Search PubMed⌕ Search

Biomedical subjects

M R Patel

Publications and source records attributed to M R Patel.

At least 55 records · Page 3Linked to original sources
PubMed1995

Brain lesions in patients with multiple sclerosis: detection with echo-planar imaging.

PURPOSE: To evaluate the detection of brain lesions with echo-planar imaging relative to conventional spin-echo (SE) imaging. MATERIALS AND METHODS: In 17 patients (three men, 14 women; mean age, 31 years) with multiple sclerosis, the following were compared: single-shot proton-density- and T2-weighted and thin-section T2-weighted echo-planar, proton-density- and T2-weighted multishot echo-planar, and conventional SE sequences. Quantitative and qualitative criteria as well as lesion detectability were evaluated. The proton-density-weighted SE sequence was used as the standard of reference. RESULTS: Multishot sequences were superior to single-shot sequences in image quality and lesion detectability. With the multishot proton-density-weighted sequence, 53 of 54 large lesions and 23 of 30 small lesions were detected; with the single-shot proton-density-weighted sequence, 38 of 54 large lesions and five of 30 small lesions were detected. CONCLUSION: With multishot echo-planar sequences, detectability of large lesions is similar to that with conventional SE imaging. Susceptibility artifact is diminished in comparison to single-shot echo-planar sequences.

Adult↗
PubMed1995

Preoperative assessment of the carotid bifurcation. Can magnetic resonance angiography and duplex ultrasonography replace contrast arteriography?

BACKGROUND AND PURPOSE: Noninvasive studies are used with increasing frequency to assess the carotid bifurcation before endarterectomy. Therefore, assessment of their diagnostic accuracies is essential for appropriate patient management. We prospectively evaluate two noninvasive tests, magnetic resonance angiography (MRA) and duplex ultrasonography (DU), as potential replacements for contrast arteriography (CA). METHODS: A blinded comparison of three-dimensional time-of-flight (TOF) MRA, two-dimensional TOF MRA, and DU in 176 arteries was performed. CA was used as the standard of comparison. RESULTS: Three-dimensional TOF MRA had a sensitivity of 94%, a specificity of 85%, and an accuracy of 88% for the identification of 70% to 99% stenosis; two-dimensional TOF MRA had a sensitivity and specificity that were approximately 10% lower than those of three-dimensional TOF MRA. DU resulted in a sensitivity of 94%, a specificity of 83%, and an accuracy of 86%. Combining data from three-dimensional TOF MRA and DU, allowing for CA only for disparate results, yielded a sensitivity of 100%, a specificity of 91%, and an accuracy of 94% among concordant noninvasive tests, with CA required in 16% of arteries. MRA accurately differentiated 17 carotid occlusions from 16 high-grade (90% to 99%) stenoses, whereas with DU two patent arteries were identified as occluded and one occluded artery was identified as patent. CONCLUSIONS: Three-dimensional TOF MRA is the most accurate noninvasive test. Combined use of MRA and DU results in a marked increase in accuracy to a level that obviates the need for CA in a majority of patients.

Aged↗
PubMed1995

Dissection of the carotid and vertebral arteries: imaging with MR angiography.

Arterial dissection occurs when an intimal tear allows blood to enter the arterial wall, potentially compromising the lumen and reducing blood flow. Carotid and vertebral artery dissections typically occur after major trauma, although they also can arise spontaneously or after trivial injury. Arterial dissection has been associated with a variety of factors, including hypertension, fibromuscular dysplasia, Marfan syndrome, cystic medial necrosis, oral contraceptives, drug abuse (sympathomimetics), and infection [1-8]. It is important to recognize arterial dissection early so that prompt treatment can be initiated to prevent ischemic complications [1]. In this essay, we illustrate the use of MR angiography in the diagnosis of carotid and vertebral artery dissection.

Adolescent↗
PubMed1995

MR imaging of diseases of the brain: comparison of GRASE and conventional spin-echo T2-weighted pulse sequences.

OBJECTIVE: The purpose of this study was to compare a combined gradient and spin-echo (GRASE) technique, which is a rapid T2-weighted imaging sequence, with conventional spin-echo (SE) sequences for imaging brain lesions. The GRASE sequences would allow increased patient throughput with potential cost savings and be useful in uncooperative patients without requiring echoplanar imaging techniques and specialized hardware. SUBJECTS AND METHODS: Conventional SE and GRASE T2-weighted images of 49 consecutive patients (20-86 years old) were reviewed independently by three neurora-diologists for the presence and characterization of lesions (most of which were nonspecific foci of hyperintensity within the white matter), gray-white matter differentiation, conspicuity of lesions, and periventricular signal abnormality. The MR studies were performed on a 1.0-T Siemens Magnetom Impact scanner, with the SE images obtained using a TR/TE of 2400/40 and the GRASE images obtained using a TR/effective TE of 4400/110. RESULTS: The number of lesions detected that were 5 mm or larger in maximal diameter did not significantly differ among techniques. For lesions smaller than 5 mm, conventional SE T2-weighted images showed more lesions (p < .01). The SE images were better than the GRASE images for assessing gray-white matter differentiation, conspicuity of lesions, and periventricular signal abnormality. The two hypointense lesions were better assessed on the conventional SE images. CONCLUSION: Although GRASE imaging may be potentially useful for rapid imaging of the brain, our experience shows it has a markedly diminished sensitivity for detecting lesions smaller than 5 mm in diameter. Currently, GRASE imaging should not replace the routine clinical use of conventional SE sequences.

Adult↗
PubMed1995

Diffusion and perfusion imaging techniques.

Diffusion imaging techniques including the Stejskal-Tanner and the stimulated emission of amplitude echoes (STEAM) pulse sequences are discussed. The calculation of apparent diffusion coefficient (ADC) maps is reviewed. The perfusion imaging techniques of blood oxygen level dependent (BOLD) and first pass bolus perfusion techniques as well as the newer technique of echo-planar imaging with signal targeting and altering radiofrequency (EPISTAR) are also discussed. Finally, the theory of intravoxel incoherent motion (IVIM) and its relationship to both diffusion and perfusion phenomena is examined.

Brain Diseases↗
PubMed1995

Stroke and ischemia.

With the introduction of diffusion imaging the diagnosis and acute stroke can be made within minutes of clinical onset. In combination with perfusion imaging, tissue viability can be assessed. The etiology of ischemia can in most cases be investigated by MR angiography. The current applications of these techniques are reviewed, and pitfalls as well as problems in the diagnosis of acute stroke are discussed. With the availability of these techniques, patients can almost instantaneously be approved for pharmacotherapy and monitored and thus clinical outcome potentially can be improved tremendously.

Acute Disease↗
PubMed1994

MR angiography of the carotid bifurcation: artifacts and limitations.

Although conventional angiography has traditionally been the preoperative study of choice before carotid endarterectomy, alternative noninvasive methods, particularly MR angiography, are being used increasingly for evaluation of the carotid bifurcation [1, 2]. In this essay, we illustrate the limitations of and artifacts associated with two-dimensional (2D) and three-dimensional (3D) time-of-flight (TOF) MR angiography vs conventional angiography when assessing disease of the carotid bifurcation.

Artifacts↗
PubMed1994

Distraction method for chronic dorsal fracture dislocation of the proximal interphalangeal joint.

The authors used gradual ligamentous distraction for closed reduction of nine irreducible dorsal fracture dislocations of the PIP joint. The volar fragment size was equal to or less than 40% in five and more than 50% in four. The average follow up was 18 months. The sequence of treatment required distraction, translation, and joint flexion. Overdistraction by approximately 2 mm was necessary to get sufficient soft tissue lengthening. This allowed adequate joint flexion for concentric joint reduction. Distraction and simultaneous mobilization restored the final range of motion earlier than distraction and subsequent mobilization. The final range of motion of the PIP and DIP joints was from 12 degrees to 91 degrees and 0 to 45 degrees respectively.

Adult↗
PubMed1993

Lionfish envenomation of the hand.

Lionfish (Pterois volitans) envenomation of the hand causes excruciating pain and occurs in three grades: (1) erythematous reaction, (2) blister formation, and (3) dermal necrosis. The initial treatment in all cases is to soak the hand in nonscalding water (45 degrees C) until the pain subsides by denaturing the thermolabile venom proteins. The blisters should be immediately excised to prevent dermal necrosis, inasmuch as the blister fluid contains residual active venom. To prevent a hypersensitivity reaction, any further contact with the fish should be avoided.

Adult↗
PubMed1993

Preoperative diagnosis of a forearm peripheral schwannoma.

A 34-year-old man had a right distal forearm mass of unknown etiology for 6 years. Magnetic resonance imaging showed a tumor in continuity with the median nerve. Fine-needle biopsy revealed it to be a schwannoma. Surgical excision was performed by separating the nerve fascicles from the tumor. The patient was asymptomatic at 12-month follow-up.

Adult↗
PubMed1992

Trigger fingers and thumb: when to splint, inject, or operate.

Fifty trigger fingers were treated by splinting of the metacarpophalangeal joint at 10 to 15 degrees of flexion for an average of 6 weeks (range, 3 to 9 weeks). Another 50 trigger fingers were injected with 0.5 ml of betamethasone sodium phosphate and acetate suspension (Celestone) and 0.5 ml of lidocaine. All patients were followed up for a minimum of 1 year (range, 1 to 4 years). Treatment was successful in 33 (66%) of the splinted digits and 42 (84%) of the injected digits. Fifty percent of the 10 splinted thumbs and 70% of the 40 splinted fingers had a successful outcome. Of the 17 unsuccessfully treated digits in the splinted group, 15 were later cured with injections and 2 required surgery. All of the 7 unsuccessfully treated digits in the injected group were cured with surgery. Patients with marked triggering, symptoms of more than 6 months' duration, and multiple involved digits had a higher rate of failure in both groups. Splinting offers an alternative for patients who have a strong objection to cortisone injection.

Cortisone↗
PubMed1990

Fractures of the sesamoid bones of the thumb.

Sesamoid fractures of the metacarpophalangeal joint of the thumb may be classified into two types: (1) with palmar plate intact, and (2) with palmar plate ruptured. In type 1, the patient maintains a normal flexion posture of the metacarpophalangeal joint as well as the ability to flex the metacarpophalangeal joint and interphalangeal joint. In type 2, the metacarpophalangeal joint assumes a hyperextension posture and the patient is unable to flex the metacarpophalangeal joint. Three cases are described to illustrate the two types of the injury. An open fracture of a thumb sesamoid associated with laceration of the palmar plate in a child was treated by reapproximating the palmar plate and the fracture fragments with sutures. Two additional closed fractures of the thumb sesamoid were treated by splinting the metacarpophalangeal joint in comfortable flexion for 2 to 3 weeks. Normal hand function was restored in all the three patients.

Adolescent↗
PubMed1989

Subungual keratoacanthoma in the hand.

A subungual keratoacanthoma of the thumb with a 5-year follow-up is reported. Recurrence after initial curettage necessitated amputation of the terminal phalanx as definitive treatment. The 22 subungual keratoacanthomas of the hand reported in the literature are reviewed. Although conservative treatment sparing the digit in the form of excision and curettage is recommended as the initial treatment of choice, this uncommon benign, but aggressive, lesion of the nail bed may require amputation of the involved phalanx as definitive treatment.

Amputation, Surgical↗
PubMed1989

Painful extensor digitorum brevis manus muscle.

Diagnosis was confirmed of 10 extensor digitorum brevis manus muscles in 7 patients. The muscle is located on the dorsum of the hand, just distal to the wrist. It is most prominent with the wrist flexed to 30 degrees and the fingers fully extended. We propose that pain in the extensor digitorum brevis manus muscle is due to compression of the muscle in the rigid fibro-osseous fourth dorsal compartment. Extensor retinacular release is the treatment of choice.

Adult↗