivo MR spectroscopy may provide unique metabolic information that was unobtainable prior to the advent of magnetic resonance, if this proves to be technically feasible.

Imaging of the liver, biliary tract, and pancreas.

The interaction between the various noninvasive and invasive imaging modalities used to evaluate the liver, biliary tract, and pancreas is demonstrated in this article. By understanding this interaction and correlating noninvasive studies, the clinician will avoid diagnostic redundancy and the need for invasive testing may be reduced.

Magnetic resonance imaging of the spine: applications and limitations.

MRI is a unique, noninvasive imaging modality that has already received wide application in the evaluation of abnormalities involving the spinal axis. It is the procedure of choice in the evaluation of suspected syringomyelia, Chiari malformation, and disk space infection. MRI is the only imaging modality presently capable of imaging multiple sclerosis plaques involving the spinal cord and is the only noninvasive modality that can diagnose nonherniated degenerated disks. MRI may provide valuable information in degenerative diseases of the spine, tumors of the spinal axis, and other congenital abnormalities, as either a primary or adjuvant imaging modality. Further investigation is needed to define the role of MRI in the evaluation of the traumatized and postoperative spine. Surface coil techniques hold promise in alleviating the present shortcomings of MRI, which are related primarily to slice thickness and attendant partial volume averaging. Chemical shift imaging may also be useful in accentuating subtle contrast differences between tissues and therefore highlighting abnormalities.

Imaging approach to the suspected renal mass.

The authors present their algorithmic approach to the detection, characterization, and staging of renal masses. Based on classification of urographic findings, the patient may be triaged to the appropriate cross-sectional or invasive imaging modality that will result in the most cost-effective management.

Hepatic imaging: current status.

The radiologist needs to be aware of the varied appearance of hepatic mass lesions and be prepared to recommend the most cost-effective imaging approach. In this article, the authors discuss their hepatic imaging experience, common pitfalls, and current recommendations.

Nuclear magnetic resonance of the spine: clinical potential and limitation.

Magnetic resonance can visualize the vertebral bodies, discs, neural structures, cerebrospinal fluid (CSF), neural foramina, and extradural structures in the sagittal, axial, and coronal planes. The normal nucleus pulposus can be differentiated from the anulus and changes associated with degeneration. Infection, trauma, and neoplastic conditions can be identified. The signal intensity of the CSF relative to extradural and neural structures can be increased to provide evaluation of the size and configuration of the contents of the thecal sac without the use of an intrathecal contrast medium. Impingement by disc, tumors, fracture segments, and expansile masses can then be accurately evaluated. It is the most accurate modality for the evaluation of the foramen magnum, Chiari malformation, syringomyelia, infection, and degeneration of intervertebral discs. It can identify paravertebral soft tissue and bony changes when plain films and computed tomographic (CT) studies are negative or equivocal. Not only can lesions be localized, but significant information regarding the nature of the process can be obtained. Using variations of the spin-echo technique with appropriate T1 and T2-weighted images, magnetic resonance can produce tissue contrast distinctions not possible with CT scans or conventional angiography.

Metastasis or adenoma? Computed tomographic evaluation of the adrenal mass.

BACKGROUND: Determining the nature of an adrenal mass is often a clinical challenge. OBJECTIVE: To determine if unenhanced computed tomographic (CT) scanning can differentiate benign adenomas from metastases. METHODS: Twenty-four pathologically proven adrenal masses were retrospectively correlated with their appearance on unenhanced CT scanning. RESULTS: Metastases were significantly larger than adenomas and had higher attenuation coefficients. A sensitivity-to-specificity ratio of 33:100 was achieved at a threshold of 0 Hounsfield units (HU), while a threshold of 10 HU produced a ratio of 58:92. A threshold size of 2.5 cm produced a ratio of 58:100. Attenuation and size were the only useful criteria for differentiating adenomas from metastases. CONCLUSION: Measuring the size and attenuation of adrenal masses can help identify benign adenomas. Lesions exceeding specific thresholds may still be benign and may require biopsy. We advocate documenting lesion stability for longer than is usually done, as one metastatic lesion remained without significant change in appearance for 18 months.

Doppler color imaging. Scrotum, breast, thyroid, and extremities.

DCI, when coupled with small-parts gray-scale imaging, has demonstrated great utility in the evaluation of superficial body abnormalities. This technique has rapidly become a primary method of evaluation of suspected testicular torsion, and its results are competitive with those of standard nuclear medicine examinations. DCI evaluation of male impotence, coupled with intracavernous injection of vasoactive substances, is now a leading, noninvasive technique for diagnosis of both arteriogenic and venogenic causes. DCI may provide invaluable information in the evaluation of palpable masses, particularly in the diagnosis of vascular abnormalities such as false aneurysm and arteriovenous fistula. Further studies are needed to corroborate the utility of DCI in the evaluation of focal thyroid and parathyroid abnormalities, breast carcinoma, nodal cancer, and the orbit. Because this technique is applicable to superficial, high-frequency examinations, DCI is rapidly becoming an accepted and frequently necessary part of any small-parts ultrasound study.

Peripheral pseudoaneurysms: evaluation with duplex US.

The prospectively generated results of 64 duplex sonographic examinations in 59 patients being evaluated for peripheral pseudoaneurysms over a 2-year period were reviewed. Subsequently, two groups of patients were identified. Group 1 (45 examinations) presented with relatively acute symptoms after arterial puncture, and group 2 (19 examinations) had undergone previous vascular surgical procedures and were usually asymptomatic. Duplex sonography demonstrated high sensitivity (94%) and specificity (97%) for the diagnosis of pseudoaneurysm in group 1. Of the 19 studies in group 2, duplex sonography allowed correct identification of pseudoaneurysms in four studies and exclusion of this entity in six examinations. The duplex sonographic findings in nine studies in this group did not allow differentiation of pseudoaneurysm from true aneurysm or oversize graft anastomosis. Duplex sonography is suggested as a primary radiologic method for evaluating possible pseudoaneurysms after arterial puncture, and it may provide valuable information and a means of postsurgical follow-up of selected patients as well.

Spiral CT of the abdomen: artifacts and potential pitfalls.

Spiral CT has been advocated as a major advancement in CT technology. Spiral CT scanning is rapid, the volume of IV contrast material can potentially be decreased, and high-quality coronal, sagittal, and three-dimensional reconstruction is possible. However, when compared with dynamic CT, because of the shorter acquisition time of spiral CT, vascular and organ enhancement on spiral CT scans is more dependent on factors that affect the delivery of contrast material into the bloodstream and on the time that scanning begins after the start of injection of contrast material. Additionally, organs other than the liver are scanned earlier than they typically are during a dynamic study, particularly the kidneys and spleen. In our experience to date, these aspects of spiral scanning have led to several difficulties in the interpretation of spiral CT scans. This essay illustrates potential pitfalls in the interpretation of spiral CT scans associated with scanning too soon after injection of contrast material.

Computed tomography of renal lymphomatoid granulomatosis.

Lymphomatoid granulomatosis is an uncommon disease that primarily involves the lungs. Although renal involvement has been demonstrated to be common in autopsy series, the CT appearance has not been previously described. In this report a patient with verified pulmonary lymphomatoid granulomatosis was demonstrated to have bilateral, nodular renal masses by CT which regressed completely with treatment. Although not pathologically proven, this is presumed to represent renal involvement by lymphomatoid granulomatosis.

Digital subtraction angiography for preoperative evaluation of extremity tumors.

A retrospective study was undertaken to evaluate the role of digital subtraction angiography (DSA) in the surgical planning of musculoskeletal neoplasms. Thirteen patients with primary bone and soft-tissue tumors were examined by CT and DSA. Three patients also had conventional angiography. DSA yielded surgically useful information in 10 patients, comparable to that expected from conventional angiography. DSA was most helpful in demonstrating the presence or absence of major vessel involvement by tumor when this could not be ascertained definitely on CT. Demonstration of mass extent by CT was accurate in 11 patients. Results of this study suggest that the combination of CT and DSA is useful in the preoperative evaluation of selected extremity tumors and should diminish the need for conventional angiography.

Hypoechoic renal pyramids: sonographic visualization in older children and young adults.

The frequency and degree of visualization of medullary pyramids in a normal population, aged 10-29 years, was analyzed. Hypoechoic pyramids were visualized in 42% of right kidneys in subjects aged 10-18 years and in 27% of subjects aged 19-29 years. Prominently hypoechoic pyramids, mimicking the appearance of neonatal kidneys, were seen in an additional 34% of subjects aged 10-18 years and in 16% aged 19-29 years. Prominent pyramids were present in 50% of subjects with renal cortical echogenicity (RCE) equal to liver, but also in 21% of subjects with RCE less than liver. Our study expands the age at which prominently hypoechoic medullary pyramids can be considered a normal finding. This may relate to recent improvements in ultrasound technology.

Tracheobronchial tree and pulmonary arteries: MR imaging using electronic axial rotation.

Standard coronal magnetic resonance (MR) imaging cannot depict long segments of the tracheobronchial tree and left pulmonary artery owing to the normal thoracic kyphosis and posteriorly angled course of these structures. By the use of electronic axial rotation (EAR), however, MR is capable of imaging any plane. We used EAR in 25 patients undergoing MR examinations of the thorax. This technique allowed superior definition of the longitudinal axis of the tracheobronchial tree and left pulmonary artery. The right pulmonary artery was satisfactorily imaged by the standard coronal plane.

Breast specimen radiography: evaluation of a compression device.

The irregular shape and uneven tissue thickness of excised breast specimens makes radiographic evaluation difficult, especially when calcifications are not present. Xeroradiographs before and after compression of 20 separate excised breast specimens were compared, and 17 of the same specimens were compared after compression combined with immersion in water. Specimen compression improved visibility of the lesion on average in 88% of cases, and visibility was equal in 12%. Combined compression/immersion further improved visibility of the lesion on average in 37% of cases. More significantly, evaluation of the compressed specimen led to a change in interpretation of the radiographs in 45% of cases. Compression of the specimen in specimen radiography is recommended in all cases in which pre-biopsy localization is performed.

Fibrotic lesions of the testicle: sonographic patterns mimicking malignancy.

All testicular sonograms performed over a 2.5-year period were retrospectively reviewed, yielding eight patients with pathologically proven lesions consisting primarily of tubular sclerosis and interstitial fibrosis. Only two patients (25%) had a palpable abnormality. A variety of sonographic patterns was found, including focal hypoechoic or hyperechoic lesions and diffuse heterogeneity of the testicular parenchyma. The clinical and sonographic findings prompted open biopsy or orchiectomy in all cases. In the same time period, nine pathologically proven testicular malignancies were evaluated sonographically and displayed either well-defined hypoechoic or diffusely heterogeneous echo patterns. All but two of these patients (78%) had palpable abnormalities. This study demonstrates a significant overlap in the sonographic appearance of benign fibrotic lesions and testicular malignancies. When careful palpation of a sonographically heterogeneous or focal hypoechoic lesion fails to reveal a mass and serum tumor markers are negative, an open biopsy with frozen section analysis should be considered rather than proceeding directly to orchiectomy. Homogeneously hyperechoic masses can be considered benign and do not require surgery.