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Biomedical subjects

J H Mink

Publications and source records attributed to J H Mink.

At least 37 records · Page 2Linked to original sources
PubMed1991

Patellofemoral joint: evaluation during active flexion with ultrafast spoiled GRASS MR imaging.

An ultrafast spoiled gradient-recalled acquisition in the steady state pulse sequence was developed that permits multiple images to be obtained at a temporal resolution suitable for examining the patellofemoral joint during active flexion. This pulse sequence was used to perform kinematic magnetic resonance imaging of patellar alignment and tracking in five healthy subjects and seven patients with a provisional clinical diagnosis of abnormal patellofemoral joints.

Female↗
PubMed1991

Acute effects of exercise on MR imaging of skeletal muscle: concentric vs eccentric actions.

Eccentric (lengthening) muscle actions involve the forced lengthening of active muscles. Compared with concentric (shortening) muscle actions subjected to the same relative work load, eccentric actions have lower oxygen consumption requirements, fewer activated motor units, and less lactate production. This study was conducted to determine if T2-weighted MR could show any difference in muscles performing these specific types of actions and, therefore, be useful for physiologic investigations of eccentric and concentric actions. Five subjects performed exhaustive exercise by doing isolated concentric actions (raising a dumbbell, flexing at the elbow) and eccentric muscle actions (lowering a dumbbell, extending the contralateral arm). T2-weighted MR images of the arms were obtained immediately before and after exercise. Muscles that performed concentric actions had increases in signal intensity, whereas muscles that performed eccentric actions showed little or no change. T2 relaxation times increased significantly (p less than .01) in all volunteers, but T2 relaxation times for the muscles that performed concentric actions were significantly higher than those for muscles that performed eccentric actions (p less than .01). Therefore, T2 times increased with both concentric and eccentric actions, but the images failed to show the changes in the muscles that performed the eccentric actions. These data demonstrate that assessment of T2 values can be used to distinguish between muscles that perform concentric actions and those that perform eccentric actions, and this phenomenon may be useful for further physiologic investigations of these specific types of muscle actions.

Adult↗
PubMed1991

Do asymptomatic marathon runners have an increased prevalence of meniscal abnormalities? An MR study of the knee in 23 volunteers.

Excessive repetitive musculoskeletal loads and stresses associated with intense physical activity may lead to deterioration of the menisci of the knee. Therefore, MR imaging was performed on the knees of 23 asymptomatic marathon runners (eight men, 15 women; average age, 40 years; average number of years training, 10; average training distance per week, 41 miles) to determine the prevalence of meniscal signal abnormalities. None of the runners had previous knee injuries or surgery and each of them regularly competes in 26-mile, 50-mile, or 100-mile marathon races. T1-weighted coronal MR images and proton density-weighted and T2-weighted sagittal images were obtained with a 1.5-T MR system and a transmit/receive extremity coil. The medial and lateral menisci were divided into four portions, or horns, and a total of 92 horns were evaluated (i.e., four horns per knee: medial posterior, medial anterior, lateral posterior, and lateral anterior). Two meniscal horns (2%) had grade 3 signal (grade 3 indicates a meniscal tear), 12 (13%) had grade 2 signal, 29 (32%) had grade 1 signal (grades 1 and 2 are indicative of meniscal degeneration), and 49 (53%) had grade 0 signal (grade 0 is normal). Overall, the prevalence of meniscal tears was 9% (two meniscal tears found in 23 runners). This is lower than the prevalence of MR signal abnormalities indicative of meniscal tears reported for asymptomatic, nonrunner athletes (20% of 20 athletes) and for asymptomatic nonathletes (16% of 74 subjects). Fifty-three percent of the meniscal horns of the nonrunner athletes had grade 1 or 2 signal, indicative of meniscal degeneration. Our results indicate that the prevalence of meniscal tears in marathon runners is no higher than the prevalence reported for sedentary persons, and the runners have the same amount of meniscal degeneration as do nonrunner athletes.

Adult↗
PubMed1991

Tendon injuries of the lower extremity: magnetic resonance assessment.

MR is rapidly establishing itself as a premiere imaging modality for the assessment of musculoskeletal trauma. Its utility in the evaluation of the menisci and ligaments of the knee is well known, but there is far less known about the use of MR for evaluation of the tendons. MR, by virtue of its unmatched soft tissue resolution capability, can determine not only the contour of an affected tendon, but the tendon sheath and internal signal alterations that accompany tendonitis, partial and complete ruptures. Injuries to the Achilles tendon are well known to the athlete and the imager alike; however, abnormalities of the posterior tibial tendon, peroneal tendon, and flexor hallucis longus also result in significant clinical symptoms, as well as imaging abnormalities.

Athletic Injuries↗
PubMed1991

Kinematic magnetic resonance imaging of the joints: techniques and clinical applications.

Recently, kinematic magnetic resonance imaging (MRI) techniques have been developed to provide diagnostic information related to the functional aspects of the joints. The kinematic MRI evaluation of the joint is used to assess the various interactions of the soft tissues and bony anatomic structures that comprise the joint, and to evaluate the relative alignment of these structures through a specific range of motion. The use of kinematic MRI techniques for examination of the joints provides the radiologist and the clinician with augmented data of anatomic and movement-related information.

Humans↗
PubMed1990

Evaluation of patients with persistent symptoms after lateral retinacular release by kinematic magnetic resonance imaging of the patellofemoral joint.

The arthroscopic lateral retinacular release is typically performed to treat patellar pain and instability. This procedure was previously considered to be relatively benign with a low associated complication rate. However, a high incidence of medial subluxation of the patella was recently reported in patients with persistent symptoms after lateral retinacular release. Because the use of physical examination criteria may not always be sufficient to assess patellar alignment, 40 patients (43 knees) were evaluated by the newly developed technique of kinematic magnetic resonance imaging of the patellofemoral joint. One (2%) patellofemoral joint had normal patellar alignment, 10 (23%) had lateral subluxation of the patella, 1 (2%) had excessive lateral pressure syndrome, 27 (63%) had medial subluxation of the patella, and 4 (9%) had lateral-to-medial subluxation of the patella. Seventeen of 40 patients (43%) with unilateral arthroscopic lateral retinacular releases had medially subluxated patellae on the unoperated joints. Because patellar malalignment commonly affects bilateral joints, medial subluxation of the patella may have been present before the lateral retinacular release but was not recognized in these patients.

Adult↗
PubMed1990

Peripheral meniscal tears: MR findings after conservative treatment or arthroscopic repair.

Follow-up knee magnetic resonance (MR) examinations were performed on 17 patients (18 menisci) with arthroscopically proved tears of the outer third of the meniscus who were treated either conservatively (six patients) or with surgical repair (11 patients). All patients satisfied accepted clinical orthopedic criteria for meniscal healing. MR examinations obtained 3-27 months after injury revealed persistent signal intensity (grade 3), unchanged from that seen on the preoperative study, in all 15 patients in whom both pre- and postoperative studies were obtained and in three of four menisci that were proved to be healed at second-look arthroscopy. It appears that grade 3 signal from both conservatively treated and repaired menisci may persist long after the tear has become asymptomatic and has presumably healed. The presence of such signal should not be interpreted as necessarily indicating meniscal retear in these patients. Persistent signal intensity at the site of previous injuries may account for some reported cases of disagreement between MR and arthroscopic findings.

Adolescent↗
PubMed1990

Magnetic resonance imaging of injuries to bone and articular cartilage. Emphasis on radiographically occult abnormalities.

Magnetic resonance imaging (MRI) has emerged as the premier noninvasive imaging method for evaluation of the musculoskeletal system. Among the most widely recognized and accepted applications of MRI is that of trauma-related imaging. While the initial emphasis on MRI was directed toward the assessment of soft-tissue structures previously difficult to image (eg, knee menisci and cruciate ligaments), it has become increasingly apparent that MRI is superbly suited to the depiction of a wide spectrum of injuries to bone and articular cartilage. MRI has proved capable of depicting abnormalities ranging from clinically innocuous bone bruises to posttraumatic osteonecrosis. Many of the abnormalities that have been detected by MRI have been radiographically occult and often clinically unsuspected. MRI has become established in the assessment of chondral and osteochondral injuries, insufficiency and stress fractures, occult proximal femoral fractures, tibial plateau fractures, and scaphoid injuries. This review will attempt to present the current state of the art with respect to the application of MRI to the assessment of injuries to bone and articular cartilage. Particular emphasis will be placed on radiographically occult abnormalities.

Bone Diseases↗
PubMed1989

Occult fractures of the proximal femur: MR imaging.

Coronal T1-weighted magnetic resonance (MR) images were obtained on a 1.5-T system in 23 patients in whom there was a high clinical suspicion of hip fracture although initial radiographs were normal. MR imaging correctly demonstrated fracture in nine of nine patients; the precise configuration of the fracture line was delineated in eight patients. MR imaging was useful in excluding fractures in 14 of 14 patients, who were subsequently followed up clinically for a minimum of 3 months. Radionuclide scans were positive in four of four patients with fractures and equivocal in one patient who was subsequently demonstrated to have no fracture. Additional imaging studies were requested by clinicians in all cases in which the bone scan was positive. The results of this study suggest that MR imaging can provide a rapid, cost-effective, and anatomically precise diagnosis of hip fracture in patients with normal or equivocal initial radiographs. The specificity of the diagnosis achieved can obviate supplemental imaging examinations, with their attendant additional expense and radiation exposure.

Aged↗
PubMed1989

Occult cartilage and bone injuries of the knee: detection, classification, and assessment with MR imaging.

Scant attention has been paid to the role of magnetic resonance (MR) imaging in the assessment of posttraumatic disorders of bone and cartilage at the knee. The authors reviewed 66 cases and identified four types of injuries that were not clearly evident on plain radiographs. A bone bruise was the most common lesion, having a high association with anterior cruciate ligament tears. Osteochondral fractures, stress fractures, and supracondylar femoral and tibial plateau fractures were also identified. MR imaging appears extremely useful in the detection and assessment of bone and cartilage disorders around the knee.

Cartilage, Articular↗
PubMed1989

Patellar tracking abnormalities: clinical experience with kinematic MR imaging in 130 patients.

A kinematic magnetic resonance (MR) imaging technique for assessment of malalignment of the patella, involving the acquisition of multiple sequential axial images of the patellofemoral joint during the early increments of passive knee flexion, was used to evaluate 130 patients (235 symptomatic patellofemoral joints) showing clinical evidence of having patellar tracking abnormalities. Twenty-three of the patellofemoral joints had undergone previous surgical procedures for patellar realignment. In addition, 14 (28 patellofemoral joints) asymptomatic control subjects were studied. Normal patellar tracking was observed in all of the asymptomatic subjects and in 43 (17%) of the 260 patellofemoral joints in the patient population, 18 (7%) of which were symptomatic. Sixty-nine (26%) of the patellofemoral joints had lateral subluxation of the patella, 106 (41%) had medial subluxation of the patella, 21 (8%) had excessive lateral pressure syndrome, 19 (7%) had lateral-to-medial subluxation of the patella, and two (1%) had dislocation of the patella. Of the 235 patellofemoral joints with suspected abnormalities, 217 (93%) had patellar malalignment. Of the 23 patellofemoral joints that had undergone prior surgery, 20 (87%) had abnormal patellar tracking. Thirteen of 14 (93%) patellofemoral joints that had undergone a prior arthroscopic lateral retinacular release had a medially displaced patella.

Adult↗
PubMed1989

Discoid menisci of the knee: MR imaging appearance.

Discoid menisci of the knee are not uncommon, and the criteria for arthrographic diagnosis and the clinical symptoms are well known. Although enlarged menisci have been recognized at magnetic resonance (MR) imaging, there are no criteria for the MR imaging diagnosis. The authors describe 29 discoid menisci imaged by means of MR. A discoid meniscus was said to be present if three or more 5-mm-thick contiguous sagittal images demonstrated continuity of the meniscus between the anterior and posterior horns. High-resolution coronal images allowed more graphic depiction of the abnormally wide meniscus. In approximately one-third of the cases in which coronal images were obtained, the measurable height difference between the discoid and the opposite meniscus was greater than or equal to 2 mm. Arthroscopic correlation (obtained in 10 cases) revealed that six cases of discoid meniscus were diagnosed correctly with MR imaging, although one meniscus was considered discoid at MR imaging but was not considered discoid at arthroscopy. Of three discoid menisci seen to be torn at arthroscopy, two were seen to be torn at MR imaging.

Adult↗
PubMed1989

Incidental detection of hematopoietic hyperplasia on routine knee MR imaging.

An unusual appearance of the marrow of the distal femur, characterized by confluent foci of diminished signal intensity replacing the normally expected bright signal of fatty marrow on all pulse sequences, was encountered in 10 asymptomatic patients undergoing routine knee MR imaging. This prompted initial concern about the possibility that this appearance was due to lymphoma or occult myeloproliferative malignancy. All patients were mild to moderately obese, and all but one were women. Peripheral blood analysis was obtained in nine patients and was normal in five. The other four were cigarette smokers with a peripheral leukocytosis. Bone-marrow biopsy of the distal femur in two patients and of the iliac crest in three, performed to exclude malignancy, showed hypercellular but otherwise normal-appearing hematopoietic (red) marrow. The patients have been followed for 4-15 months without evidence of malignancy. We conclude that extensive foci of hematopoietic marrow may be encountered incidentally in patients undergoing MR examination. Careful follow-up to date suggests that this most likely represents a benign process and that patients in whom this appearance is encountered can be managed conservatively.

Adult↗
PubMed1989

Imaging evaluation of the candidate for percutaneous lumbar discectomy.

Percutaneous lumbar discectomy has been advocated as an alternate means of treating lumbar disc disease. A disc treatable by this method must not be free in the spinal canal and cannot be above or below the disc space. Magnetic resonance imaging, computed tomography, and discography all can be valuable in selecting patients for percutaneous lumbar discectomy.

Humans↗
PubMed1989

Magnetic resonance imaging of the knee.

Magnetic resonance imaging (MRI) is gaining acceptance as the diagnostic imaging procedure of choice for the disorders of the knee. MRI can reliably display tears of the menisci and ligaments. It also has an unmatched capability of detecting and assessing a wide spectrum of knee disorders that may be present as nonspecific knee pain: osteonecrosis, osteochondritis dissecans, stress fracture, bone and soft-tissue tumors, and vascular abnormalities. Practicing orthopedists should become better acquainted with this powerful diagnostic tool that can be an invaluable asset to their clinical practices.

Adult↗
PubMed1989

Magnetic resonance imaging of musculoskeletal injuries.

Magnetic resonance (MR) imaging has been applied toward the assessment of a wide spectrum of injuries to the musculoskeletal system. This use of MR imaging has been enthusiastically accepted by orthopedic surgeons, and the assessment of musculoskeletal trauma has emerged as one of the most commonly utilized applications of this diagnostic method. This article encompasses the major applications of MR imaging in the assessment of injuries to bone and soft tissue. Emphasis is placed on the most commonly encountered conditions, namely, those that are accidental, exercise-, and sports-related. Technical considerations as they pertain to the design and interpretation of trauma-related musculoskeletal MR imaging are addressed.

Fractures, Bone↗