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Biomedical subjects

J L Fleckenstein

Publications and source records attributed to J L Fleckenstein.

At least 37 records · Page 2Linked to original sources
PubMed1996

Inflammatory myopathies: radiologic evaluation.

Clinical evaluation of skeletal muscle in patients with inflammatory myopathies (IM) has long been hampered by difficulty in assessing the morphology and functional integrity of skeletal muscles. Advances in radiologic techniques, particularly MR imaging, have improved the ability to manage patients with neuromuscular disease in general and IM in particular. MR imaging can probe beyond the skin to identify focal muscle structural lesions, determine their extent, characterize their composition, direct invasive procedures, and monitor therapies. This article reviews the clinical, pathologic, and imaging aspects of these diseases.

Adult↗
PubMed1996

Central nervous system lymphoma not detectable on single-photon emission CT with thallium 201.

A 33-year-old man with acquired immunodeficiency syndrome had an erosive supraglottic mass visible on CT scans of the neck; biopsy was postponed because of the patient's debilitated condition. Two weeks later, he was admitted with altered mental status; an MR image of the brain obtained at that time showed multiple bilateral mass lesions, the largest of which was 5 cm. Findings on a thallium-201 single-photon emission CT (SPECT) scan of the brain were normal. Ten days later, the patient died and autopsy showed both the neck and the brain lesions to be large-cell lymphoma. This case is counterevidence to the reported 100% sensitivity of thallium-201 brain SPECT for demonstrating lymphoma of the central nervous system.

Adult↗
PubMed1995

High-voltage electric injury: assessment of muscle viability with MR imaging and Tc-99m pyrophosphate scintigraphy.

PURPOSE: To evaluate use of magnetic resonance (MR) imaging and technetium-99m pyrophosphate (PYP) scintigraphy in preoperative assessment of muscle viability after high-voltage electric injury. MATERIALS AND METHODS: Twelve injured limbs were studied. Immediate, equilibrium, and delayed Tc-99m PYP scintigrams and gadolinium-enhanced and unenhanced MR images were obtained. Imaging results were compared with clinical findings. RESULTS: Scintigraphy demonstrated nonperfusion in four limbs that were subsequently amputated, but MR imaging had poor sensitivity in nonperfused regions owing to lack of edema. Tc-99m PYP uptake increased at transition zones between normal and nonperfused regions. MR imaging allowed further characterization of these zones by demonstrating edema as enhancing (perfused) or nonenhancing (nonperfused). In all nonamputated limbs, edema showed enhancement. CONCLUSION: In high-voltage electric injury, gadolinium-enhanced MR imaging appears able to demonstrate zones of potential viability within radionuclide-avid tissue but has poor perfusion sensitivity when used alone.

Amputation, Surgical↗
PubMed1995

Muscle weakness and myalgia. MR imaging investigation.

The status of muscle integrity need no longer be surmised on the basis of gross clinical assessments of muscle strength and invasive procedures. MR imaging brings to the clinical arena new capabilities to aid the management of patients with common muscle complaints of common and uncommon causes. Although findings on MR imaging tend to be nonspecific, muscle structural lesions can be defined in terms of extent and gross composition, and thus help direct invasive procedures and monitor therapies. Radiologists need to remember that their observation of muscle lesions on MR imaging may be the serendipitous discovery of the true cause of a patient's compliant.

Diagnosis, Differential↗
PubMed1994

Magnetic resonance imaging of skeletal muscles in idiopathic inflammatory myopathies of adults.

The purpose of the study was to describe typical MRI findings in various types of idiopathic inflammatory myopathies in adulthood and to correlate the MRI with histopathological and electromyographic findings, and the serum creatine kinase (CK) activity. A third goal was to assess the diagnostic value of the use of gadolinium-DTPA (Gd-DTPA). Fifty-eight patients (35 women, 23 men), aged 21-83 years (median age 59 years), suffering from idiopathic myositides (13 with acute and 45 chronic diseases; 25 with polymyositis, 14 with dermatomyositis, 8 with granulomatous and 11 with inclusion body myositides) were examined with MRI. Seventeen of them received an intravenous infusion of Gd-DTPA. Histopathological and MRI findings of 21 muscles of 18 patients were compared. MRI of skeletal muscles showed abnormal signal intensities in 56 (96.6%) of the 58 patients. MRI abnormalities were found more often than elevated CK activity (P < 0.001). The hyperintensity of T2-weighted images was more conspicuous than on T1-weighted images in 26 (44.8%) patients, indicating oedema-like abnormalities. MRI of 50 (86.2%) patients showed fat replacement. In acute myositides, oedema-like abnormalities were more often visible and in muscle lipomatosis less often visible than in chronic diseases (P < 0.05 each). In dermatomyositis oedema-like abnormalities were more and lipomatosis less frequent than in the other types of myositis (P < 0.005) and correlated with the acuteness of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Muscular ultrasound in idiopathic inflammatory myopathies of adults.

To evaluate the value of myosonography in inflammatory myopathies ultrasound of skeletal muscles was performed in 70 patients, aged 21-82 years, suffering from histologically proven polymyositis (n = 30), dermatomyositis (n = 18), granulomatous myositis (n = 9), inclusion body myositis (n = 13), and in 102 control persons. The sensitivity of muscle ultrasound in detecting histopathologically proven disease (82.9%) was not significantly different from electromyography (92.4%) or serum creatine kinase activity (68.7%). The positive predictive value of ultrasound was 95.1%, the negative predictive value 89.2%, and the accuracy 91.3%. The different types of inflammatory myopathies presented with typical, but not specific ultrasound features. Polymyositis showed atrophy and increased echointensity predominantly of lower extremity muscles, whereas in dermatomyositis clear muscle atrophy was rare and echointensities were highest in forearm muscles. Echointensities were lower in dermatomyositis compared to poly- and granulomatous myositis. Granulomatous myositis was characterized by the highest echointensities and a tendency towards muscle hypertrophy. Severe muscle atrophy was the most impressive feature in the majority of patients with inclusion body myositis. Comparison of ultrasound and histopathological findings indicates that muscle lipomatosis has a much greater impact on muscular echointensity than does muscle fibrosis. Ultrasound of myositis improved clinical assessment of patients by supplying differential diagnostic clues based on precise muscle size measurements and identification of mesenchymal abnormalities, particularly muscle lipomatosis.

Adult↗
PubMed1993

MRI-guided biopsy in inflammatory myopathy: initial results.

The purpose of this report is to describe our initial experience with techniques employing magnetic resonance imaging (MRI) to guide the choice of muscle to be biopsied in patients suspected of having inflammatory myopathy. Five patients with a clinical diagnosis of inflammatory myopathy (IM) were studied. Four were imaged prior to biopsy. Four had repeated examinations, either immediately following biopsy or to evaluate disease progression. Use of MRI to localize muscle lesions was associated with abnormal pathologic findings in all cases, including histopathologic demonstration of lymphocyte infiltration in three cases of idiopathic polymyositis; nonspecific myopathic changes were seen in one patient with probable dermatomyositis and in one patient with chronic inflammatory polyneuropathy and high serum creatine kinase levels (> 45,000 IU/ml). The precise location of the area sampled by biopsy was visible in only one of four postbiopsy images. MRI shows promise in identifying pathologic muscle in patients suspected of having one of the inflammatory myopathies; however, further refinement of localization techniques may be needed to optimize histopathologic diagnoses.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Lumbar muscle usage in chronic low back pain. Magnetic resonance image evaluation.

Methods for detecting recruitment patterns of the lumbar muscles during exercise in patients with chronic low back pain are limited. This article discusses the use of magnetic resonance imaging with Roman chair extension exercise to examine lumbar muscle usage in five normal volunteers, five chronic low back pain patients without surgery, and five chronic low back pain patients with surgery. Changes in signal intensities of psoas, multifidus, and longissimus/iliocostalis with graded exercise were measured at three lumbar disc levels. At rest, there was a difference between multifidus and longissimus/iliocostalis signal intensity in chronic low back pain subjects without surgery (P = 0.0162) and in chronic low back pain subjects with surgery (P = 0.0036), but not in normal subjects. At peak exercise, there was a difference in signal intensities between multifidus and longissimus/iliocostalis in all groups (normal volunteers, P = 0.0069; chronic low back pain patients without surgery, P = 0.0125; chronic low back pain patients with surgery, P = 0.0060). The exercise response was attenuated in chronic low back pain patients with surgery. Thus, MRI demonstrates static and dynamic differences in lumbar paraspinal musculature in chronic low back pain subjects compared to normal subjects.

Exercise↗
PubMed1993

Human immunodeficiency virus infection: musculoskeletal manifestations.

The authors retrospectively reviewed the charts, radiographs, and other accompanying imaging studies of 45 patients with musculoskeletal abnormalities associated with human immunodeficiency virus (HIV) infection. These included 19 patients with osseous infection, including eight with osteomyelitis, seven with bacillary angiomatosis (six of whom were described in a previous report), and four with septic arthritis; 10 with bacterial myositis (six of whom were described in a previous report); seven with non-Hodgkin lymphoma; five with hypointense marrow signal intensity at magnetic resonance imaging; two with Kaposi sarcoma; one with polymyositis; and one with psoriasis. The musculoskeletal system can be affected by a variety of abnormalities in association with HIV infection. Knowledge of their existence and characteristic appearance is valuable to radiologists for diagnosis and to clinicians for detection and appropriate treatment.

AIDS-Related Opportunistic Infections↗
PubMed1993

Denervated human skeletal muscle: MR imaging evaluation.

Because determination of neurologic integrity after severe limb trauma is crucial in patient care, the authors assessed magnetic resonance (MR) imaging as a tool to map denervated motor units of skeletal muscle in patients with traumatic peripheral neuropathy. Denervation was confirmed in 22 patients with use of electromyography, surgery, or both. MR imaging was performed with moderately T1- and T2-weighted spin-echo and short-tau inversion-recovery (STIR) sequences. MR imaging was unreliable in depicting acute denervation. Muscles of patients with subacute denervation had prolonged T1 and T2, which contributed to conspicuous hyperintensity on STIR images. Chronically denervated muscles showed marked atrophy, variable changes on STIR images, and conspicuous fatty infiltration on T1-weighted images. Normal variants in motor unit anatomy were seen in denervated muscle volumes outside the expected distribution of the injured nerve. MR imaging is promising for the noninvasive mapping and monitoring of denervated muscle in subacute and chronic phases of peripheral neuropathy.

Extremities↗
PubMed1993

Muscle proton T2 relaxation times and work during repetitive maximal voluntary exercise.

We studied the effects of progressive maximal voluntary handgrip contractions (MVCs) on muscle proton spin-spin (T2) relaxation times and work, measured as the integrated force vs. time curve (FTI). Six healthy volunteers performed 10, 20, 40, and 80 MVCs in a 0.35-T magnet on four separate occasions. Repeated measures analyses of variance of increases in T2 and FTI during successive bouts were significant (P < 0.005 and P < 0.001, respectively). FTI increased with successive bouts to a greater extent than did muscle T2 (P < 0.05). For T2, the Helmert contrast judged the 10-MVC response lower than the mean of the remaining responses (P < 0.005), and the differences between all others compared with the means of subsequent responses were not significant, indicating a "flattening" of the T2 response after the increase from 10 to 20 repetitions. For FTI, all the single degree of freedom Helmert contrasts were significant (P < 0.001), indicating a continual increase in response over increased MVCs. The curved nature of the T2 response conformed best to a hyperbolic function, suggesting that a limit of approximately 32% exists for the change in T2 during progressively longer bouts of MVCs. A limit in the T2 response is consistent with the existence of a limit in the amount of water that muscle can take up from the vasculature during exertion.

Adult↗
PubMed1992

MRI evaluation of amyloid myopathy.

Amyloid myopathy is a rare complication of primary amyloidosis. The magnetic resonance imaging (MRI) features of two patients with amyloid myopathy were studied. Slight prolongation of muscle T1 and T2 relaxation times was evident but the striking abnormality was marked reticulation of the subcutaneous fat. The clinical findings of indurated extremities far exceeds the minimal signal intensity alteration seen in the muscles. The MR appearance of amyloid myopathy differs from that of other neuromuscular conditions in the minimal changes found in muscle, but the striking abnormality seen in subcutaneous fat makes it distinct from many neuromuscular conditions.

Amyloid↗
PubMed1992

The skeleton in congenital, generalized lipodystrophy: evaluation using whole-body radiographic surveys, magnetic resonance imaging and technetium-99m bone scintigraphy.

Congenital generalized lipodystrophy (CGL) is a rare genetic disease characterized by the absence of body fat from birth. Focal bone lesions have also been reported, but their pathophysiology is poorly understood. To characterize skeletal abnormalities further in 3 patients with CGL, we employed whole-body radiographic skeletal surveys, magnetic resonance imaging (MRI, including gadolinium enhancement), and triple phase technetium-99m methylene diphosphonate bone scintigraphy. Radiographs showed numerous focal lesions within the long bones, as described in other reports. MRI showed that the entire marrow space of the long bones was abnormal and was characterized, at least in part, by the absence of marrow fat. Prolonged T1 and T2 times and marked gadolinium enhancement were observed in radiographically normal-appearing long bone. Radiographically lytic lesions occasionally demonstrated fluid-fluid levels on MRI and enhanced peripherally after gadolinium infusion. Bone scintigraphy findings such as periarticular hyperemia were relative subtle. We conclude that the appendicular skeleton of patients with CGL is diffusely abnormal and is predisposed to focal osteolysis and cyst formation.

Adult↗
PubMed1992

Skeletal muscle lymphoma: MRI evaluation.

The magnetic resonance imaging (MRI) features of two cases of malignant lymphoproliferative disease involving skeletal muscle are presented. In both cases involved muscles were quantitatively and subjectively hypointense to fat on T1-weighted spin echo images, hypointense or isointense on T2-weighted spin echo images, and hyperintense on short tau inversion recovery (STIR) images. The findings suggest that lymphoproliferative disease should be considered as an etiology of a skeletal muscle lesion that is hypointense or isointense to fat on T2-weighted spin echo magnetic resonance images.

Adult↗