PubMed Health⌕ Search

Biomedical subjects

R M Patten

Publications and source records attributed to R M Patten.

41 records · Page 3Linked to original sources
PubMedDate not supplied

OMR, a positive bowel contrast agent for abdominal and pelvic MR imaging: safety and imaging characteristics.

To determine the safety and imaging characteristics of OMR--an effervescent solution of ferric ammonium citrate--as a bowel contrast agent, magnetic resonance (MR) imaging at 1.5 T was performed in 29 volunteers. T1- and T2-weighted images of the upper abdomen and pelvis were obtained before and after oral administration of OMR at doses of 100-400 mg of iron in 300-600 mL of water. Respiratory-ordered phase encoding and presaturation pulses were used routinely for artifact suppression. All dose levels of OMR provided marking of the bowel by increasing intraluminal signal intensity; however, the degree and percentage of small bowel opacification appeared more prominent at higher dose levels of iron. Semisolid or watery bowel movements were noted in 31% of subjects, but no clinically important laboratory abnormalities were seen. OMR improved delineation of the head of the pancreas on T1-weighted images in 72% of subjects but was less useful in defining the body and tail. OMR is a safe and effective bowel contrast agent for MR imaging. Because artifacts due to movement of hyperintense bowel may degrade the images, OMR may be most useful on short TR/TE or fast imaging pulse sequences or when combined with antiperistaltic agents.

Abdomen↗
PubMedDate not supplied

Atraumatic osteolysis of the distal clavicle: MR findings.

OBJECTIVE: The purpose of this study was to describe the MRI appearance in atraumatic osteolysis of the distal clavicle (AODC). MATERIALS AND METHODS: We retrospectively evaluated MRI, medical records, ancillary diagnostic imaging studies and clinical course in five men and two women (mean age, 39 years) in whom the final clinical diagnosis of AODC was established. None of the patients had significant shoulder injury, but all participated in activities involving repetitive strain of the acromioclavicular (AC) joint. In three of these patients, we performed follow-up MRI (ranging from 5 1/2 to 15 months after the initial MRI). RESULTS: In all seven patients, signal intensity changes within the intramedullary portion of the distal clavicle on MRI were consistent with diffuse bone marrow edema. Marrow edema was most conspicuous on STIR imaging and occasionally could be misinterpreted as normal marrow signal patterns on spin-echo imaging. Cortical thinning or irregularity of the distal clavicle was seen in six cases and tiny subchondral cysts were seen in three, corresponding to subtle cystic changes on shoulder radiography. Limited bone scans obtained in two patients showed markedly increased uptake of radiotracer at the distal clavicle and AC joint. Histologic examination in one case showed disruption of articular cartilage, subchondral cysts, and metaplastic bone formation with increased osteoclastic activity. Follow-up MRI in three patients who were asymptomatic following conservative therapy showed normalization of marrow signal intensity. CONCLUSION: Atraumatic osteolysis of the distal clavicle is a relatively uncommon but important cause of shoulder pain. Particularly when the clinical history is suggestive of repetitive AC joint stress, MRI of the distal clavicle should be examined closely for marrow edema, cortical irregularity, and cystic changes. Such abnormalities may be especially conspicuous when STIR imaging techniques are used.

Acromioclavicular Joint↗
PubMedDate not supplied

MRI of meniscal allografts.

OBJECTIVE: To illustrate the techniques and the MRI appearance of meniscal transplants. MATERIALS AND METHODS: Three patients underwent MRI of the knee between 2 weeks and 14 months after meniscal transplantation. RESULTS: Although postoperative artifacts were present, in all three patients the position, signal intensity, and morphology of the postoperative menisci could be easily characterized with standard spin-echo techniques. In the early postoperative period in the patients with clinically acceptable surgical results, the meniscal allograft had an MR appearance indistinguishable from the native meniscus; follow-up MRI showed increasing signal intensity in the periphery of the menisci on double-echo spin-echo imaging. In one case complicated by a joint effusion developing 6 weeks after surgery, MRI showed displacement and deformity of the allograft. CONCLUSION: Although preliminary, these results demonstrate that MRI can readily show the morphology and position of the transplanted meniscus and suggest it may prove useful in the identification of both immediate and long-term complications of the procedure.

Adult↗
PubMedDate not supplied

Complete vs partial-thickness tears of the posterior cruciate ligament: MR findings.

OBJECTIVE: We sought to define the MRI appearance of both complete and partial-thickness tears of the posterior cruciate ligament (PCL) and to describe patterns of injury and associated MRI findings. MATERIALS AND METHODS: Three radiologists retrospectively reviewed MR images and medical records on 32 patients with PCL tears (15 complete, 17 partial) and correlated MRI findings to results of clinical testing and surgery. RESULTS: The PCL had indistinct margins in 27 (84%) of 32 patients and was abnormally thick in 25 (78%) patients. In 31 (97%) patients, the torn PCL showed increased signal intensity on both T1- and T2-weighted pulse sequences. Although there was no statistically significant difference between patients with complete tears and those with partial tears with regard to thickness, margination, and signal intensity of the PCL, MR images in patients with complete tears were more likely to show focal areas of ligamentous discontinuity (10 of 15 cases) (p = 0.01). Associated knee injuries were seen in 21 (66%) patients and were seen more frequently in patients with complete PCL tears (p = 0.015). Bony injury (n = 11, 34%) and tears of the medial collateral ligament (n = 13, 41%) and menisci (n = 10, 31%) were common. No specific pattern of bony injury was found. CONCLUSION: Posterior cruciate ligament tears can be diagnosed readily by multiplanar MRI using both morphological and signal intensity characteristics. Although differentiation between complete and partial-thickness PCL tears by MRI criteria alone is more problematic, complete tears are more likely to show focal areas of discontinuity and partial tears are more likely to show at least some intact fibers.

Adolescent↗