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Biomedical subjects

D A May

Publications and source records attributed to D A May.

At least 19 recordsLinked to original sources
PubMed2000

Case report: prenatally detected dumdbell-shaped retroperitoneal duplication cyst.

Enteric duplication cysts are infrequently located in the retroperitoneum. Such cysts are typically spherical or ovoid. We report a retroperitoneal duplication cyst with extension across the abdominal midline in a previously unreported dumbbell configuration. This is the third reported case of prenatally detected retroperitoneal enteric duplication cyst.

Abdomen↗
PubMed2000

Abnormal signal intensity in skeletal muscle at MR imaging: patterns, pearls, and pitfalls.

Abnormal signal intensity within skeletal muscle is frequently encountered at magnetic resonance (MR) imaging. Potential causes are diverse, including traumatic, infectious, autoimmune, inflammatory, neoplastic, neurologic, and iatrogenic conditions. Alterations in muscle signal intensity seen in pathologic conditions usually fall into one of three recognizable patterns: muscle edema, fatty infiltration, and mass lesion. Muscle edema may be seen in polymyositis and dermatomyositis, mild injuries, infectious myositis, radiation therapy, subacute denervation, compartment syndrome, early myositis ossificans, rhabdomyolysis, and sickle cell crisis. Fatty infiltration may be seen in chronic denervation, in chronic disuse, as a late finding after a severe muscle injury or chronic tendon tear, and in corticosteroid use. The mass lesion pattern may be seen in neoplasms, intramuscular abscess, myonecrosis, traumatic injury, myositis ossificans, muscular sarcoidosis, and parasitic infection. Some of these conditions require prompt medical or surgical management, whereas others do not benefit from medical intervention. The ability to accurately diagnose these conditions is therefore necessary, and biopsy may be required to establish the correct diagnosis. Clues to the correct diagnosis and whether biopsy is necessary or appropriate are often present on the MR images, especially when they are correlated with clinical features and the findings from other imaging modalities.

Adolescent↗
PubMed2000

Neuropathic osteoarthropathy: diagnostic dilemmas and differential diagnosis.

The purpose of this pictorial essay is to illustrate the radiologic spectrum of imaging findings of neuropathic osteoarthropathy. Typical findings include joint destruction, disorganization, and effusion with osseous debris. A variety of other imaging findings related to neuropathic osteoarthropathy such as resorption of the ends of tubular bones and neuropathic fracture are shown. The two prevailing theories for the pathophysiology of neuropathic bone and joint disease, the neurovascular and neurotraumatic theories, are briefly described. Examples of osteoarthropathy from diverse causes are presented including syringomyelia, spinal cord injury, meningomyelocele, diabetes mellitus, congenital insensitivity to pain, steroid injections, syphilis, leprosy, and others. The discussion focuses on key imaging features with emphasis on disease patterns and differential diagnosis, which vary by skeletal location.

Adolescent↗
PubMed2000

Articular cartilage defects: in vitro evaluation of accuracy and interobserver reliability for detection and grading with US.

PURPOSE: To determine the accuracy and reliability of detecting and grading articular cartilage defects in porcine and human knees by using ultrasonography (US). MATERIALS AND METHODS: US was used to evaluate 175 porcine and 16 human knee surfaces with a linear 5-12-MHz transducer. Porcine defects of varying diameter and depth were surgically created. Each porcine surface was independently assessed in blinded fashion by two radiologists for the presence and severity of defects. Accuracy of detection, interobserver reliability, and concordance between US and surgical grades were determined. Human specimens were retrieved from knees of patients who underwent joint arthroplasty. Defects in human knees detected with US were correlated with defects seen at direct surface visualization. RESULTS: Sensitivities for detection of porcine defects were 94% and 93% for readers 1 and 2, respectively; specificities were 90% and 77%, respectively; positive predictive values were 98% and 95%, respectively; and negative predictive values were 78% and 73%, respectively. Interobserver agreement was high (weighted kappa = 0.80), and concordance between US and surgical grades for both readers was high (weighted kappa = 0.90 and 0.78). In human cartilage, the distribution of cartilage denudation determined at US was the same as that determined at direct visualization. CONCLUSION: High-frequency US was accurate and reliable for detection and grading of knee articular cartilage defects.

Animals↗
PubMed2000

Effect of gadolinium concentration on renal signal intensity: An in vitro study with a saline bag model.

PURPOSE: To compare the effects of gadolinium concentration on intermediate-weighted fast inversion-recovery and T2-weighted fast spin-echo magnetic resonance (MR) images by using a saline bag model of the kidney. MATERIALS AND METHODS: Normal-saline bags containing gadopentetate dimeglumine in concentrations of 0-20 mmol/L were imaged by using a variety of pulse sequences. Signal intensity was measured. RESULTS: Signal intensity loss at high gadolinium concentrations (negative enhancement) was demonstrated with all MR sequences. Increasing T2 weighting increased the negative enhancement effect and reduced the minimum gadolinium concentration at which negative enhancement was seen. The results of this study match theoretic predictions. CONCLUSION: The negative enhancement of normal renal tissue seen in intermediate-weighted fast inversion-recovery MR imaging is caused by T2 shortening at high gadolinium concentrations. Thus, gadolinium-enhanced T2-weighted fast spin-echo imaging also is expected to show negative enhancement and may prove to be a superior sequence for MR imaging of pyelonephritis. Further clinical investigation is warranted.

Child, Preschool↗
PubMed1998

Intercondylar notch encroachment following anterior cruciate ligament reconstruction: a prospective study.

Intercondylar notch impingement is a recognized cause of graft failure following anterior cruciate ligament (ACL) reconstruction and typically is attributed to anterior tibial tunnel placement or inadequate notchplasty. This prospective study assessed the incidence and nature of notch regrowth following initial ACL reconstruction. The study population was comprised of 36 patients who underwent ACL reconstruction using a patellar tendon-bone autograft. A 3- to 5-mm notchplasty was performed in all patients, and an intraoperative radiograph was taken confirming proper tunnel placement. Magnetic resonance imaging (MRI) was performed the first week following surgery and again at 6 months. The MRIs were reviewed by two skeletal radiologists to evaluate postoperative notch and graft changes. Of the 36 study patients, 28 (78%) knees showed no evidence of graft impingement as defined by graft indentation and intra-substance edema. The MRIs of 8 (22%) patients showed evidence of graft impingement. Four patients had clinical signs of graft impingement, namely persistent effusion or lack of full extension. Arthroscopically, 3 of these patients demonstrated graft encroachment and impingement by fibrocartilage with areas of immature bone. These results indicate that graft impingement from regrowth of the notch is a clinically relevant phenomenon that could potentially result in late graft demise in the ACL-reconstructed knee.

Adult↗
PubMed1997

MR imaging of musculoskeletal tumors and tumor mimickers with intravenous gadolinium: experience with 242 patients.

PURPOSE: This pictorial essay reviews our experience with MR scans with gadolinium in patients with musculoskeletal tumors and tumor mimickers. DESIGN: Review of 242 MR scans obtained in the initial evaluation of a possible primary musculoskeletal neoplasm. All scans included a T1-weighted, fat-suppressed sequence following intravenous administration of gadolinium. RESULTS: MR scans with gadolinium did not contribute to differential diagnosis or patient management in 89% of the patients in this series. However, intravenous gadolinium did assist in guiding the biopsy of bulky lesions and evaluating treated tumor beds for possible recurrence. MR scans with gadolinium were sometimes helpful when the differential diagnosis included synovitis, Morton's neuroma or intramuscular myxoma, and when it was important to differentiate cystic from solid lesions. CONCLUSIONS: Routine use of gadolinium in every initial MR examination of a possible musculoskeletal mass is not warranted. However, there are appropriate selected indications for gadolinium administration as outlined above.

Adolescent↗
PubMed1997

MR imaging findings in anterior cruciate ligament reconstruction: evaluation of notchplasty.

OBJECTIVE: Notchplasty, resection of bone from the roof and lateral side of the inter-condylar notch, is frequently performed during anterior cruciate ligament (ACL) reconstruction to avoid abrasion or deflection of the ACL graft by the femur (graft impingement). Graft impingement can develop months after the initial reconstruction despite adequate notchplasty. Such impingement has recently been attributed to fibrocartilage overgrowth of the notchplasty site. The objectives of this study were to evaluate the MR appearance of the notchplasty site immediately after surgery and 6 months later and to investigate whether cartilage overgrowth of the notchplasty site can be detected with MR imaging. SUBJECTS AND METHODS: Thirty-three patients who underwent bone-tendon-bone autograft ACL reconstruction had MR scans of the intercondylar notch 6 months after surgery. Twenty-five of these patients also had MR scans in the immediate postoperative period. The appearance of the notchplasty site and evidence for cartilage overgrowth of the notchplasty site were evaluated. Arthroscopic correlation was available for six patients. RESULTS: On MR images, the margins of the notchplasty site were identified in all patients. Contour of the notchplasty site along the lateral notch wall was frequently concave toward the notch, a finding not commonly seen in an unoperated notch. Six months later, the shape of the notchplasty site had not changed, but evidence for recortication of the notchplasty site (seen as a layer of signal void 0.5-1.5 mm in thickness over the previously exposed cancellous bone) was seen in 94% of the patients. Additionally, a second layer of signal void, 1-5 mm in thickness with signal intensity identical to that of hyaline cartilage, was seen overlying the notchplasty site in 64% of patients. Arthroscopic correlation available in six patients suggested that this second layer represented fibrocartilage overgrowth of the notchplasty site. CONCLUSION: Characteristic changes of the intercondylar notch after notchplasty can be seen on MR images. This preliminary study also suggests that a thin layer of cortical bone forms over the notchplasty site in most patients within 6 months of surgery. Perhaps more significantly, overgrowth of the notchplasty site by fibrocartilage may also be detected in some patients. Further experience is needed to determine whether MR imaging is a useful method for identifying cartilage overgrowth after notchplasty.

Adolescent↗
PubMed1996

MR imaging of the anterior cruciate ligament: frequency of discordant findings on sagittal-oblique images and correlation with arthroscopic findings.

OBJECTIVE: The purposes of this study were to determine the frequency of discordant MR findings of the anterior cruciate ligament (ACL) using sagittal-oblique images and the arthroscopic integrity of the ACL in knees with a discordant MR appearance. MATERIALS AND METHODS: The frequency of discordant MR features was determined by independently reviewing the sagittal-oblique images of 53 consecutive patients undergoing subsequent arthroscopic surgery. The first 25 consecutive knees were examined using a conventional, dual-echo, T2-weighted spin-echo (SE) sequence; the subsequent 28 consecutive knees were examined using both a T1-weighted SE(T1) and a fat-suppressed, fast spin-echo (FSE) T2-weighted sequence. Two examiners who were unaware of patient identification and arthroscopic results evaluated only the sagittal images that included the ACL. Each reviewer graded the ACL as torn or intact. The MR appearance was considered discordant when one MR sequence showed disrupted or poorly seen ACL fibers and the other sequence showed intact ACL fibers. The arthroscopic integrity of the ACL was determined for the 20 knees with a discordant MR appearance. RESULTS: A discordant MR appearance of the ACL was seen in 20 of the 53 knees (38%), including 10 knees evaluated using conventional T2-weighted sequences (40%) and 10 knees using T1/FSE T2 (36%) sequences. Arthroscopic examination of these knees showed intact ACL fibers in all 20 knees; the ACL was normal in 18 knees and a partial tear was questioned in two knees. CONCLUSION: A discordant appearance of the ACL was frequently encountered (38%) using either conventional T2-weighted sequences or T1 and FSE MR sequences in the sagittal-oblique plane. Intact ACL fibers were found during arthroscopy in all 20 knees with a discordant MR appearance.

Adult↗
PubMed1996

MR imaging of occult traumatic fractures and muscular injuries of the hip and pelvis in elderly patients.

Recent studies have shown the usefulness of T1-weighted MR imaging for identifying fractures of the proximal femur in elderly patients with negative radiographs after acute trauma [1-4]. The advent of fast spin-echo and fast inversion recovery sequences allows for the rapid identification of a variety of other musculoskeletal injuries of the hip and pelvis that may explain a patient's symptoms but that may not be seen on T1-weighted images. This pictorial essay shows the types of lesions encountered. Lesion prevalence is given for 20 consecutive patients examined.

Acetabulum↗
PubMed1993

Perinatal and postnatal chest sonography.

Sonography is the primary method used to image the fetal chest. Many significant congenital anomalies such as pleural effusion, congenital diaphragmatic hernia, cystic adenomatoid malformation, pulmonary sequestration, and congenital heart disease can be detected during early prenatal sonography. Fetal sonography also permits accurate assessment of the severity of these processes, allowing for parental counseling and optimal planning of postnatal care. After birth, sonography is the primary method for evaluating cardiac anatomy and diagnosing congenital heart disease. Sonography also serves as a useful adjunct to plain film radiology and other modalities in evaluation of the mediastinum, diaphragm, pleura, and chest wall.

Bronchopulmonary Sequestration↗
PubMed1991

Embryonal heart rate as a predictor of pregnancy outcome: a prospective analysis.

To evaluate the association between embryonal heart rate and pregnancy outcome, we prospectively followed 50 very early pregnancies (4.5 to 7.3 weeks of gestation) through the first trimester. Of the 11 embryos that miscarried, 6 had initial heart rates below 85 beats per minute (bpm); in contrast, none of the viable embryos had initial heart rates of or below 85 bpm (P less than 0.0001). A rise in mean heart rate was seen among the viable embryos with increasing gestational age, in concordance with previously reported rates.

Abortion, Spontaneous↗