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Biomedical subjects

P C Hajek

Publications and source records attributed to P C Hajek.

At least 19 recordsLinked to original sources
PubMed1990

The effect of intra-articular gadolinium-DTPA on synovial membrane and cartilage.

This investigation evaluated the potential effect of gadolinium (Gd)-DTPA-dimeglumine on synovial membrane and joint cartilage, using macroscopic, microscopic, and x-ray fluorescent spectroscopic techniques. Thirteen New Zealand white rabbits (26 knees) were used in this study, ten receiving 500 micromolar injections of Gd-DTPA-dimeglumine in their right knees; the remainder of the knees served as controls. One injected knee had minimal joint effusion and one had mild hyperemia. Microscopically four knees exhibited mild focal hyperplasia of the synovium, another three minimal focal mononuclear cell infiltration. X-ray fluorescent spectroscopy demonstrated no evidence of Gd-DTPA-dimeglumine in the synovium or articular cartilage. Neither macroscopic nor microscopic evaluation detected any Gd-DTPA-dimeglumine related effects. Gd-DTPA-dimeglumine was found to be safe for intra-articular injection in this animal model.

Animals↗
PubMed1989

Fibrous metaphyseal defects. Magnetic resonance imaging appearances.

Sixteen patients with fibrous metaphyseal defects were examined with both plain radiography and magnetic resonance (MR) imaging. Depending on the age of the fibrous metaphyseal defects, characteristic radiomorphologic changes were found which correlated well with MR images. Following intravenous Gadolinium-DTPA injection, fibrous metaphyseal defects invariably exhibited a hyperintense border and signal enhancement. Healed lesions exhibited a transition to normal bone marrow. A line through the maximum longitudinal diameter of a fibrous metaphyseal defect invariably led to a point of tendinous or ligamentous insertion. Coronal MR images demonstrated the maximum longitudinal extension and the respective inserting tendon or ligamentous structure at the epiphyseal line.

Adolescent↗
PubMed1989

Carpal tunnel syndrome: morphologic changes after release of the transverse carpal ligament.

We describe the morphologic changes that follow division of the transverse carpal ligament in patients with carpal tunnel syndrome. Fifteen hands in 12 patients with carpal tunnel syndrome were studied with magnetic resonance imaging before operation and for 6 weeks after operation. Eight hands were studied at 8 months after operation. Carpal arch width, anterior displacement of the carpal canal contents, and carpal canal volume were measured by use of multiplanar reformation and three-dimensional reconstruction of magnetic resonance images. There was a 24.2 +/- 11.6% increase in carpal canal volume 6 weeks after carpal tunnel release (p less than 0.001). This difference persisted at 8-month follow-up. There was an anterior displacement of carpal canal contents 3.5 +/- 1.9 mm from its original position 6 weeks after operation (p less than 0.001). This palmar displacement persisted at the 8-month follow-up. There was no statistically significant increase in carpal arch width 8 months after carpal tunnel release. We believe that division of the transverse carpal ligament restores median nerve function by increasing the volume of the carpal canal. This volumetric increase results from an anterior displacement of the newly formed transverse carpal ligament and not from a widening of the bony carpal arch.

Carpal Bones↗
PubMed1989

[Intratemporal course of the facial nerve in magnetic resonance imaging].

MR images of the intratemporal portion of the facial nerve were obtained with a 1.5 Tesla permanent magnet whole-body imaging system. The facial nerve was followed from the internal auditory through the temporal bone to the styloid foramen. MR promises to be a sensitive method for the evaluation of intratemporal facial nerve diseases.

Facial Nerve↗
PubMed1988

[Magnetic resonance tomography as a localization method in hyperparathyroidism].

Magnetic Resonance Imaging (MRT) was performed in 36 consecutive patients with hyperparathyroidism. MR tomograms of 31 patients were evaluated and compared with the results of operation and histology (n = 29). In the remaining 5 patients MR examination was not completed, due to claustrophobia or motion artefacts. MR examinations were performed in 2 superconductive magnets (0.5 and 1.5 Tesla). A surface coil with following spinecho sequences was used: SE: TR/TE: 550-700/15-30; 2000/22-100. All patients were subjected to additional sonography. Out of 28 parathyroid adenomas 25 were identified on MR tomograms (sensitivity: 73%, specificity: 90%). However, only 2 out of 6 hyperplastic parathyroid glands were localized on MR tomograms. Lesions missed on MR tomograms measured 15 mm and less in diameter. It is characteristic that parathyroid adenomas showed isointense MR signal to the thyroid (SE 550/30 and hyperintense MR signal to fat (SE 2000/100). Different signal intensities of the adenomas were observed in 25% of the cases. MR imaging is a valuable diagnostic method for preoperative localisation of parathyroid adenomas. We think that MR imaging should be performed when sonography and subtraction scintigraphy are not able to identify a suspected adenoma in the same location.

Adenoma↗
PubMed1988

Skeletal involvement in hairy cell leukemia.

The clinical and radiographic aspects of two patients with destructive bone lesions, complicating the course of hairy cell leukemia are presented. The findings are compared with those of 27 previously published cases. The most prominent features of this rare skeletal disorder are osteolysis and widespread or localized demineralisation with predilection for the femoral head and neck. Localized persisting pain is the leading clinical symptom in all cases. Magnetic resonance imaging is helpful in evaluating the extent of bone marrow infiltration and demonstrates focal areas of decreased signal intensity in sites of radiographically detectable bone destruction as well as in bones that appear normal on plain films.

Bone Neoplasms↗
PubMed1988

[Focal fatty deposits in spinal bone marrow--MR findings. MRI of focal fatty deposits].

MR tomograms of the spines of 121 patients were reviewed in order to assess the incidence and distribution of focal fat deposits in axial bone marrow. In addition, three cadaver spines were examined and cut with a band saw for macroscopic and histologic correlation. Yellow areas, histologically representing fatty replacement of hematopoetic marrow, were found macroscopically; their location was in precise correspondence to areas of focal enhanced signal intensity on T1-WI as well as T2-WI. The incidence of those focal fat spots was related to age, but not to sex; in different diseases like scoliosis, porosis and after cytostatic therapy of different malignomas they were found more frequently than in the average of the sample. Focal fatty replacement of hematopoetic bone marrow is obviously a normal phenomenon and should not be misinterpreted as a pathologic condition.

Bone Marrow Diseases↗
PubMed1988

Magnetic resonance imaging of the lower vertebral column in patients with multiple myeloma.

Eighteen patients with multiple myeloma (clinical stages 1-3) and a control group of 21 persons underwent magnetic resonance imaging (MRI) studies of the lower thoracic and lumbar spine. This was done to determine the potential benefit of MRI in addition to conventional radiographs, tomograms, computed tomography and nuclear scans. In addition to focal fatty replacement of normal hematopoietic marrow, which presented as focal hyperintense lesions on T1-weighted images (T1-WI) and on T2-weighted images (T2-WI), two types of myelomatous lesions were found: (1) focal areas with reduced signal intensity when compared with normal bone marrow on T1-WI and enhanced signal intensity on T2-WI, mainly found in untreated myelomas; and (2) focal areas of decreased signal intensity on T1-WI and on T2-WI, which were predominantly detected after previous radiation therapy. MRI surpassed conventional radiography in detecting abnormal focal marrow infiltration in 41 of 247 vertebrae. Radiographs identified only 11 of the 41 as pathologic, based on shape and structure of the vertebral bodies; however, 15 other collapsed vertebrae showed no signal abnormalities of the marrow on MR images. Discrimination of normals and abnormals by statistical analysis of intensity measurements of the bone marrow was not possible.

Adult↗
PubMed1987

Obesity and decreased femoral anteversion in adolescence.

The degree of femoral anteversion in a group of obese adolescent children and a group of adolescent children of normal weight was determined by either magnetic resonance imaging or computerized axial tomography. Compared with the children of normal weight, the obese children showed a significantly reduced angle of femoral anteversion. Increased biomechanical forces generated across the hip joint of obese children leads to increased remodeling of the femoral neck. This may account for the association of slipped capital femoral epiphysis, reduced femoral anteversion, and obesity in the adolescent population.

Adolescent↗
PubMed1987

Magnetic resonance imaging of glenohumeral joint diseases.

Through the application of oblique planes and flexible surface coil techniques, magnetic resonance imaging (MRI) promises to be of great clinical value in the evaluation of a variety of pathologic conditions affecting the shoulder. In patients with joint effusions, the tendinous portion of the rotator cuff, glenoid labrum, and bicipital tendon can be readily visualized. This capability has particular relevance in patients with inflammatory disease and traumatic conditions. Rotator cuff atrophy and impingement of the coracoacromial arc upon the supraspinatus muscle and tendon can also be demonstrated. MRI is also useful in the evaluation of shoulder instability.

Humans↗
PubMed1987

High-resolution magnetic resonance imaging of the wrist: normal anatomy.

Magnetic resonance imaging (MRI) provided adequate depiction of carpal soft tissue structures in normal volunteers, as well as accurate anatomic correlation with cadaveric specimens. Using a high field strength system and surface coil techniques, the intricate anatomy of the wrist was best defined on long TR short TE images. However, from a practical view, T1 weighted images (TR 600 ms, TE 25 ms) were most useful because of short imaging times, satisfactory image quality, and the absence of motion artifacts. The coronal plane provided the clearest definition of important structures. Potential diagnostic limitations exist due to the inability of MRI to clearly delineate articular cartilage, joint capsules, and small interosseous ligaments. The presence of intra-articular fluid in both living subjects and cadaveric specimens, however, allowed for fine depiction of these structures on T2 weighted images.

Humans↗
PubMed1987

Carpal tunnel volume determination by magnetic resonance imaging three-dimensional reconstruction.

Three-dimensional computer reconstruction of magnetic resonance images (MRI) of ten cadaveric specimens was used to determine carpal tunnel volume and carpal arch width. Magnetic resonance images-acquired data were compared with direct measurement of cadaveric carpal canal volume by means of a silicone-injection technique. Mean MRI three-dimensional reconstruction volume was 5.84 ml +/- 1.24 ml. Mean silicone-mold volume was 4.73 +/- 1.01 ml. A correction factor of 0.8161 was used to accurately calculate carpal tunnel volume from MRI-acquired data. There was no significant difference between calculated carpal tunnel volumes and silicone-mold volumes (p = 0.623), and there was a linear relationship between MRI-acquired volumes and silicone-mold volumes (correlation coefficient r = 0.97). Differences in MRI-volume determinations between observers were not significant (0.25 greater than or equal to p greater than 0.1). MRI three-dimensional reconstruction, a valid and reproducible technique for measuring carpal tunnel volume and dimensions, has considerable research potential for the evaluation of the relationship between the carpal canal and its contents before and after carpal tunnel release.

Carpal Bones↗
PubMed1987

The high signal intensity meniscus of the knee. Magnetic resonance evaluation and in vivo correlation.

This study describes the different appearances of meniscal abnormalities on magnetic resonance (MR) images and correlates macroscopic and histologic findings. Twenty-three of 40 cadaveric menisci with MR signal abnormalities were examined macroscopically; five of the 23 were studied histologically. In addition, MR studies of seven patients (14 menisci) were examined and findings were correlated arthroscopically. Histologic analysis was performed on two of these menisci. The two major findings on MR images were: (1) abnormal, high, centrally located signal intensity within the meniscus and (2) disruption of the peripheral meniscal contour. Macroscopically evident meniscal degeneration correlated well with findings on MR images in all cases. Histologic abnormalities included microcyst formation and separation of collagen bundles. Four menisci with intact outer contour lines on MR images had macroscopically identifiable tears. In addition, two meniscal tears were appreciated only after intra-articular injection of gadolinium-DTPA. We conclude that MR imaging is superior to macroscopic examination as performed by arthroscopy or arthrotomy for the detection of degenerative meniscal lesions. The technique also accurately identifies meniscal tears, a capability that might be enhanced by prior intra-articular injection of MR contrast agents.

Adult↗
PubMed1987

Focal fat deposition in axial bone marrow: MR characteristics.

One hundred fifty-eight magnetic resonance (MR) imaging studies of the spine were reviewed to assess the frequency and distribution of focal deposits with signal behavior typical of fat in the axial bone marrow. In addition, three fresh cadaveric spines were evaluated with MR imaging and subsequently sectioned for anatomic and histologic correlation. Macroscopic evaluation of the sectioned cadaveric specimens revealed well-defined, yellow areas within the bone marrow that correlated precisely with localized zones of signal intensity characteristic of fat on MR images. Histologic evaluation of these regions demonstrated typical focal fatty replacement of hematopoietic bone marrow. Their appearance was related to age and the presence of pathologic changes such as spondylitis, kyphoscoliosis, and spondylosis. Based upon these observations, focal fatty replacement of hematopoietic bone marrow appears to be a common phenomenon that should not be confused with localized disease processes.

Adipose Tissue↗
PubMed1987

MR arthrography: anatomic-pathologic investigation.

To enhance the efficacy of magnetic resonance (MR) imaging in evaluating articular soft-tissue structures, arthrography was performed before imaging 45 fresh cadaveric specimens. Contrast agents used were gadolinium-DTPA, 0.9% saline, diatrizoate, and air. MR imaging was performed with and without intraarticular contrast material, and specimens were subsequently sectioned in the same plane. Gd-DTPA was the most effective agent. Saline and diatrizoate exhibited equivalent signal behavior and necessitated T2-weighted sequences, while air was not useful. Depiction of normal anatomy was enhanced with MR arthrography. After surgical creation of lesions in selected specimens, subtle tears were delineated exclusively with MR arthrography, and major tears were diagnosed more confidently. Intraarticular contrast material may enhance the diagnostic capabilities of MR imaging in the setting of joint disease.

Air↗
PubMed1987

MR imaging of the scrotum: normal anatomy.

High-resolution magnetic resonance (MR) imaging with a surface coil was utilized to evaluate the normal scrotum. Scrotal contents, spermatic canal, and inguinal regions were visualized within the same field of view. Differences in signal intensity in the testis, epididymis, tunica albuginea, fluid, fat, and spermatic cord allowed for clear delineation of these structures in detail. The high contrast and spatial resolution of MR imaging, coupled with the wide field of view and absence of ionizing radiation, make MR imaging well suited for evaluation of the scrotum.

Adult↗
PubMed1987

MR imaging of the scrotum: pathologic conditions.

The utility of high-resolution magnetic resonance (MR) imaging in studying a variety of intratesticular and extratesticular pathologic conditions was assessed. The high magnetic signal intensity of the testis provided an excellent background for visualization of intratesticular abnormalities. Except for old blood, all intratesticular processes were less intense than testis, especially on T2-weighted images. The visualization of the tunica albuginea is a distinct advantage, allowing its assessment in cases of trauma or testicular tumors. Epididymal and spermatic cord abnormalities were easily recognized. All pathologic conditions were best seen on T2-weighted images acquired in the coronal plane. Balanced images allowed for tissue characterization.

Genital Diseases, Male↗