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Biomedical subjects

C A Helms

Publications and source records attributed to C A Helms.

At least 91 records · Page 5Linked to original sources
PubMed1987

High resolution computed tomography of knee menisci.

Sixty four menisci in 22 patients were examined by non-contrast high resolution computed tomography (CT). Fifty four menisci were imaged on a GE 8800 CT scanner. The other 10 were imaged on a GE 9800 CT scanner. Nineteen menisci were shown to be torn on arthrography and/or arthroscopy--12 medially and 7 laterally. The remaining menisci were normal. When the meniscal CTs were reviewed collectively by three observers without knowledge of arthrographic or arthroscopic results, sensitivity was 63%, specificity was 93%, and accuracy was 84%. Although only 10 menisci were imaged on the GE 9800 scanner, the sensitivity in this subset of scans was 83%, the specificity 100%, and the accuracy was 90%. These results suggest that noncontrast CT cannot replace arthrography or arthroscopy, but it is possible that images obtained on the GE 9800 or comparable CT scanner may be accurate enough to be used for screening of meniscal tears in selected patients.

Adult↗
PubMed1987

Computed tomography and plain film appearance of a bony sequestration: significance and differential diagnosis.

Bony sequestration has been reported in osteomyelitis, eosinophilic granuloma, and fibrosarcoma. Thirty-eight examples of radiographically apparent bony sequestra were collected to examine the validity of this differential diagnosis. Apparent sequestra were found in osteomyelitis (59%), fibrosarcoma or fibrosarcoma-like entities (13%), eosinophilic granuloma (8%), and osteoid osteoma (21%). Although osteoid osteoma does not contain a true bony sequestrum, the partially calcified nidus was radiographically mistaken for a sequestrum in eight (21%) of our cases and, therefore, should be considered when an apparent sequestrum is visualized. Computed tomography enhanced visualization of a sequestrum in 19 of 22 cases and is recommended as an adjunct to conventional radiography when the presence of a sequestrum will alter therapy.

Bone Diseases↗
PubMed1987

The widened teardrop distance: a plain film indicator of hip joint effusion in adults.

The teardrop distance is defined as the distance from the lateral margin of the pelvic teardrop to the most medial aspect of the femoral head as seen on anteroposterior pelvic radiographs. The structure responsible for the teardrop is the anteroinferior portion of the acetabular fossa with contributions from the ischium and from the superior pubic ramus. Anteroposterior pelvic radiographs of 10 patients with documented cases of unilateral hip effusion were retrospectively evaluated for teardrop distance widening on the affected side. Proof of the presence of hip effusion was based on the results of percutaneous hip joint aspirations as described in the patient's medical records. A teardrop distance widening of 1 mm or more was always consistent with hip joint fluid. In addition, radiographs from 20 patients with no known hip abnormalities were reviewed as a control population. These showed side-to-side symmetry in 16 cases (80%) and widening of less than 1 mm in the remaining four cases (20%). Thus, hip joint effusion in adults can be accurately diagnosed from plain radiographs in the presence of a teardrop asymmetry of 1 mm or more and in the absence of degenerative joint disease.

Adolescent↗
PubMed1987

Osteoid osteoma. The double density sign.

Occasionally, osteoid osteoma can be difficult to radiographically differentiate from osteomyelitis. The precise localization of the nidus of an osteoid osteoma often can be difficult using nothing more than conventional radiographs. In a series of 35 patients, a radionuclide and double density sign facilitated localization of the nidus, confirmed the diagnosis, and aided the surgeon in excision biopsy. This series of cases demonstrates how computed tomography (CT) scanning can more precisely localize the nidus in areas deep in complex joints such as the hip. Fifteen cases of osteoid osteoma were studied with Tc-99m-MDP radionuclide bone scan. Each one exhibited the double density sign. Seven of these patients had CT scans in addition for further localization of the nidus. All were excised with accurate localization of the nidus, and thereby reduced morbidity and postoperative recovery time.

Bone Neoplasms↗
PubMed1986

Oblique head position in temporomandibular joint arthrography.

Thirteen patients were prospectively studied with arthrography to determine whether oblique head positions were helpful in diagnosing internal derangement of the temporomandibular joint (TMJ). After injection of contrast material, inclined transcranial lateral spot films were obtained with the patient's head in upward oblique, downward oblique, and neutral positions. The spot films were analyzed for internal derangement by assessing the size of the mass effect on the arthrogram. Twelve of the 13 arthrograms showed evidence of internal derangement of the TMJ. However, the apparent size of the mass effect varied in different head positions. Each of the three views failed to demonstrate the mass effect in at least one instance (eight different patients). No head position was better than another in demonstrating the mass effect. Thus, oblique head positions are useful adjuncts for diagnosing internal derangement of the TMJ.

Arthrography↗
PubMed1986

Foraminal spurs: a normal variant in the lumbar spine.

A normal variant, the foraminal spur, is described in five patients. It was seen on computed tomographic studies as a bony process extending from either the pars or the pedicle into the neuroforamen dorsal to the nerve root. In four of the cases it was seen bilaterally. None of the patients had any symptoms related to these spurs. No associated disease of the neuroforamen or facet was present. These spurs most likely represent ossification of the ligamentum flavum at its point of insertion and should not be mistaken for osteophytes, free disk fragments that have calcified, or fracture fragments. Sagittal reformations are helpful in visualizing the extent of the foraminal spurs.

Humans↗
PubMed1986

Magnetic resonance imaging of internal derangement of the temporomandibular joint.

MRI is currently capable of diagnosing anterior derangements of the temporomandibular joint. Although large prospective studies comparing MRI with conventional modalities have not yet been done, early evidence suggests that findings seen on high-resolution surface coil MR images correlate very well with CT, arthrographic, and surgical findings. Much additional work will need to be performed before MRI of the temporomandibular joint becomes a standard diagnostic tool. However, we believe strongly that it will begin to replace arthrography and CT for diagnosing internal derangements within the next few years.

Arthrography↗
PubMed1986

Magnetic resonance imaging of osteonecrosis.

Because the available preliminary data strongly indicate that MRI is accurate in diagnosing osteonecrosis, MRI of the hips is recommended in patients suspected of having osteonecrosis, especially if other diagnostic studies are equivocal. MRI also may be useful in following patients who have strong risk factors for osteonecrosis, such as corticosteroid therapy, femoral neck fracture, traumatic femoral head dislocation (Fig. 13), slipped capital femoral epiphysis (Fig. 14), and congenital hip dislocation. In diseases such as systemic lupus erythematosus, both hips eventually may become involved in 50 to 80 per cent of cases. Therefore, the unaffected hip of patients with systemic lupus erythematosus and unilateral nontraumatic osteonecrosis of the hip should be monitored regularly with MRI. The hope is that early diagnosis and treatment of femoral head osteonecrosis will prevent the relentless progression to subchondral collapse and disabling arthropathy. MRI also may be useful in staging patients known to have osteonecrosis. The ability of MRI to image directly in multiple planes facilitates the determination of the volume and location of infarcted segments of bone. This information is important in planning any of the surgical procedures used relatively early in the disease, such as core decompression, rotational osteotomy, or bone graft. Moreover, MRI may prove helpful in evaluating the effectiveness of any therapeutic intervention.

Adrenal Cortex Hormones↗
PubMed1986

Magnetic resonance imaging of musculoskeletal neoplasms.

MRI has been shown to be very useful in the work-up of musculoskeletal neoplasms. The lack of ionizing radiation, the superb contrast resolution, and the ability to directly scan the sagittal and coronal planes make MRI a very attractive imaging mode for treatment planning. With spin-echo MRI, maximum contrast between tumor and fatty tissues generally occurs with short TR and TE times (T1-weighted images). Likewise, maximum contrast between tumor and muscle, tendon, or ligaments occurs with long values of TR and TE (T2-weighted images). Early experience suggests that the already exceptional contrast resolution seen with MRI can be improved even more with the administration of intravenous contrast agents. Just as with CT, fatty tumors can usually be easily distinguished from other tissue types with MRI by means of their differential intensity behavior at different pulse sequences. Fluid-filled tumors, such as unicameral bone cysts or aneurysmal bone cysts may be suspected in the same manner, especially if a fluid-fluid level is seen within the lesion. Otherwise, MRI has not been useful so far in noninvasively determining the histologic type of tumors. Our experience and that of others suggests that MRI is equal or superior to CT in the work-up of musculoskeletal neoplasms. This is especially striking when it is remembered that one is comparing an immature MRI technology with a mature CT technology. Although CT presently has a central role in the staging of musculoskeletal tumors, MRI will shortly supplant it in many cases.

Adult↗
PubMed1985

Theoretical considerations for optimizing intensity differences between primary musculoskeletal tumors and normal tissue with spin-echo magnetic resonance imaging.

In the radiographic assessment of primary musculoskeletal tumors, it is important for therapy planning to accurately define the extent of a tumor. Using a double spin-echo pulse sequence, the T1 and T2 relaxation times and relative hydrogen densities of several neoplastic tissues and of several normal tissues in four patients were measured. Neoplasms measured included one fibrosarcoma, two osteosarcomas, and one giant cell tumor. Normal tissues measured included normal muscle, fat, and bone marrow. Using a mathematical model of the double spin-echo pulse sequence, the intensity difference between each tumor and each normal tissue for multiple values of TR and TE was calculated. These calculated intensity differences were then used to plot isodifference contour curves for each tissue pair. These plots enabled us to pick combinations of TR and TE that optimized the signal difference between tumor and normal tissue. When comparing tumor with predominantly fatty tissue such as marrow or subcutaneous fat, optimal signal difference in our imager occurred at a TR of 600 to 800 msec and a very short TE. When comparing tumor with muscle, optimal signal difference occurred with very long TR times, and TE times ranging from 30 to 90 msec. These preliminary results suggest that an optimal scanning protocol for primary musculoskeletal tumors should contain at least two different pulse sequences with widely separated TR values (500 and 2000 msec in our instrument), and short to intermediate values of TE (28 and 56 msec in our instrument). It is believed that analysis of isodifference contour plots is a useful method for optimizing intensity differences between any two tissue types.

Bone Neoplasms↗
PubMed1985

Bony spinal canal changes that differentiate conjoined nerve roots from herniated nucleus pulposus.

CT examinations of the lumbar spine in 12 consecutive patients with conjoined nerve roots were reviewed. Asymmetry of the bony spinal canal, seen as slight dilatation of the ipsilateral lateral recess, was present in all cases. This finding, which is not typically associated with extruded free intervertebral disk fragments, should serve to distinguish these two entities.

Diagnosis, Differential↗
PubMed1985

Chronic osteomyelitis examined by CT.

CT examination of 25 patients who had acute exacerbations of chronic osteomyelitis allowed for the correct identification of single or multiple sequestra in 14 surgical patients. Plain radiographs were equivocal for sequestra in seven of these patients, because the sequestra were too small or because diffuse bony sclerosis was present. CT also demonstrated a foreign body and five soft tissue abscesses not suspected on the basis of plain radiographs. CT studies, which helped guide the operative approach, were also useful in treating those patients whose plain radiographs were positive for sequestra. We review the potential role of CT in evaluating patients with chronic osteomyelitis.

Adolescent↗
PubMed1985

Percutaneous lumbar diskectomy using a new aspiration probe: porcine and cadaver model.

A method of percutaneous aspiration of the nucleus pulposus of lumbar disks is described as performed in four pigs and three cadavers. Through a lateral oblique percutaneous approach, 80-100% of the nucleus pulposus was removed in each of the pigs; approximately 30% of the cadaver disk was removed. A unique aspiration probe and the introducing set as well as the technique are described. The implications for clinical use in patients are discussed. We believe this technique may be an alternative to both surgical diskectomies and chymopapain injection in the treatment of herniated disk disease of the lumbar spine.

Adult↗