MRI of bone marrow edema-like signal in the pathogenesis of subchondral cysts.

OBJECTIVE: To determine if a relationship exists between bone marrow edema-like signal and subchondral cysts on magnetic resonance imaging (MRI). DESIGN: Retrospective cohort of 32 patients with two sequential knee MRI. Patients with acute trauma, infection, neoplasm, or osteonecrosis were excluded. The degree of osteoarthritis was assessed using an adaptation of the Baltimore Longitudinal Study of Aging (BLSA) scale. Initial and follow-up exams were reviewed for presence, location, size and changes of marrow edema-like signal, subarticular cysts and cartilage abnormality. All locations in the knee were aggregated for analysis with descriptive statistics. RESULTS: The mean time interval between exams was 17.52 months (range 2.1-40.1 months). There were 23 cysts: 11 (47.8%) new, 6 (26.1%) increased size, 1 (4.4%) decreased size, and 5 (21.7%) no change in pre-existing lesions. Cysts always arose from regions of marrow edema-like signal. There were 68 subarticular areas of marrow edema-like signal: 16 (23.5%) new, 23 (33.8%) increased size, 17 (25%) decreased size, 11 (16.2%) resolved and 1 (1.5%) no change in pre-existing lesion. Marrow edema-like signal size always changed with cyst development: increased in 6/11 (54.5%), decreased in 2/11 (18.1%) and resolved in 3/11 (27.2%). Change in cyst size was always accompanied by a change in edema-like signal size. An MRI visible cartilage abnormality was adjacent to 87% (20/23) of cysts. The mean BLSA score changed from 2.6 to 3.6 indicating an overall progression of osteoarthritis. CONCLUSION: Subchondral cysts develop in pre-existing regions of subchondral bone marrow edema-like signal.

Percutaneous central catheters and peripheral intravenous catheters have similar infection rates in very low birth weight infants.

OBJECTIVE: We performed this study to determine if percutaneous central lines (PCLs) were associated with infection more often than peripherally placed intravenous catheters (PIVs). STUDY DESIGN: We conducted a retrospective, cohort study of 53 infants with PCLs inserted from March 1993 to February 1995 for evidence of catheter-related bloodstream infection and 97 cohorts with PIVs who were matched to the infants with PCLs by admission date and birth weight. We considered an infant to have catheter-related bloodstream infection if bacteremia occurred while the PCL or PIV was in place with no other identifiable infection focus. Statistical analyses were performed by using either Student's t test or the Mann-Whitney U test where appropriate. RESULTS: There were eight infections per 1000 catheter days of PCL use and nine infections per 1000 catheter days of PIV use. CONCLUSION: PCLs do not become infected more often than PIVs.

Dilated duct pattern at mammography.

PURPOSE: To determine the importance of a dilated duct pattern at mammography. MATERIALS AND METHODS: Mammograms obtained in 46 women with histopathologically proved, asymmetrically dilated ducts were retrospectively studied. The laterality and location of the asymmetrically dilated duct, the presence of branching, and associated findings such as microcalcifications, nipple discharge, and interval change were evaluated. RESULTS: Eleven patients (24%) had malignant results (ductal carcinoma in situ or invasive ductal carcinoma). Among these, six (54%) had suspicious microcalcifications. Nonsubareolar location and interval change are significant (P = .04) variables associated with malignancy. CONCLUSION: Mammographic asymmetrically dilated ducts in a nonsubareolar area that are associated with interval change, suspicious microcalcifications, or both warrant biopsy.

Mycotic aneurysm of the abdominal aorta: CT finding in three patients.

We present three cases of mycotic aneurysms of the abdominal aorta that were initially diagnosed with computed tomography (CT). The accuracy of CT as the first imaging technique in the diagnosis of this condition is reviewed in light of our results and those reported in the literature.

Bowstring injury of the flexor tendon pulley system: MR imaging.

OBJECTIVE. The flexor tendon pulley system is often ruptured when a flexed finger is forcibly extended. In the acute phase, soft-tissue swelling and pain often make clinical evaluation difficult. These pulleys are not constantly visualized on MR imaging. Rupture of the pulley system can be inferred by observing bow stringing of the underlying flexor tendons when MR imaging is obtained with the finger in flexion. Our objective is to describe the flexor tendon pulley system and present our MR technique.

Thoracic duct function in fetal, newborn, and adult sheep.

We measured thoracic duct lymph flow rate versus outflow pressure in 7 chronically catheterized adult sheep and in 6 newborn lambs and compared our results to data previously obtained from 10 fetal sheep. In fetal sheep the thoracic duct lymph flow rate was 34.5 +/- 17.2 ml/hr or 11.7 +/- 6.0 ml/kg/hr. Fetal thoracic duct lymph flow deviated from baseline between 8 and 12 torr outflow pressure and lymph stopped at 18 +/- 2.5 torr. In newborn lambs the thoracic duct lymph flow rate was 49.5 +/- 22.0 ml/hr or 7.4 +/- 2.5 ml/kg/hr. The range of outflow pressures over which newborn lymph flow deviated from baseline was between 15 and 18 torr and lymph flow stopped at 26.2 +/- 6.4 torr. Adult sheep thoracic duct lymph flow rate was 130 +/- 74 ml/hr or 2.3 +/- 1.3 ml/kg/hr. Adult lymph flow deviated from baseline between 25 and 35 torr and stopped at an outflow pressure of 41.7 +/- 6.7 torr. The ability of the thoracic duct to return lymph against an outflow pressure improves with maturation. However, lymph flow rate corrected for body weight is greatest in immature animals. The higher corrected lymph flow rate in conjunction with the decreased ability to pump against an outflow pressure may help account for immature animals predisposition for edema.

The magic angle effect in musculoskeletal MR imaging.

The "magic angle" effect in magnetic resonance (MR) imaging is caused by changes in the dipolar interactions between water hydrogen protons that are loosely bound along collagen fibrils in organized tissue such as tendon or articular cartilage. When tendons are aligned at 55 degrees to the main magnetic field, the T2 relaxation time is lengthened, causing focal increased signal on short echo time MR images. Tendons in the ankle, wrist, and rotator cuff of the shoulder are common sites to observe this effect. Distinguishing magic angle effect from pathologic signal abnormalities due to degeneration or partial tears requires close comparison between T1- and T2-weighted images, as well as evaluation for secondary signs of injury such as tendon thickening or associated fluid.

Flow reversal in the right anterior branch of the portal vein: "bicolor portal vein" color Doppler analysis.

The purpose of this study is to describe a phenomenon of bidirectional flow, "bicolor portal vein" (BPV), within the right anterior branch of the portal vein (RAPV), with color Doppler imaging (CDI). We prospectively studied with CDI the intrahepatic portal vein and its branches in 316 consecutive patients in search of areas of nonlaminar flow within the RAPV. Forty patients were excluded from the study due to varied conditions that precluded an accurate CDI study. A prospective design allowed us to record the frequency of appearance, systematically measure a set of parameters in each patient, and establish different groups for comparison. We found an area of BPV within the RAPV in six patients. Five of them had a history of liver disease (8.2% of the patients with known liver disease). The BPV was consistently portrayed as a well-defined blue oval-shaped area of flow reversal attached to the medial side of the RAPV immediately before its bifurcation, suggesting a rotary motion of blood. All six patients presented a transverse diameter of the RAPV significantly larger than the rest of the patients (p < 0.05). Furthermore, blood flow measurements within the RAPV of the six patients with BPV were found to be significantly higher when compared with the rest of the patients (< 0.05). Knowledge of the possible presence of a BPV within the RAPV can prevent diagnostic confusion with reversal of flow, a truly pathologic condition related to liver disease.

Malignant neuroectodermal tumour of the chest wall (Askin tumour): CT and MR findings in eight patients.

Malignant neuroectodermal tumour of the chest wall (Askin tumour) is an uncommon malignant neoplasm affecting young adults. We retrospectively reviewed the clinical and pathological information and radiologic studies in our archives on eight cases of this tumour. All cases were pathologically proven. Plain films, CT scans and radionuclide images were available in all cases. MR images were also available in two patients. Although rare, Askin tumour should be included in the differential diagnosis when a chest wall or thoracic paraspinal mass is identified in a young individual.

Carcinoid tumors of the pancreas: CT findings.

Computed tomographic (CT) and ultrasound (US) findings in four cases of carcinoid tumors of the pancreas are reported. Differential diagnosis with other endocrine and nonendocrine pancreatic tumors is discussed. CT and US techniques play an important role in diagnosis, prognosis, and treatment of these tumors.