Computed tomography of stress fracture

An athletic young female developed gradual onset of pain in the right leg. Plain radiographs demonstrated solid periosteal reaction in the tibia compatible with stress fracture. She stopped sport activites but her pain continued. Follow-up radiographs of the tibia revealed changes suspicious for osteoid osteoma. Computed tomography (CT) scan demonstrated periosteal reaction, but in addition, lucent fracture lines in the tibial cortex were evident. CT obviated the need for more invasive diagnostic procedures in this patient. In selected cases CT may be useful to confirm the diagnosis of stress fracture when plain radiographic or routine tomographic studies are not diagnostic.     

Quantitative and qualitative assessment of closed fracture healing using computed tomography and conventional radiography

RATIONALE AND OBJECTIVES: Development of new agents to induce fracture healing requires more sensitive methods to detect early changes in fracture repair. The aims of this study were to determine quantitative and qualitative features of fracture healing using volumetric computed tomography (CT) and to compare them with conventional radiography during the weeks following uncomplicated fractures of the appendicular skeleton. MATERIALS AND METHODS: 39 otherwise healthy men and women with acute, closed fractures of the distal radius, tibial and/or fibular malleoli, or tibial shaft, were enrolled and underwent CT and X-ray imaging at 1, 2, 4, 8, 12, and 16 (tibial shaft only) weeks post fracture. Qualitative assessment included fracture line/margins, fracture gap, external callus appearance, callus-to-cortex ratio, bridging, and radiologic union. Quantitative assessment of CT density changes (Hounsfield units [HU]) in the fracture gap was performed in a subset of 8 fracture patients using MEDx multimodality image analysis software (Sterling,VA). The analysis was performed by drawing free form regions of interest (ROI) covering the fracture gap on baseline (week 1) images and by automated registration of the follow-up images to the baseline co-ordinate system. RESULTS: The mean time to achieve radiologic union on CT was slightly shorter than on X-rays for radial and tibial shaft fractures (7.3 vs. 8.0 weeks, P = .1). Blurring of the fracture margins and reactive sclerosis were the earliest signs of healing in both modalities. External callus formation was evident in 11 cases and was detected earlier with CT technique. Overall, CT images allowed for more complete and detailed visualization of healing compared with conventional X-rays, which were limited by cast and fixation hardware superimposition, especially in subjects with malleolar and distal radial fractures. Quantitative evaluation showed good intraobserver and interobserver reproducibility and a statistically significant correlation to qualitative changes. CONCLUSION: Our methods of fracture healing assessment are reliable tools that are able to detect early changes in normal bone healing and may serve as useful additions to subjective image analysis in monitoring fracture healing in clinical trials. CT shows some advantages over conventional X-rays in evaluation of early fracture healing.     

The reliability of plain radiography in experimental fracture healing

Objective. To investigate the reliability of radiographs in the evaluation of healing of closed fractures. Design. A closed midshaft tibial fracture was created in 40 goats and stabilized with an external fixator. The animals were assigned to four groups: no injection, injection of 1 mg osteogenic protein-1 (OP-1), 1 mg OP-1 with collagenous carrier, or carrier alone. Radiographs were performed weekly until the animals were killed after 2 and 4 weeks. Healing was evaluated using radiographs, biomechanical testing, and histological examination. All radiographs were examined by two independent observers. Interobserver agreement was calculated and radiographic scores were compared with mechanical and histological scores using regression analysis. Results. Regression analysis showed poor correlation between radiogra-phic scores and biomechanical and histological data. Correlation coefficients varied between 0.39 and 0.63. Good agreement between the obser-vers was seen in only three parameters: visibility of the fracture line, weightbearing ability, and a combined healing parameter. Conclusion. Plain radiography provides poor parameters for monitoring the fracture healing process. Received: 2 August 2000 Revision requested: 3 October 2000 Revision received: 31 October 2000 Accepted: 20 November 2000     

Computed tomography and intracranial aspergillosis

Summary A case of aspergillosis of the central nervous system with multiple granulomas examined by computed tomography is reported. The findings are those of chronic mass lesions with and without calcium deposits. An associated cystic configuration probably is not specific for aspergillomas.     

Computed tomography and three-dimensional reconstruction in the evaluation of occipital condyle fracture

Two cases of a rare Anderson type III occipital condyle fracture are presented. In any patient sustaining craniovertebral injury an occipital condyle fracture may be missed because plain films can be unremarkable. It is important to include computed tomography or coronal hypocycloidal tomography for all suspect cases of craniovertebral junction injury. Although three-dimensional reconstruction did not alter therapy for this injury, spatial localization of the fracture fragment was enhanced by this method. Serious neurological deficits are possible if this unusual injury is not treated.     

Computed tomography of intrathecal thorotrast

Summary Thorotrast is distributed in the cerebral subarachnoid space in a distinctive manner. Computed tomography is an excellent method for demonstrating this distribution.     

The normal cervical spine and its variations on plain radiography and computed tomography

To detect abnormalities of the injured bony cervical spine, it is necessary to have a thorough knowledge of the normal cervical spine’s anatomy and its variations. It is the purpose of this article to emphasize the visual characteristics of the normal appearances in order to assist in the determination of whether the examination is normal or abnormal. Because of these visual characteristics, it is at times possible to be certain that the examination is normal solely on basis of the plain radiographs. On other occasions, because the plain radiographic appearance of normal and abnormal may overlap, further evaluation with computed tomography is necessary. Rarely, even with computed tomography, the appearance of normal, subacute injury, and acute injury may not be distinguishable.     

Computed tomography in ophthalmology

Summary The practical value of density measurements with computed tomography of orbital lesions is demonstrated.     

Computed tomography in Alexander's disease

Summary Two cases of biopsy-proven Alexander's disease are described with computed tomographic changes which, in our experience and on survey of the literature, have not occurred in any other condition. Such changes in a child with a progressive condition consistent with Alexander's disease, strongly support the diagnosis.     

Computed tomography in Alexander's disease

Summary A case of biopsy proven Alexander's disease is described with extensive low density lesions in both frontal lobes, which in our experience, and on survey of the literature have not been described previously.     

Postoperative evaluation of femoral tunnel position in ACL reconstruction: plain radiography versus computed tomography

Inaccurate femoral tunnel placement has been identified as one of the most frequent errors in failed anterior cruciate ligament reconstructions. Most surgeons evaluate the femoral tunnel position on plain radiographs but in a lot of cases it is difficult to detect the femoral tunnel. The goal of this study was to compare plain digital radiographs and multiplanar computed tomography (CT) scans for the evaluation of femoral tunnel position. We examined 50 patients 24–60 months postoperatively, following an arthroscopically-assisted anterior cruciate ligament reconstruction with central third bone–patellar tendon–bone graft. Endobutton fixation was used on the femoral side and titanium interference screws on the tibial side. Standard antero-posterior and lateral X-rays and a CT scan were obtained from each patient. Sagittal and frontal reconstructions of the CT scan were used for the evaluation. We measured the height of the center of the tunnel in the notch in the frontal plane, and the position of the tunnel along Blumensaats line (BL) in the lateral plane. Measurements are reported as percentages of total notch height and of the length of BL. On plain X-rays the tunnel was invisible in 46 cases in the anterior–posterior plane and in eight cases on the lateral plane. The average position in the frontal plane was 89.8%, and in the lateral plane 38.6%. In the CT scans, measurements were able to be done in 48 patients. The frontal-plane position averaged 90.5% and the lateral-plane position 34.1%. Pearsons correlation coefficient for the values in the lateral plane for CT and X-rays was low at 0.22, with p>0.05. In our group of 50 patients we were able to detect the femoral tunnel on both plains of standard X-rays in only four patients, whereas it was possible to take accurate measurements in 48 patients on reconstructed CT scans. We advocate the use of CT technology for the evaluation of femoral position whenever precise measurements are needed.     

Computed tomography of intramuscular myxoma

Computed tomography (CT) was performed in seven patients with intramuscular myxoma. All lesions were well demarcated, of homogeneous appearance and attenuation values ranging from 10 to 60 (HU). The tumor size, as estimated at CT, correlated well with the size of the surgical specimen, which is in contrast to the findings in some high grade malignant sarcomas.     

Computed tomography in acute haemorrhagic leukoencephalitis

Summary Three patients with biopsy-proven acute haemorrhagic leukoencephalitis are described. All presented with an abrupt onset of focal neurological signs, pyrexia and leukocytosis. In two cases there was disturbance of consciousness. Computed tomography in each case revealed low density virtually confined to the white matter of the cerebral hemisphere; in one case there was central enhancement within the low density. The combined clinical and CT signs should strongly suggest the diagnosis.     

Computed tomography in the diagnosis and differential diagnosis of glioblastomas

Summary The CT patterns of 295 glioblastomas examined with pre- and postcontrast scans using an EMI scanner mark I (Matrix 160/160) have been reviewed and compared with the CT appearances of other brain tumors, metastases and abscesses. There is a great variety of CT patterns with glioblastomas. However, a garland-shaped CT appearance, representing a subgroup of ring-shaped lesions, seems to be most typical for glioblastomas since it was observed in 19% of ring-shaped glioblastomas but in only one out of 172 metastases and in no case of an astrocytoma grade II or an abscess in our series. The initial CT diagnosis, based on the CT finding, the patient's history and the clinical data, was correct in 69.8% of the glioblastomas, 41 recurrent glioblastomas included. In 12% of the cases the presence of a glioblastoma was within differential diagnosis. These results lead to the conclusion that in many cases additional diagnostic methods, such as serial scintigraphy and/or cerebral angiography, are required for a reliable differential diagnosis.     

Computed tomography of cavernous sinus diseases

Summary We retrospectively analyzed CT scans of 21 cavernous sinus lesions in an attempt to discover CT findings helpful to the differential diagnosis. With the integration of various CT observations it was possible to categorize the lesions into inflammatory, vascular, benign neoplastic and malignant metastatic lesions with few exceptions. Four of 5 cases of septic cavernous sinus thrombophlebitis revealed unilateral or bilateral multiple irregular filling defects in the enhancing cavernous sinus with or without orbital inflammatory change. Four of 5 cases of carotid-cavernous fistula demonstrated unilateral or bilateral diffuse bulging and homogeneous enhancement of the cavernous sinus with obliteration of normal low densities of cranial nerves and gasserian ganglion. Dilatation and tortuosity of superior ophthalmic vein were also associated. Four of 5 cases of benign neoplastic lesion showed well-circumscribed enhancing masses confined to the cavernous sinus with pressure erosion or hyperostosis of adjacent bone. Five of 6 cases of malignant metastatic lesion showed changes suggesting malignancy such as destruction of adjacent bone or associated manifestations of intracranial spread. As compared with the axial scan, coronal scans proved to be more sensitive in detection of subtle cavernous sinus expansion, and superior in evaluation of intracavernous neural structures, relationships with the pituitary gland and changes in the skull base. Axial scans, however, were superior in detection of associated orbital and intracranial abnormalities. Scans in both projections are needed in the evaluation of most cavernous sinus diseases.     

Computed tomography in management of medulloblastomas

Summary The neuroradiological studies of 116 patients with histologically verified medulloblastomas, which had been examined with plain and contrastenhanced computed tomography (CT), were reviewed. The typical CT appearances of a well-defined, hyperdense enhancing mass in the vermis, with surrounding oedema, occurred in 60% of this series. Atypical features include calcification (17%), cystic or necrotic regions (47%) or poorly defined margins and lack of enhancement (7%). Such features in a vermis mass presenting in the first decade, especially in a boy, should not be considered against the diagnosis of medulloblastoma, but may be misleading when the tumour predominantly involves a cerebellar hemisphere.     

Computed tomography in the diagnosis of cerebral abscess

Summary Computed tomography (CT) was performed 64 times on 22 patients with cerebral abscesses, using the 160x160 matrix EMI scanner. The diagnosis was based upon the demonstration of a localized low-attenuation area appearing, after the administration of contrast medium, as a high-attenuation annular rim ascribed to displaced and/or newly formed vessels, the so-called abscess membrane. CT is compared with the conventional diagnostic methods of neuroradiology. The differential diagnostic accuracy of CT is clearly superior to that of previous methods, including angiography, which, until now, we have considered the most accurate method.     

Computed tomography and aging: results in a normal elderly population

Summary CT studies on 212 normal elderly individuals were analyzed for ventricular enlargement and cortical atrophy. Results show a positive correlation between ventricular enlargement and age with greater degrees of ventricular enlargement and cortical atrophy in men as compared to women. While some degree of atrophy is common in normal elderly individuals it is mild, minimal, or noexistent in 86%.Supported in part by NIMH grant 2RO1 MHAG27281     

Computed tomography in spinal tuberculosis

Exhaustive ciinicoradiologic and computed tomographic (CT) analysis of 114 cases of spinal tuberculosis seen between January 1983 and January 1989 is presented. The mechanisms of the spinal involvement are reviewed. CT helped to diagnose cases of spinal tuberculosis in their initial stages. Inaccessible fixed areas of spine were seen with ease on axial sections of CT. The extent and anatomic depiction of soft-tissue involvement as depicted on CT helps surgeons choose the appropriate surgical approach, which may affect future spinal stability.