Magnetic Resonance Imaging of an Epidural Spinal Arachnoid Cyst

The myelography, CT and MR imaging findings in a patient with an epidural spinal arachnoid cyst are discussed. MR imaging excellently demonstrated cyst size, cyst location and cord compression, and should be the method of choice in these cases.

Comparison of 12-Bit and 8-Bit Gray Scale Resolution in Mr Imaging of the CNS

A reduction in gray scale resolution of digital images from 12 to 8 bits per pixel usually means halving the storage space needed for the images. Theoretically, important diagnostic information may be lost in the process. We compared the sensitivity and specificity achieved by 4 radiologists in reading laser-printed films of original 12-bit MR images and cathode ray tube displays of the same images which had been compressed to 8 bits per pixel using a specially developed computer program. Receiver operating characteristic (ROC) curves showed no significant differences between film reading and screen reading. A paired 2-tailed t-test, applied on the data for actually positive cases, showed that the combined, average performance of the reviewers was significantly better at screen reading than at film reading. No such differences were found for actually negative cases. Some individual differences were found, but it is concluded that gray scale resolution of MR images may be reduced from 12 to 8 bits per pixel without any significant reduction in diagnostic information.

Craniopharyngiomas — The Utility of Contrast Medium Enhancement for MR Imaging at 1.5 T

To evaluate the efficacy of i.v. contrast medium administration in MR imaging at 1.5 T in patients with craniopharyngiomas, MR studies of 10 men and 6 women with pathologically proven craniopharyngiomas were made. The MR images were obtained as 3- to 5-mm-thick coronal (n = 13) or axial (n = 3) T1-weighted images (T1WI) prior to and following i.v. Gd-DTPA administration. Proton density- (PD) and T2-weighted images (T2WI) were also obtained. Conspicuity of tumor margins, cystic versus solid components, size, location and effect upon adjacent structures were separately characterized in all imaging sequences. In 6 patients contrast medium-enhanced T1WI, PD and T2WI demonstrated cystic tumor components not seen on unenhanced T1WI. There were significant differences (p < 0.004) on 2-tailed Student's t-test comparing tumor conspicuity on contrast medium-enhanced T1WI with unenhanced T1WI, PD and T2WI. Optimal tumor delineation on MR imaging of patients with craniopharyngiomas justifies the use of i.v. contrast medium.

Coronal MR Imaging of the Normal 3rd 4th and 5th Lumbar and 1st Sacral Nerve Roots

Seven healthy volunteers underwent coronal MR imaging at 1.5 tesla of the normal 3rd, 4th, and 5th lumbar, and 1st sacral nerve roots. Coronal slices, 3-mm-thick with a 0.3-mm gap between the slices were obtained (TR/TE 600/22) through the lumbar spinal canal. All the nerve roots were visible on at least one image. One can routinely expect to demonstrate the 3rd, 4th, and 5th lumbar, and 1st sacral nerve roots on T1-weighted, 3-mm-thick coronal MR scans. We found no correlation between the degree of lumbar lordosis and the lengths of the visible nerve roots. Five patients with one of the following spinal problems: anomaly, tumor, disk herniation, and failed back surgery syndrome were examined according to our protocol. In all these cases coronal MR imaging gave the correct diagnosis.

MR Imaging of Pituitary Region Lesions with Gadodiamide Injection

Twelve patients with known or suspected pituitary lesions underwent MR imaging with gadodiamide injection at a dose of 0.1 (n = 5) or 0.3 (n = 7) mM/kg. Six of the patients were also studied with 0.1 mM/kg gadopentetate dimeglumine. Consistent with previous reports gadodiamide injection was found to be a safe and effective contrast medium for MR imaging of the pituitary region. No additional diagnostic information was obtained using 0.3 mM/kg gadodiamide injection compared to 0.1 mM/kg gadopentetate dimeglumine in the same patients. The high dose (0.3 mM/kg) gadodiamide injection in 7 patients did not shorten the T2 value sufficiently to overwhelm the T1 shortening and leave pathologic lesions hypointense compared to precontrast studies. With the comparable relaxivities of gadodiamide injection and gadopentetate dimeglumine, similarities in results have to be expected when using these media for MR image enhancement.

Mr Imaging of Pituitary Macroadenomas before and after Transsphenoidal Surgery

MR findings before and after transsphenoidal surgery were evaluated in 6 cases. T1-weighted (TR/TE 600/20) sagittal and coronal images with 2 or 4 acquisitions were obtained, using 3-mm slice thickness and 0.3-mm interslice gaps. Of 18 MR examinations, 13 included coronal i.v. contrast medium enhanced images. Image quality, sinus cavernosus invasion, identification of normal pituitary tissue and tumor size were examined. All MR studies clearly demonstrated the macroadenomas whether 2 or 4 acquisitions were used, and whether i.v. contrast medium was administered or not. Surgically confirmed sinus cavernosus infiltration was seen in 4 patients. The pituitary stalk was identified separate from the tumor in 2 patients, and the gland in one. There was reduction in tumor size over time, indicating that final radiologic assessment after transsphenoidal surgery is best performed 4 to 6 months postoperatively. It should not be necessary to routinely include i.v. contrast medium injection in the postoperative evaluation of macroadenomas.

Carotid-Cavernous Fistula Treated with Detachable Balloon during Bilateral Transcranial Doppler Monitoring of Middle Cerebral Arteries

A traumatic carotid-cavernous fistula was closed with a silicone detachable balloon. Prior to the closure of the fistula, clinical and transcranial Doppler testing was performed in order to evaluate the consequences of a possible occlusion of the carotid artery. A newly developed Doppler technique with bilateral simultaneous velocity recordings of the middle cerebral arteries was useful during the procedure. The detachable balloon was effective in closing the fistula, but collapse of the balloon and the development of an extradural aneurysm was found at control examinations.

Craniopharyngioma Identification by CT and MR Imaging at 1.5 T

To compare the detectability of craniopharyngiomas by CT and MR imaging, preoperative CT and MR studies obtained within 16 days of each other were evaluated retrospectively in 9 patients. MR imaging demonstrated cystic and solid tumor components in all 9 tumors, and enhancement in the 7 tumors that were studied after contrast medium injection. MR imaging demonstrated a signal void consistent with calcification in 4 patients. Combining unenhanced and contrast medium-enhanced studies, CT also identified all the tumors. CT demonstrated cysts in 7 lesions, calcification in 7 and enhancement in 6 of the 7 lesions that received i.v. contrast medium. Calcification was better seen by CT than MR imaging, while MR imaging identified cystic tumor components not seen on CT. The contrast medium enhancement pattern was the same with the 2 modalities. MR imaging of the sellar region, including at least one contrast medium-enhanced sequence, should be sufficient in most instances to establish a preoperative diagnosis of craniopharyngioma.

Delayed diffusion-weighted MR abnormality in a patient with an extensive acute cerebral hypoxic injury: A case report

Diffusion-weighted (DW) MR imaging usually identifies acute cerebral infarction injury in symptomatic patients. We report a patient with severe hypoxic brain injury following suicide attempt by hanging, but with normal DW MR imaging 5–6 h after the event. Follow-up DW MR imaging 3 days after the event, and subsequent autopsy, revealed extensive cerebral anoxic injury.

MRI and neurological findings in patients with spinal metastases

BACKGROUND

Magnetic resonance imaging (MRI) is the recommended primary investigation method for metastatic spinal cord compression (MSCC). Initiating treatment before the development of motor deficits is essential to preserve neurological function. However, the relationship between MRI-assessed grades of spinal metastatic disease and neurological status has not been widely investigated.

PURPOSE

To analyze the association between neurological function and MRI-based assessment of the extent of spinal metastases using two different grading systems.

MATERIAL AND METHODS

A total of 284 patients admitted to our institution for initial radiotherapy or surgery for symptomatic spinal metastases were included in the study. Motor and sensory deficits were categorized according to the Frankel classification system. Pre-treatment MRI evaluations of the entire spine were scored for the extent of spinal metastases, presence and severity of spinal cord compression, and nerve root compression. Two MRI-based scales were used to evaluate the degree of cord compression and spinal canal narrowing and relate these findings to neurological function.

RESULTS

Of the patients included in the study, 28 were non-ambulatory, 49 were ambulatory with minor motor deficits, and 207 had normal motor function. Spinal cord compression was present in all patients with Frankel scores of B or C, 23 of 35 patients with a Frankel score of D (66%), and 48 of 152 patients with a Frankel score of E (32%). The percentage of patients with severe spinal canal narrowing increased with increasing Frankel grades. The grading according to the scales showed a significant association with the symptoms according to the Frankel scale (P < 0.001).

CONCLUSION

In patients with neurological dysfunction, the presence and severity of impairment was associated with the epidural tumor burden. A significant number of patients had radiological spinal cord compression and normal motor function (occult MSCC).

Low frequency of VHL germline mutations in Norwegian patients presenting with isolated central nervous system hemangioblastomas--a population-based study

OBJECTIVES

Explore the genetic and clinical incidence of von Hippel-Lindau disease in patients presenting with isolated central nervous system hemangioblastomas.

RESULTS

We report a 3.2% (1/31) and 25% (8/32) incidence of genetic and clinical VHL, respectively. One patient tested positive for a VHL mutation that has not previously been reported. This genotype phenotypically predicts VHL type 2B. We had seven patients with renal cysts. In a total follow-up of 33 person years, none of these cysts progressed to renal cell carcinoma.

CONCLUSION

von Hippel-Lindau disease anchored in germline mutations of the VHL gene is rare in the Norwegian population as opposed to clinical VHL disease, which appears to be relatively common in patients with apparently sporadic hemangioblastomas. There exists insufficient data regarding the natural history of patients with renal cysts, which makes it difficult to include or disregard these lesions as an entity of VHL disease.

Dural ectasia in Marfan syndrome: a case control study

BACKGROUND AND PURPOSE

Dural ectasia (DE) is one of the major criteria of Marfan syndrome (MFS). Our aim was to establish the prevalence of DE in an adult population fulfilling the Ghent criteria for MFS and to assess definitions of DE.

MATERIALS AND METHODS

One hundred five adults with suspected MFS were included. MR imaging at 1.5T was performed unless contraindicated; then CT was obtained. Lumbosacral anteroposterior vertebral body diameters (VBD) and dural sac diameters (DSD) were measured. Dural sac ratios (DSR = DSD/VBD) at levels L3 through S1 were calculated. Anterior meningoceles, herniations of nerve root sleeves, and scalloping were characterized. One hundred one sex- and age-matched patients were included as controls.

RESULTS

We identified 3 patient groups: 1) fulfilling Ghent criteria independent of DE (n = 73), 2); fulfilling Ghent criteria dependent on DE (n = 14), and 3); and suspected MFS, not fulfilling Ghent criteria (n = 18). DE was found in 86% of group 1. At levels L4-S1, mean DSRs were significantly higher in group 1 than in group 3 and controls (P < .001). Herniations of the nerve root sleeves were present in 73% in group 1 versus 1% in controls. Anterior meningoceles were found in 37% and 14% in groups 1 and 2, respectively, but not in group 3 or controls.

CONCLUSIONS

The diagnosis of DE on MR imaging or CT should be based on the presence of at least 1 of the following criteria: anterior meningoceles or nerve root sleeve herniation, DSD at S1 or below larger than DSD at L4, and DSR at S1 >0.59.

A piglet model for detection of hypoxic-ischemic brain injury with magnetic resonance imaging

Munkeby BH, de Lange C, Emblem KE, Bjørnerud A, Kro GAB, Andresen J, Winther-Larssen EH, Løberg EM, Hald JK. A piglet model for detection of hypoxic-ischemic brain injury with magnetic resonance imaging. Acta Radiol 2008;49:1049–1057.

Histogram analysis of MR imaging-derived cerebral blood volume maps: combined glioma grading and identification of low-grade oligodendroglial subtypes

BACKGROUND AND PURPOSE

Inclusion of oligodendroglial tumors may confound the utility of MR based glioma grading. Our aim was, first, to assess retrospectively whether a histogram-analysis method of MR perfusion images may both grade gliomas and differentiate between low-grade oligodendroglial tumors with or without loss of heterozygosity (LOH) on 1p/19q and, second, to assess retrospectively whether low-grade oligodendroglial subtypes can be identified in a population of patients with high-grade and low-grade astrocytic and oligodendroglial tumors.

MATERIALS AND METHODS

Fifty-two patients (23 women, 29 men; mean age, 52 years; range, 19-78 years) with histologically confirmed gliomas were imaged by using dynamic susceptibility contrast MR imaging at 1.5T. Relative cerebral blood volume (rCBV) maps were created, and 4 neuroradiologists defined the glioma volumes independently. Averaged over the 4 observers, a histogram-analysis method was used to assess the normalized histogram peak height of the glioma rCBV distributions.

RESULTS

Of the 52 patients, 22 had oligodendroglial tumors. The histogram method was able to differentiate high-grade gliomas (HGGs) from low-grade gliomas (LGGs) (Mann-Whitney U test, P < .001) and to identify low-grade oligodendroglial subtypes (P = .009). The corresponding intraclass correlation coefficients were 0.902 and 0.801, respectively. The sensitivity and specificity in terms of differentiating low-grade oligodendroglial tumors without LOH on 1p/19q from the other tumors was 100% (6/6) and 91% (42/46), respectively.

CONCLUSION

With histology as a reference, our results suggest that histogram analysis of MR imaging-derived rCBV maps can differentiate HGGs from LGGs as well as low-grade oligodendroglial subtypes with high interobserver agreement. Also, the method was able to identify low-grade oligodendroglial tumors without LOH on 1p/19q in a population of patients with astrocytic and oligodendroglial tumors.

Delayed diffusion-weighted MR abnormality in a patient with an extensive acute cerebral hypoxic injury

Diffusion-weighted (DW) MR imaging usually identifies acute cerebral infarction injury in symptomatic patients. We report a patient with severe hypoxic brain injury following suicide attempt by hanging, but with normal DW MR imaging 5-6 h after the event. Follow-up DW MR imaging 3 days after the event, and subsequent autopsy, revealed extensive cerebral anoxic injury.

Improving postoperative MR imaging of pituitary macroadenomas: comparison of full and reduced dose of gadopentetate dimeglumine

The aim of this study was to evaluate the efficacy of contrast-medium (CM)-ehanced MR imaging of operated pituitary macroadenomas with reduced dose of gadopentetate dimeglumine. In a prospective study 18 patients were examined with coronal T1-weighted MR imaging prior to and following intravenous CM injections. Two sets of contrast-enhanced coronal images were obtained in each patient; the first set after 50% of the recommended dose of 0.1 mmol/kg body weight (b.w.) had been administered, and the second set immediately after additional CM had been given to make up a total dose of 0.1 mmol/kg b.w. The images were evaluated by three neuroradiologists. The SIPAP classification system was used to evaluate tumour extension, whereas tumour margin conspicuity was scored using an arbitrary scale of 1-5 (1 = indistinct, 5 = well defined). Signal intensity measurements obtained from the most enhancing part of the adenomas demonstrated increased enhancement with increased CM dose. Tumour delineation scores were significantly better on the reduced- and full-dose images than on pre-CM injection images, but, with one exception, tumour extension was identified as the same on all imaging sequences. Postoperative MR imaging of large macroadenoma residues can routinely be performed without intravenous CM. When CM is indicated a reduced dose of gadopentetate dimeglumine should provide sufficient diagnostic information.

CTA in patients with acute subarachnoid haemorrhage. A comparative study with selective, digital angiography and blinded, independent review

PURPOSE

Minimal- or non-invasive methods replacing intra-arterial digital subtraction angiography (IA-DSA) would be of great importance in patients suffering from acute subarachnoid haemorrhage (SAH). The aims of this study were to compare CTA with IA-DSA in patients with acute SAH, to compare CTA interpretations with those of blinded, independent reviewers and to evaluate improvement in CTA diagnostics after 1 year of experience with CTA.

MATERIAL AND METHOD

During 2 years 162 patients with SAH underwent CTA as well as IA-DSA. Independent blinded review of 77 patients was performed for 1 year.

RESULTS

Totally 144 aneurysms were demonstrated in 119 patients at IA-DSA, while 43 patients had normal intracranial arteries. Initially 131 aneurysms were detected at CTA while 2 normal, tortuous arteries were misinterpreted as aneurysms, giving a sensitivity of 91% and a specificity of 95%. At independent blinded review the observer agreement was 87% and the kappa value 0.68.

CONCLUSION

CTA in SAH is of great value in demonstrating vascular anatomy and the exact size of an aneurysm. However, IA-DSA is still needed for diagnostic evaluation in aneurysms smaller than 5 mm in diameter, especially in those located near bony structures.

[Neurologic magnetic resonance tomography--indications and practical use]

Magnetic resonance tomography is considered the most important technique in modern neuroradiology. This article demonstrates the importance of MR imaging in the diagnosis of diseases of the central nervous system. Modern neuroradiology is completely dependent upon this modality, and sections and departments of neuroradiology should have great responsibility for both diagnostic MR imaging and the day-to-day operation MR laboratories.

Craniopharyngioma: radiologic and histologic findings and recurrence

PURPOSE

To identify the CT and MR characteristics of craniopharyngiomas, to evaluate the histologic types of craniopharyngioma, and to compare the radiologic/histologic appearance and type of therapy with tumor recurrence.

METHODS

We reviewed the records of 45 patients with craniopharyngiomas for which surgical specimens (n = 45), preoperative MR or CT studies (n = 27), or other MR or CT studies or reports (n = 18) were available. Radiologic appearance, histologic morphology, treatment, and tumor recurrence were studied.

RESULTS

Adamantinomatous epithelium was found in 40 of 45 surgical specimens, keratin in 34 of 45, and squamous epithelium in 11 of 45. A continuum of mixed morphology rather than distinct subtypes of tumors was found. The radiologic appearance did not correlate with the histologic features. No statistically significant difference was found between children and adults with respect to tumor size, calcification, histology, or tumor recurrence. Patients treated with radiation after subtotal resection had far fewer tumor recurrences (n = 3) than patients treated with surgery alone (n = 18).

CONCLUSION

Craniopharyngiomas could not be divided into distinct histologic types. No differentiating radiologic or histologic characteristics could be established for craniopharyngiomas in children versus adults. Radiation treatment was strongly associated with tumor regression or lack of recurrence.

Pre- and postoperative MR imaging of craniopharyngiomas

PURPOSE

To compare the pre- and postoperative MR appearance of craniopharyngiomas with respect to lesion size, tumour morphology and identification of surrounding normal structures.

MATERIAL AND METHODS

MR images obtained prior to and following craniopharyngioma resection were evaluated retrospectively in 10 patients. Tumour signal characteristics, size and extension with particular reference to the optic chiasm, the pituitary gland, the pituitary stalk and the third ventricle were evaluated.

RESULTS

Following surgery, tumour volume was reduced in all patients. In 6 patients there was further tumour volume reduction between the first and second postoperative images. Two of these patients received radiation therapy between the 2 postoperative studies, while 4 had no adjuvant treatment to the surgical intervention. There was improved visualization of the optic chiasm in 3, the pituitary stalk in one, and the third ventricle in 9 of the 10 patients. The pituitary gland was identified preoperatively only in one patient, postoperatively only in another, pre- and postoperatively in 5, and neither pre- nor postoperatively in 3 patients. In 3 patients MR imaging 0-7 days postoperatively identified tumour remnants not seen at the end of the surgical procedure. The signal intensities of solid and cystic tumour components were stable from pre- to the first postoperative MR images. Optic tract increased signal prior to surgery was gone 28 days postoperatively in one patient, but persisted on the left side for 197 days after surgery in another.

CONCLUSION

Postoperative MR imaging of craniopharyngiomas demonstrated tumour volume reduction and tumour remnants not seen at surgery. Early postoperative MR imaging of craniopharyngiomas may overestimate the size of residual tumour. Improved visualization of peritumoral structures may be achieved.

Craniopharyngioma identification by CT and MR imaging at 1.5 T

To compare the detectability of craniopharyngiomas by CT and MR imaging, preoperative CT and MR studies obtained within 16 days of each other were evaluated retrospectively in 9 patients. MR imaging demonstrated cystic and solid tumor components in all 9 tumors, and enhancement in the 7 tumors that were studied after contrast medium injection. MR imaging demonstrated a signal void consistent with calcification in 4 patients. Combining unenhanced and contrast medium-enhanced studies, CT also identified all the tumors. CT demonstrated cysts in 7 lesions, calcification in 7 and enhancement in 6 of the 7 lesions that received i.v. contrast medium. Calcification was better seen by CT than MR imaging, while MR imaging identified cystic tumor components not seen on CT. The contrast medium enhancement pattern was the same with the 2 modalities. MR imaging of the sellar region, including at least one contrast medium-enhanced sequence, should be sufficient in most instances to establish a preoperative diagnosis of craniopharyngioma.

Craniopharyngiomas--the utility of contrast medium enhancement for MR imaging at 1.5 T

To evaluate the efficacy of i.v. contrast medium administration in MR imaging at 1.5 T in patients with craniopharyngiomas, MR studies of 10 men and 6 women with pathologically proven craniopharyngiomas were made. The MR images were obtained as 3- to 5-mm-thick coronal (n = 13) or axial (n = 3) Tl-weighted images (T1WI) prior to and following i.v. Gd-DTPA administration. Proton density- (PD) and T2-weighted images (T2WI) were also obtained. Conspicuity of tumor margins, cystic versus solid components, size, location and effect upon adjacent structures were separately characterized in all imaging sequences. In 6 patients contrast medium-enhanced T1WI. PD and T2WI demonstrated cystic tumor components not seen on unenhanced T1WI. There were significant differences (p < 0.004) on 2-tailed Student's t-test comparing tumor conspicuity on contrast medium-enhanced T1WI with unenhanced T1WI, PD and T2WI. Optimal tumor delineation on MR imaging of patients with craniopharyngiomas justifies the use of i.v. contrast medium.

MR imaging of pituitary region lesions with gadodiamide injection

Twelve patients with known or suspected pituitary lesions underwent MR imaging with gadodiamide injection at a dose of 0.1 (n = 5) or 0.3 (n = 7) mM/kg. Six of the patients were also studied with 0.1 mM/kg gadopentetate dimeglumine. Consistent with previous reports gadodiamide injection was found to be a safe and effective contrast medium for MR imaging of the pituitary region. No additional diagnostic information was obtained using 0.3 mM/kg gadodiamide injection compared to 0.1 mM/kg gadopentate dimeglumine in the same patients. The high dose (0.3 mM/kg) gadodiamide injection in 7 patients did not shorten the T2 value sufficiently to overwhelm the T1 shortening and leave pathologic lesions hypointense compared to precontrast studies. With the comparable relaxivities of gadodiamide injection and gadopentetate dimeglumine, similarities in results have to be expected when using these media for MR image enhancement.

Multiple spinal arteriovenous fistulas in Klippel-Trenaunay-Weber syndrome treated with platinum fibre coils

A 13-year-old girl with Klippel-Trenaunay-Weber syndrome and intradural extramedullary spinal arteriovenous fistulas is presented. Pre-embolization balloon test occlusions and embolization with platinum fibre coils were carried out in three sessions, after which the myelopathy and the intense back pain disappeared. Our conclusion is that spinal fistulas can be safely and effectively treated with fibre coils in combination with balloon testing.

Comparison of 12-bit and 8-bit gray scale resolution in MR imaging of the CNS. An ROC analysis

A reduction in gray scale resolution of digital images from 12 to 8 bits per pixel usually means halving the storage space needed for the images. Theoretically, important diagnostic information may be lost in the process. We compared the sensitivity and specificity achieved by 4 radiologists in reading laser-printed films of original 12-bit MR images and cathode ray tube displays of the same images which had been compressed to 8 bits per pixel using a specially developed computer program. Receiver operating characteristic (ROC) curves showed no significant differences between film reading and screen reading. A paired 2-tailed t-test, applied on the data for actually positive cases, showed that the combined, average performance of the reviewers was significantly better at screen reading than at film reading. No such differences were found for actually negative cases. Some individual differences were found, but it is concluded that gray scale resolution of MR images may be reduced from 12 to 8 bits per pixel without any significant reduction in diagnostic information.

MR imaging of pituitary macroadenomas before and after transsphenoidal surgery

MR findings before and after transsphenoidal surgery were evaluated in 6 cases. T1-weighted (TR/TE 600/20) sagittal and coronal images with 2 or 4 acquisitions were obtained, using 3-mm slice thickness and 0.3-mm interslice gaps. Of 18 MR examinations, 13 included coronal i.v. contrast medium enhanced images. Image quality, sinus cavernosus invasion, identification of normal pituitary tissue and tumor size were examined. All MR studies clearly demonstrated the macroadenomas whether 2 or 4 acquisitions were used, and whether i.v. contrast medium was administered or not. Surgically confirmed sinus cavernosus infiltration was seen in 4 patients. The pituitary stalk was identified separate from the tumor in 2 patients, and the gland in one. There was reduction in tumor size over time, indicating that final radiologic assessment after transphenoidal surgery is best performed 4 to 6 months postoperatively. It should not be necessary to routinely include i.v. contrast medium injection in the postoperative evaluation of macroadenomas.

[Glutaric aciduria type I]

Glutaric aciduria type I is a congenital metabolic disease caused by an enzymatic defect in the degradation of the amino acids lysine and tryptophane. This article presents five Norwegian patients with this condition. Early clinical features may be similar to those of encephalitis. The further clinical course is dominated by choreoathetosis, hyperkinesis and spasticity. The diagnosis is made by tracing enhanced glutaric acid in the urine. The treatment is a low protein diet containing only small quantities of lysine and tryptophane. Four of our patients underwent a neuropsychological examination. Despite the fact that such patients are difficult to test, our examination indicates that the condition has a greater effect on motor than on cognitive functions.

Carotid-cavernous fistula treated with detachable balloon during bilateral transcranial Doppler monitoring of middle cerebral arteries. A case report

A traumatic carotid-cavernous fistula was closed with a silicone detachable balloon. Prior to the closure of the fistula, clinical and transcranial Doppler testing was performed in order to evaluate the consequences of a possible occlusion of the carotid artery. A newly developed Doppler technique with bilateral simultaneous velocity recordings of the middle cerebral arteries was useful during the procedure. The detachable balloon was effective in closing the fistula, but collapse of the balloon and the development of an extradural aneurysm was found at control examinations.

Evaluation of renal function with delayed CT after injection of nonionic monomeric and dimeric contrast media in healthy volunteers

A new nonionic dimeric contrast medium (CM), iodixanol, was intravenously administered to 40 healthy male volunteers in doses of 0.3-1.2 g of iodine per kilogram of body weight, nonionic monomeric iopamidol and iopentol were administered to 20 others, and the renal effects were studied up to 120 hours after administration. Computed tomography of the kidneys was performed up to 80 hours after injection. Creatinine clearance as an index of the glomerular filtration rate was unchanged with all CM. Urine volume and osmolar clearance increased most with the monomeric CM. The proximal tubular brush border enzyme alkaline phosphatase increased with all CM. The lysosomal enzyme N-acetyl-beta-glucosaminidase increased more with the monomeric CM than with iodixanol. A persistent increased attenuation in the region of the cortex was observed with all CM. Attenuation returned to baseline within 80 hours, with the slowest decline with iodixanol. This delayed cortical enhancement did not correlate with the effects of the CM on the tubular enzyme excretion.

Embolization of intracranial arteriovenous malformations and fistulas with polyvinyl alcohol particles and platinum fibre coils

In order to reduce the recanalization rate of arteriovenous malformations and multiple dural arteriovenous fistulas, embolization was carried out with polyvinyl alcohol (PVA) particles combined with platinum fibre coils in 20 patients. The malformation was occluded more effectively than by PVA alone. Distal deposition of the emboli was obtained by improved steerable catheters (Tracker-18-unibody) and guidewires. The complication rate was lower than usually reported from studies using glue as embolic agent. It was concluded that the combination of PVA and fibre coils enhances the safety and effectiveness of embolization therapy and reduces the frequency of recanalization of intracranial AVMs.

Coronal MR imaging of the normal 3rd, 4th, and 5th lumbar and 1st sacral nerve roots

Seven healthy volunteers underwent coronal MR imaging at 1.5 tesla of the normal 3rd, 4th, and 5th lumbar, and 1st sacral nerve roots. Coronal slices, 3-mm-thick with a 0.3-mm gap between the slices were obtained (TR/TE 600/22) through the lumbar spinal canal. All the nerve roots were visible on at least one image. One can routinely expect to demonstrate the 3rd, 4th, and 5th lumbar, and 1st sacral nerve roots on T1-weighted, 3-mm-thick coronal MR scans. We found no correlation between the degree of lumbar lordosis and the lengths of the visible nerve roots. Five patients with one of the following spinal problems: anomaly, tumor, disk herniation, and failed back surgery syndrome were examined according to our protocol. In all these cases coronal MR imaging gave the correct diagnosis.

Bilateral arachnoid cysts of the temporal fossa in four children with glutaric aciduria type I

Glutaric aciduria type I is an uncommon inborn error of metabolism. It is a serious disease, often with a fatal outcome. This study reports the presence of bilateral temporal fluid collections, probably bilateral arachnoid cysts, in association with glutaric aciduria type I. The CT and, when available, MR studies from five patients with this disorder were reviewed. Four of the patients had findings consistent with bilateral arachnoid cysts of the temporal fossa. This is a rare occurrence, with only 11 such cases reported in the literature. The observed association between temporal fluid collections and glutaric aciduria type I suggests that patients with bilateral arachnoid cysts should be investigated for this metabolic disorder.

[Magnetic tomography and backache]

Magnetic resonance imaging (MRI) is a well documented method for diagnosis of spinal disease. We discuss the changes in the number of myelographies and spinal CT examinations carried out at our department after having had our own MRI unit for two years.

MRI in cervical disk herniation

Eleven operated herniated disks in 10 patients were evaluated preoperatively with plain films, myelography and magnetic resonance imaging. Plain X-ray was a valuable supplement to MRI for studying the bony changes. Myelography showed 7 of 11 herniated disks while MRI gave correct diagnosis in all. It is concluded that MRI can replace myelography and computerized tomography in the preoperative evaluation of cervical herniated disk. The other examinations may be supplementary in some cases.

Magnetic resonance imaging of an epidural spinal arachnoid cyst

The myelography, CT and MR imaging findings in a patient with an epidural spinal arachnoid cyst are discussed. MR imaging excellently demonstrated cyst size, cyst location and cord compression, and should be the method of choice in these cases.

Aneurysms of the vein of Galen: embryonic considerations and anatomical features relating to the pathogenesis of the malformation

Vein of Galen aneurysms may be defined as direct arteriovenous fistulas between choroidal and/or quadrigeminal arteries and an overlying single median venous sac. Anatomic analysis of 23 cases of vein of Galen aneurysm and correlation with known embryologic data indicate that the venous sac most probably represents persistence of the embryonic median prosencephalic vein of Markowski, not the vein of Galen, per se. The frequent concurrent venous abnormalities are easily understood as (a) retention of fetal anatomical features and (b) frequent occlusions of the dural sinuses of the posterior fossa, especially the sigmoid sinuses.