CT features of recurrent lumbar disc herniation.

The CT findings of 29 patients with recurrent lumbar disc herniation, confirmed at reoperation, were analyzed. The shape of the recurrent herniation varied from a shallow bulge to round or triangular mass. Every lesion presented density numbers compatible with disc material. An enhancement study was made in six cases, and the lesions remained non-enhanced. Density measurement on CT proved reliable in the differential diagnosis between recurrent disc herniation and postoperative scar.

Comparison of the radiation doses in lumbar CT and myelography.

The radiation doses of the vertebral bodies and ovaries in lumbar CT and myelography were compared using a phantom. The CT examinations were performed with two different scanners using four different programs. At CT the radiation maximum doses of the vertebral bodies were higher than at myelography but the ovarian doses were lower. The radiation exposure does not prevent the use of CT instead of myelography, but the area of examination and the number of pictures should be limited to the minimum based on the clinical enquiry.

The helical three-dimensional CT in the diagnosis of torticollis with occipitocondylar hypoplasia.

Congenital anomalies of the atlanto-occipital and atlantoaxial joints are rare. Those most commonly reported are atlantoaxial instability, basilar impression, anomalies of the odontoid process, laxity of the transverse atlantal ligament and atlanto-occipital fusion. Occipital condylar hypoplasia is infrequent and difficult to recognise. We recently diagnosed it using helical 3D CT in association with torticollis in two patients. The first patient had a several year history of torticollis. The second patient had acute cervical lymphadenitis associated with post-operative torticollis. 3D CT distinctly revealed atlantoaxial subluxation with hypoplasia of the occipital condyles in both cases.

Late CT-findings in non-surgically treated lumbar disc herniations.

Eighteen patients with non-surgically treated lumbar disc herniation underwent follow-up CT examination at an average of 5.2 years (range 4.3-6.1 years) after their initial examination. In 12 of the patients disc herniation had resolved, although only five of these patients had complete relief of symptoms. Although disc herniation has a tendency to heal spontaneously, there is poor correlation between the morphological changes and the relief of pain.

Low-cost digital teleradiology.

A teleradiology link based on standard personal computers and a flat-bed CCD scanner was tested. A 64 kbit/s dial-up digital ISDN telephone line was used for transmission. A total of 254 films (174 uncompressed, 80 compressed) were sent. Ninety-six per cent of the uncompressed images and 98% of the compressed images were considered technically acceptable. The total diagnostic agreement between the acceptable transmitted images and the original films was 98%. Image quality was sufficient for diagnosis in CT and conventional chest and bone radiographs. However, a 256-step gray scale of the scanner was not sufficient for demanding situations, such as overexposed images with a high contrast gradient. The average speed of transmission was 60 kbit/s, which was considered adequate. The tested system suggests that a teleradiology link based on standard personal computers and programs works in situations where instant consultation is needed. However, the image digitization time with the prototype system was quite long, and a better user interface is under development.

Association of atherosclerosis with low back pain and the degree of disc degeneration.

STUDY DESIGN: This was a cross-sectional observational study in which the abdominal aorta was evaluated for atheromatous lesions visible in computed tomographic scans in patients with and without low back pain. OBJECTIVES: To evaluate whether patients with low back pain have more atherosclerosis in the abdominal aorta than patients without low back pain and whether the severity of atherosclerosis in the abdominal aorta correlates with the grade of disc damage. SUMMARY OF BACKGROUND DATA: There are studies in which results indicate that insufficient blood supply may be a significant causative factor in disc degeneration. There are also studies in which smoking, one of the risk factors for arterial disease, has been correlated with low back pain. Calf pain has also been shown to correlate with low back pain. Results in a long-term follow-up study have further indicated an association between disc diseases and fatal ischemic heart disease. However, there seems to be only one postmortem study in which results show an association between atherosclerosis in the arteries of the lumbar area and disc diseases. METHODS: Computed tomographic images of 29 patients with low back pain, who had been evaluated with computed tomographic discography for diagnostic purposes, were evaluated for the quantity of atherosclerotic calcifications visible on computed tomographic scans of the abdominal aorta. A similar evaluation was performed in an age- and sex-matched control group of 52 patients without low back pain selected from among the patients referred for abdominal computed tomography. RESULTS: Sixteen (55%) of the 29 patients with low back pain had atherosclerotic calcifications visible on computed tomographic scans, whereas 11 (21%) of the 52 age-matched patients without low back pain were found to have aortic calcifications. Eleven (48%) patients with low back pain who were 50 years of age or less (n = 23) had aortic calcifications, whereas only 3 (8%) of the 36 control patients aged less than 50 years had aortic calcifications. There was no correlation between the amount of calcifications and the degree of disc degeneration assessed by computed tomographic discography. CONCLUSIONS: A significant association is indicated between atheromatous lesions in the abdominal aorta and low back pain.

Preoperative virtual endoscopy and three-dimensional imaging of the surface landmarks of the internal carotid arteries in trans-sphenoidal pituitary surgery.

In trans-sphenoidal pituitary adenoma surgery the sella turcica is opened between the internal carotid arteries. Three-dimensional image processing methods were applied in this study to avoid the risk of damaging the arteries during the opening of the anterior wall of the sella. By using graphical software it was possible to combine the anatomies of the carotid arteries and the sellar wall into one non-perspective three-dimensional image. With a perspective image (virtual endoscopy), the sphenoid sinus landmarks were presented as if looking through a nasoendoscope. This also facilitated preoperative planning but the non-perspective images, with the carotid arteries marked, were found to be the most useful and suitable for clinical routine. The pituitary tumor itself and its relations with the adjacent structures were best evaluated from magnetic resonance imaging scans but, for the opening of the sellar wall and in the three-dimensional orientation with endoscopy, three-dimensional computerized tomography imaging with the carotid arteries marked was found to be helpful.

Initial experience with a wireless personal digital assistant as a teleradiology terminal for reporting emergency computerized tomography scans.

A new type of terminal device, a wireless personal digital assistant (PDA) based on a GSM digital cellular phone, was used to transmit computerized tomography scans of 21 patients to a neuroradiologist. All transmitted images were suitable for a preliminary consultation and in one case a final report could be made. In 18 cases the findings were compatible with the reference film reading performed later and in three cases there were minor differences of no clinical importance. Transmission of a single image lasted 1 min 30 s and the transmission of a complete brain scan (14 images) took on average 21 min. The total process of transmission and interpretation of a brain examination series took on average 40 min. In this pilot study the neuroradiologist gained essential information in 24% of the cases and beneficial information in 62%. The neuroradiologist considered that the image consultation saved a hospital visit in 15 cases (71%). Although PDA technology is at an early stage of development and has numerous limitations, it is likely that future technical improvements will allow easier clinical consultations for neurosurgeons and neurologists.

Digital wireless radiology consultations with a portable computer.

A wireless system for radiological subspecialist consultation based on a portable personal computer and a GSM cellular phone was tested. A link with secure access to the hospital image network was built. A total of 68 emergency computerized tomography (CT) examinations were transmitted. Transmission time via GSM for a single CT image was 1 min and for a complete head scan was 18 min. The transmitted images were acceptable for final diagnosis in 72% of the cases, the rest being acceptable for preliminary diagnosis. The diagnosis from the transmitted images did not change after a later review of the original images in 97% of cases. The wireless link saved a hospital visit by the senior radiologist in 24% of cases. The results show that a remote consultation link can be built with readily available technology and that the technique is useful in radiological subspecialist consultations for CT images.

Nasopharyngeal dimensions in magnetic resonance imaging and the risk of acute otitis media.

BACKGROUND: We have previously found by lateral cephalometry an association between nasopharyngeal anatomy and the risk of acute otitis media (AOM). We evaluate here the association of nasopharyngeal dimensions in magnetic resonance imaging (MRI) with the occurrence of AOM in otherwise healthy children. METHODS: Sixty-one healthy children (mean age 5.7 years, range 3.9-6.9) were recruited from child care centres. The parents filled in a questionnaire on the child's history of ear infections and adenoidectomy. MRI was performed with a 4 mm slice thickness during an upper respiratory infection. Five dimensions and two angles expressing the structure of the bony nasopharynx were measured in sagittal images. RESULTS: The dimension from the caudal edge of the septum to the midpoint of the sella, reflecting the height of the nasopharynx, was on average 2.2 mm smaller in the children who had had AOM attacks during the last 12 months than those without attacks (95% confidence interval (CI) 0.9 to 3.4, p=0.001) and the nasal base angle was on average 2.1 degrees smaller (95% CI 0.7 to 3.5, p=0.004). These differences remained significant after adjustment for age, sex and previous adenoidectomy in the logistic modelling. A history of adenoidectomy did not have any effect on the dimensions. CONCLUSIONS: The nasopharynx was smaller in the children with AOM attacks during the last year. The value of this finding for predicting susceptibility to recurrent AOM and directing preventive procedures should be evaluated.

Chronic encapsulated intracerebral haematomas.

We present four patients with uncommon encapsulated intracerebral haematomas (ICH). Because of ring enhancement, three were incorrectly diagnosed as gliomas and operated upon. In one case the diagnosis of chronic ICH was made on MRI. MRI can be used to demonstrate that a lesion is only a haematoma and is valuable in follow-up and in differentiating these haematomas from neoplasms. Angiography may reveal a vascular malformation which may be the reason for repeated bleeding, which may lead to encapsulation. The mechanism, however, remains unclear in most cases.

Wooden foreign bodies in CT. Case reports and experimental studies.

CT findings in 2 patients with a wooden foreign body in the orbital region soft tissue, and a series of CT measurements of wooden elements are presented. The wooden foreign bodies presented low HU numbers in CT and were initially interpreted as a gas collection. Different species of trees presented a large spectrum of densities, varying from the -550 HU of pine up to the +289 HU of ebony. The density of a spruce plank increased along with water-logging from -470 HU to -86 HU in 4 weeks, and peak enhancement up to 106 HU was found in the layer closest to the surface. It was concluded that a wooden foreign body in soft tissues may present CT patterns simulating materials as different as a gas bubble or a bone fragment.

Superficial siderosis in the central nervous system.

We describe a rare entity, superficial siderosis of the central nervous system, due to multiple small episodes of subarachnoid haemorrhage from any source. Nonspecific neurological findings are associated with deposition of iron-containing pigments in the leptomeninges and superficial layers of the cortex. T2-weighted magnetic resonance imaging demonstrates characteristic low signal in the meninges.

Thin-section CT in the examination of cervical disc herniation. A prospective study with 1-mm axial and helical images.

PURPOSE: The aim of the investigation was to determine whether thin-section high-resolution CT imaging could replace MR imaging and/or myelography in preoperative evaluation of radiculopathy and/or myelopathy. MATERIAL AND METHODS: A total of 120 patients, referred for cervical myelography (n=107) or MR imaging (n=13), were further examined with 1-mm non-contrast CT of the suspected disc space, including at least the next cephalic and caudal interspaces. Thirty-seven patients underwent Cloward's operation, at which 32 were found to have disc herniation. RESULTS: The sensitivities of CT (n=37), myelography (n=29) and MR imaging (n=8) were 66%, 84%, and 86%, respectively. The corresponding figures for false-positives were 8%, 10%, and 13%. Artefacts caused by wide shoulders in the 1-mm CT images were estimated to have contributed to a false-negative finding in 8 cases. The remaining 3 false-negatives were retrospectively considered evaluation errors. The true-positive CT findings usually presented with a local disc bulge measuring over 80 HU in density. Local ligamentous hypertrophy presented an indistinguishable finding in 3 cases, yielding false-positive CT findings. CONCLUSION: Conventional thin-section CT is considered a usable alternative for the evaluation of suspected cervical disc herniations in selected patients. Stocky patients with wide shoulders and a short neck are not suitable candidates, even when new generation equipment is available.

Computed tomography after lumbar disc surgery.

Computed tomography (CT) findings following lumbar disc surgery were analyzed in a series of 53 patients one week after surgery and in another series of 43 patients 6 months to 20 years (average 4.3 years) after surgery. In addition to changes caused by the surgical exposition (laminotomy or laminectomy, gas bubbles) a mass lesion was found on the posterior aspect of the disc in all cases. Hypodensity of the disc interspace as well as vacuolization were found in several cases. These changes were less in the patients examined late after surgery but the CT findings were never completely normal. Findings characteristic of recurrent prolapse included disc-like attenuation values within the mass and non-enhancement with contrast medium. Hypodensity of the disc interspace is associated with discitis but as a non-specific finding it is insufficient in itself for diagnosis of discitis.