Acquired immunodeficiency syndrome (AIDS) of the abdominal organs: imaging features

The liver, spleen, biliary tract, pancreas, and kidneys are commonly affected by opportunistic infection, malignancy, and inflammatory disorders during the course of human immunodeficiency virus (HIV) infection. Clinical manifestations of solid abdominal visceral involvement are protean and usually nonspecific, but it is important to establish a specific diagnosis promptly in these often critically ill patients. This presentation reviews the cross-sectional imaging spectrum of HIV-associated lesions of these organs.

Using MR imaging to diagnose partial tears of the anterior cruciate ligament: value of axial images

OBJECTIVE

The purpose of this study was to determine the usefulness of axial MR imaging for diagnosing partial anterior cruciate ligament (ACL) tears and to determine if patients could be categorized as having stable or unstable partial ACL tears on the basis of criteria of axial MR imaging.

MATERIALS AND METHODS

We reviewed 238 patients who, over a 2-year period, underwent both MR imaging of the knee and arthroscopic evaluation of the ACL. According to arthroscopic examination, these patients had 143 normal ACLs, 67 complete ACL tears, and 28 partial tears. The 28 partial tears included 20 stable tears (no ACL deficiency) and eight unstable partial tears having ACL deficiency or requiring ACL reconstructive surgery. The axial MR images were retrospectively reviewed by two interpreters who were unaware of the arthroscopic findings, and decisions were reached by consensus. The ACL was classified according to its axial configuration and continuity.

RESULTS

By axial MR imaging criteria, we found 109 elliptical ACLs, 45 attenuated ACLs, three ACLs with increased intrasubstance signal intensity, six isolated ACL bundle signs, 19 ACLs that could not be visualized, and 56 cloudlike mass signs. Arthroscopically normal ACLs and stable partial tears were difficult to distinguish reliably on axial MR images. Unstable partial ACL tears could not be distinguished from complete ACL tears. However, using axial MR imaging, our observers were able to segregate stable ACLs (normal ligaments and stable partial tears) from unstable ACLs (unstable partial tears and complete tears) with 100% sensitivity and 96% specificity.

CONCLUSION

Axial MR imaging of the ACL may provide important diagnostic information for patients who have ACL injury. On axial MR images, stable ACLs were elliptical, attenuated, or showed as areas of increased intrasubstance signal intensity. At arthroscopy, attenuated ACLs represented normal ACLs (76%) and stable partial tears (24%). On axial MR images, the configurations that indicated unstable ligaments were isolated ACL bundle, nonvisualized ACL, and cloudlike mass.

Gastric cancer. Radiologic diagnosis

The development and refinement of double-contrast barium techniques over the past two decades have dramatically improved the radiologist's ability to detect gastric cancer and characterize gastric ulcers. This article presents the radiologic findings of both early and advanced gastric cancer and offers guidelines for differentiating benign versus malignant gastric ulcers.

Gastric cancer. Radiologic staging

CT scan and EUS play complementary roles in staging gastric cancer. CT scan is initially performed to detect local and distant metastases. Depending on institutional expertise, EUS may be considered for local staging. Laparoscopic staging may also be helpful in select patients. It is hoped that further improvements in these techniques will improve the ability to stage gastric cancer and thereby optimize patient treatment and outcome.

The legal ramifications of the NCCN practice guidelines

Physicians concerned about being sued for medical malpractice for following (or deviating from) a clinical practice guideline written by the National Comprehensive Cancer Network (NCCN) or otherreputable group should keep in mind one general principle: "Good medicine is good law." In other words, if a physician follows a course of action in line with the professional standard of care, regardless of whether or not he or she adheres to a particular guideline, that individual has little to worry about with regard to malpractice liability. The standard of care against which malpractice liability is measured is defined informally as "what a similar doctor would do under similar circumstances." Thus, if most oncologists observe the NCCN guidelines (or if their practice already comports with them), the guidelines will serve as the professional standard against which all oncologists' conduct will be measured. If oncologists ignore the NCCN guidelines, the malpractice standard will continue to reflect the way oncologists actually treat cancer patients.

Pancreaticobiliary manifestations of AIDS

The pancreas and the biliary tract are frequent sites of infectious, Inflammatory, and neoplastic disease in patients with HIV infection. However, the symptoms of pancreaticobiliary involvement may be relatively mild so that the prevalence of these disorders is probably underestimated. An appreciation of the imaging findings of HIV-associated pancreaticobiliary disorders is important because involvement of these organs may be the only criterion that establishes the diagnosis of AIDS (Table 1).

Renal manifestations of AIDS

The kidneys in patients with acquired immunodeficiency syndrome (AIDS) are subject to a variety of insults. Renal manifestations can be seen with imaging studies of AIDS patients. Computed tomographic (CT) and ultrasound (US) scans of 64 patients with AIDS and renal dysfunction were retrospectively reviewed and compared with clinical, laboratory, and, when available, biopsy results. Imaging abnormalities included increased cortical echogenicity, nephromegaly, pyelonephritis, lobar nephronia, focal masses caused by abscess and lymphoma, parenchymal calcification, hydronephrosis, and infarct. Generally, patients with AIDS as a result of intravenous drug abuse and those with multiple risk factors were more likely to have abnormalities demonstrated at imaging as well as poorer prognosis than were patients in the homosexual transmission group in this series. Although US should be the screening study used in patients with AIDS and suspected renal dysfunction, CT and magnetic resonance imaging may be necessary to identify focal infectious, ischemic, and neoplastic processes.

CT of the azygoesophageal recess in infants and children

The contour of the azygoesophageal recess (AER) as seen with computed tomography (CT) is an important indicator of mediastinal disorders. Radiologists must recognize, however, that the AER contour varies with patient age. The configuration of the AER is dextroconvex in children younger than 6 years, nonconcave (ie, equally divided between convex and straight) in children aged 6-12 years, and concave (or adult-like) in adolescents and young adults (aged 12-20 years). The cause of this variation is not certain; however, chest wall configuration does not seem to be an important factor. Although a convex AER is normal and common in pediatric patients, this normal appearance must be distinguished from that of mediastinal abnormalities (eg, foregut malformation cysts, vascular anomalies, lymphadenopathy), which can also produce obvious or subtle convexity of the AER. An appreciation for the age-related variation in AER configuration helps in the interpretation of CT scans. Criteria such as attenuation, morphologic characteristics, cephalocaudal extent, and multicompartmental involvement may be helpful in the differential diagnosis, but, generally, mediastinal abnormalities that alter the AER are nonspecific in appearance.

MRI of hepatic iron deposition in patients with renal transplant

Excess hepatic iron deposition was found in five of 15 (33%) renal transplant patients undergoing magnetic resonance (MR) screening for avascular necrosis of the femoral heads. Only one of these patients had overt liver disease. The number of prior blood transfusions was a significant factor for this deposition, whereas the age and sex of the patients, number and type of transplants, histocompatibility alleles (HLA), and years of hemodialysis and of chronic renal failure were not significant etiological factors. Liver/fat intensity ratios of less than 0.29 on T1-weighted images and ratios of less than 0.21 on T2-weighted images and a calculated T2 value of less than 35 ms were the best indicators of iron overload. Renal transplant patients are at great risk for excess hepatic iron deposition and MR imaging is a promising tool for the diagnosis of iron overload in this patient population.

Fractures of the dens complicating ankylosing spondylitis with atlantooccipital fusion

Patients with ankylosing spondylitis are prone to fractures. Fractures tend to occur in the lower cervical spine disc space. We describe 2 patients with odontoid fractures. Both patients had atlantooccipital fusion which may have increased their susceptibility for dens fractures. One patient had Crohn's disease.

The doctor's changing role in allocating U.S. and British medical services

Until the fourth decade of this century, British and American patients who could afford physician services paid for them out of their own pockets; those who could not relied on charity care or simply went without. Doctors functioned as independent contractor private practitioners in both Great Britain and the United States, allocating medical services in response to paying-patient demand — and their own consciences.

Beginning in the 1930s, health care financing on both sides of the Atlantic was restructured in dramatically different directions, and physicians’ allocational roles in their respective countries began diverging. Under the National Health Service (NHS), British general practitioners became essentially gatekeepers to health services, funneling patients to appropriate hospital and specialist care. As time went by they came more to resemble lockkeepers, regulating the queue for secondary and tertiary treatment resulting from governmental limits on health care spending — and from the limitations and inefficiencies of a system of rationing by waiting. In the U.S., on the other hand, efficiency was not at first a concern.

Biological monitoring: the employer's dilemma

The industrial workplace contains many potential health hazards that not only can cause great harm to workers, but also can destroy the employers' economic stability. Often these hazards are documented and dealth with, but frequently they are unknown. When health-conscious employers monitor the physical well-being of their employees in an effort to avoid the terrible personal and economic costs these hazards can produce, they may be supplying their employees with the documentation necessary to recover financially for their industrial illnesses. This Article analyzes this dilemma confronting employers. It describes the many factors employers must consider when deciding whether to institute a monitoring process that takes full advantage of technological developments in medical care. The Article suggests an approach employers may take until some of the disincentives surrounding the implementation of monitoring are removed.