Biomedical subjects

G J Garvin

Publications and source records attributed to G J Garvin.

6 recordsLinked to original sources

PubMed1997

Two-arm trajectory planning in a manipulation task.

This paper addresses the trajectory planning problem for a task which requires positioning and orienting an object firmly grasped by two hands at a visually specified goal configuration in the horizontal plane. The motor task involves three degrees of freedom (two translational and one rotational), and the motions of the arms are constrained by the physical coupling through the held object. Experimentally measured trajectories of two arms in the coordinated positioning/orienting task are presented. The hypothesis that the rotational and translational components of motions are decoupled and independently planned is tested. Two explicit mathematical models to account for the kinematic features of the two-arm motions are formulated, and the predictions of the models are compared with the experimental data. Both models extend the minimum-jerk model to the two-arm coordinated motions case. The trajectories predicted by the models were found to be in qualitative agreement with the experimental data. However, neither model could account for the observed configuration dependence of the motions, nor for some of the properties of the measured velocity components of the motions. Our findings support the idea that the rotational and translational components of two-arm motions in the positioning/orienting task are independently planned in extra-personal space, and are further combined in a hierarchical fashion to produce the observed motions. The tested models may serve as a basis for further investigations of issues pertinent to the generation of two-arm trajectories.

Arm↗

PubMed1995

Plantaris muscle injury: evaluation with MR imaging.

PURPOSE: To determine the MR imaging appearance of injury to the plantaris muscle. MATERIALS AND METHODS: Fifteen patients with sports-related injuries to the lower leg underwent magnetic resonance (MR) imaging with T1- and T2-weighted, gradient-echo T2*-weighted, short inversion time inversion-recovery, and fast spin-echo sequences. The plantaris muscle and tendon, as well as the surrounding structures, were retrospectively examined for abnormalities. RESULTS: All 15 patients had rupture of the plantaris muscle or strain. An associated torn anterior cruciate ligament (ACL) was found in 10 of 15 patients. Five injuries were isolated or associated with partial tears of the gastrocnemius or popliteus muscle. At initial presentation, three patients had large, focal elongated fluid collections between the medial head of the gastrocnemius muscle and the soleus muscle. CONCLUSION: Rupture of the plantaris muscle may occur at the myotendinous junction with or without an associated hematoma or partial tear of the medial head of the gastrocnemius muscle. A strain of the more proximal plantaris muscle may also occur as an isolated injury or in conjunction with injury to the ACL.

Adult↗

PubMed1994

Posterosuperior glenoid impingement of the shoulder: findings at MR imaging and MR arthrography with arthroscopic correlation.

PURPOSE: To determine the utility of magnetic resonance (MR) imaging and MR arthrography in the evaluation of arthroscopic findings of posterosuperior glenoid impingement. MATERIALS AND METHODS: The findings at MR imaging, MR arthrography, and physical examination with the patient under anesthesia were retrospectively reviewed in eight patients with arthroscopic evidence of posterosuperior glenoid impingement. RESULTS: All patients had shoulder pain; anterior instability was found in six patients. Other than bone marrow abnormalities, findings at MR imaging were not reliable for the detection of posterosuperior glenoid impingement. MR arthrography was superior to routine MR imaging in all four cases in which it was done; positioning the shoulder in abduction and external rotation was beneficial in three of four patients. CONCLUSION: Impingement of the rotator cuff on the posterior superior glenoid labrum is a cause of posterior shoulder pain in athletes who throw. MR arthrography may allow detection of abnormalities associated with this clinical entity.

Adolescent↗

PubMed1993

Tears of the medial collateral ligament: magnetic resonance imaging findings and associated injuries.

For 23 patients with a surgically proven tear of the medial collateral ligament the findings from magnetic resonance imaging (MRI) of the knee were evaluated retrospectively. MRI revealed the tear in all cases, although when the injury was severe, distinguishing high-grade partial tears from complete tears was difficult. Physical examination had indicated a tear in 22 (96%) of the cases. A high prevalence of associated cruciate and meniscal injuries was seen (in 23 [100%] and 12 [52%] of the cases respectively). Tears of the fibular collateral ligament occurred in 13 (57%) of the patients and at least one bony infraction in 22 (96%); most of the infractions were in the lateral compartment. Infractions of the lateral femoral condyle were frequently geographic (in 14 [70%] of the 20 cases) or impacted (in 5 [25%]). The spectrum of injuries associated with tears of the medial collateral ligament was consistent with the findings of previous studies focusing on cruciate and meniscal abnormalities; the minor variations were likely due to the severity of valgus stress in this sample.

Adolescent↗

PubMed1992

Resident training in breast imaging in Canada: current status.

The authors evaluated the current status of resident training in breast imaging in Canada to provide baseline data for guidelines on the amount and the nature of training necessary. Information was obtained, by means of a questionnaire or a telephone interview, from the directors of all 16 radiology residency programs and the 58 radiology residents in their final year at the time of the study. All programs offer training in breast imaging; the training is mandatory in 11 (69%) and elective in 5 (31%). Of the 58 residents, 52 had had some training in breast imaging at the time of the study. Of these, 24 (46%) had spent a period averaging 3.9 weeks exclusively on breast imaging. Forty-one percent of residents felt that the duration of their breast imaging training was too short, and 35% felt that they could not practise mammography independently after their rotation. The authors found that training in breast imaging across the country is highly variable. Although this training is being upgraded in many programs, deficiencies remain. Guidelines are needed to ensure a minimum standard for training in breast imaging.

Biopsy, Needle↗

PubMedDate not supplied

Soft tissue coccidioidomycosis on MRI.

OBJECTIVE: To determine the appearance of soft tissue coccidioidomycosis on MRI. MATERIALS AND METHODS: Two cases of soft coccidioidomycosis with preoperative MR imaging are presented. RESULTS: Prospectively, infection was considered unlikely both clinically and on imaging studies. In retrospect, the MR appearance was nonspecific in one case and suggestive of infection in the other. CONCLUSION: Radiologists should be prepared to entertain coccidioidal abscess as a differential consideration when soft tissue masses are seen on MRI, even when infection is not suggested clinically.

Adult↗