The role of MR angiography in the pretreatment assessment of intracranial aneurysms: a comparative study.

BACKGROUND AND PURPOSE: With developments in coil technology, intracranial aneurysms are being treated increasingly by the endovascular route. Endovascular treatment of aneurysms requires an accurate depiction of the aneurysm neck and its relation to parent and branch vessels preoperatively. Our goal was to estimate the clinical efficacy of MR angiography (MRA) in the pretreatment assessment of ruptured and unruptured intracranial aneurysms. We compared MRA source data (axial acquired partitions), multiplanar reconstruction (MPR) of these data, as well as maximum intensity projection (MIP) and 3D-isosurface images with intraarterial digital subtraction angiography (IA-DSA). METHODS: The study was performed in 29 patients with 42 intracerebral aneurysms. The MRA data were examined in four different forms--as axial source data, MPR images of the source data, and MIP and 3D isosurface--rendered images. A composite standard of reference for each aneurysm was then constructed using this information together with the IA-DSA findings by looking at aneurysm detection rate, aneurysm morphology, neck interpretation, and branch vessel relationship to the aneurysm. All techniques, including conventional IA-DSA, were then scored independently on a five-point scale from 1 (non diagnostic) to 5 (excellent correlation with the standard of reference) for each of the aneurysm components as compared with the composite picture. An overall score for each technique was also obtained. RESULTS: Of the 42 aneurysms examined, 34 were small (<10 mm), six were large (10-25 mm), and two were giant (>25 mm). Three aneurysms were not detected with MRA. These were smaller than 3 mm and either in an anatomically difficult location (middle cerebral artery bifurcation) or obscured by adjacent hematoma. Two large aneurysms were depicted as undersized by IA-DSA owing to the presence of intramural thrombus shown by MRA axial source data. IA-DSA received the highest scores overall and in three of the four subgroups. Three-dimensional isosurface reconstructions scored higher than did IA-DSA for depiction of the aneurysm neck, although this difference was not significant. The MPR and 3D-isosurface images were comparable to those of IA-DSA in all categories. MPR images were particularly useful for defining branch vessels and the aneurysm neck. MIP images scored poorly in all subgroups (P < .005) compared with IA-DSA findings, except for in aneurysm detection. Source data images were significantly inferior to those of IA-DSA in all categories (P < .005). CONCLUSION: MRA is currently inferior to IA-DSA in pretreatment assessment of intracranial aneurysms, and can miss small lesions (<3 mm). It can, however, provide complementary information to IA-DSA, particularly in anatomically complex areas or in the presence of intramural thrombus. If MRA is used in aneurysm assessment, a meticulous technique with reference to both axial source data and MPR is mandatory. The axial source data should not be interpreted in isolation. Three-dimensional isosurface images are comparable to those of IA-DSA and are more reliable than are MIP images, which should be interpreted with caution.

Comparison of three-dimensional visualization techniques for depicting the scala vestibuli and scala tympani of the cochlea by using high-resolution MR imaging.

BACKGROUND AND PURPOSE: Cochlear implantation requires introduction of a stimulating electrode array into the scala vestibuli or scala tympani. Although these structures can be separately identified on many high-resolution scans, it is often difficult to ascertain whether these channels are patent throughout their length. The aim of this study was to determine whether an optimized combination of an imaging protocol and a visualization technique allows routine 3D rendering of the scala vestibuli and scala tympani. METHODS: A submillimeter T2 fast spin-echo imaging sequence was designed to optimize the performance of 3D visualization methods. The spatial resolution was determined experimentally using primary images and 3D surface and volume renderings from eight healthy subjects. These data were used to develop the imaging sequence and to compare the quality and signal-to-noise dependency of four data visualization algorithms: maximum intensity projection, ray casting with transparent voxels, ray casting with opaque voxels, and isosurface rendering. The ability of these methods to produce 3D renderings of the scala tympani and scala vestibuli was also examined. The imaging technique was used in five patients with sensorineural deafness. RESULTS: Visualization techniques produced optimal results in combination with an isotropic volume imaging sequence. Clinicians preferred the isosurface-rendered images to other 3D visualizations. Both isosurface and ray casting displayed the scala vestibuli and scala tympani throughout their length. Abnormalities were shown in three patients, and in one of these, a focal occlusion of the scala tympani was confirmed at surgery. CONCLUSION: Three-dimensional images of the scala vestibuli and scala tympani can be routinely produced. The combination of an MR sequence optimized for use with isosurface rendering or ray-casting algorithms can produce 3D images with greater spatial resolution and anatomic detail than has been possible previously.

Combined fat- and water-suppressed MR imaging of orbital tumors.

BACKGROUND AND PURPOSE: The use of a high-resolution T2-weighted MR sequence, which suppresses signal from both fat and water, has been shown to be highly effective for depicting areas of inflammatory damage within the optic nerve. The ability of this sequence to show neoplastic and inflammatory orbital lesions, which may mimic neuritis, is unknown. This study was designed to examine the characteristics of such a sequence for the investigation of orbital mass lesions. METHODS: Twenty-eight patients with known or suspected mass lesions of the orbit and six healthy volunteers were recruited for study. Imaging was performed with a 1.5-T MR unit. Participants were examined by selective partial inversion recovery (SPIR) sequences with T2-weighted fast spin-echo acquisition, selective partial inversion recovery/fluid attenuated inversion recovery (SPIR/FLAIR) sequences with fast spin-echo acquisition, short tau inversion recovery (STIR) sequences with fast spin-echo acquisition, and SPIR sequences with contrast-enhanced T1-weighted fast spin-echo acquisition. Two neuroradiologists, using a randomised, blinded method, scored images for lesion presence and extent. Lesion extent was defined as the number of images with visible abnormality, and was compared with the standard of reference established at a later date by consensus review of all imaging sequences. The ability of the sequences to show the presence and extent of pathologic lesions was compared. RESULTS: The SPIR/FLAIR sequence showed both the presence and extent of orbital masses significantly better than did either STIR or T2-weighted SPIR sequences (P<.01 and P<.001, respectively). Contrast-enhanced T1-weighted SPIR images ranked better than SPIR/FLAIR images, although the difference failed to reach statistical significance. In the orbital apex, the SPIR/FLAIR technique was superior to all other techniques used. This reflected its ability to distinguish enhancing, pathologic lesions from enhancing, normal anatomy. CONCLUSION: SPIR/FLAIR is an appropriate screening technique for orbital masses and offers significant advantages over currently used fat-suppressed sequences for the investigation of orbital disease.

Memory dysfunction in multiple sclerosis corresponds to juxtacortical lesion load on fast fluid-attenuated inversion-recovery MR images.

BACKGROUND AND PURPOSE: MR imaging is a sensitive diagnostic tool and paraclinical marker of disease activity and prognosis in multiple sclerosis (MS), yet the role of MR imaging of MS is controversial. The aim of this study was to describe the relationship between cognitive function and MS lesion size and position, as shown on comparative images from conventional spin-echo (CSE) and fast fluid-attenuated inversion-recovery (fast FLAIR) MR studies. METHODS: CSE and fast FLAIR sequences consisted of 40 noncontiguous, 3-mm-thick axial sections matched for geometric position in 18 patients with relapsing-remitting MS. Lesions were scored for size, anatomic position, and their comparative appearance on CSE and fast FLAIR images. The neuropsychological assessment tested general psychological performance, memory, and frontal lobe executive function. RESULTS: Fast FLAIR images showed significantly more small (146 versus six) and medium-sized (18 versus four) juxtacortical lesions than did CSE sequences. Small juxtacortical lesions displayed only on fast FLAIR images had a distinctive appearance, suggestive of small areas of perivascular inflammation. The number of these lesions corresponded to reduced performance on the fifth and delayed trials of the Rey Auditory Verbal Learning memory function test. CONCLUSION: Fast FLAIR images show small lesions at the juxtacortical boundary that are not seen on CSE studies. The presence of such lesions correlates with impaired retention of information in memory tasks, which is characteristic of cognitive problems in patients with MS.

The value of the short tau inversion recovery sequence in magnetic resonance imaging of thyroid eye disease.

22 patients with thyroid eye disease were examined with magnetic resonance imaging (MRI) and the results compared with 10 controls. Imaging was performed on a 1.0 T scanner using a head coil. All patients were examined using both T1W and short tau inversion recovery (STIR) sequences. The relative signal intensity (SI) of individual extraocular muscles were quantified by comparison with SI from the adjacent temporalis muscle to give a signal intensity ratio (SIR). The results were compared with clinical disease activity assessed by the Werner grading system. Visual evaluation of muscle size and calculated SIRs showed an increase when compared to normals in 15 of the 22 patients. This difference was significant in patients with high grade (4-6) clinical disease. The known histological changes in this disease suggest that this increase in signal is caused by oedema secondary to acute inflammation. STIR sequences suppress the retro-orbital fat and thus enhance these changes both in the muscles and in the fat itself. The MR findings suggest that the STIR sequence can be used to predict those patients that will respond to anti-inflammatory treatment.

Tinnitus as the presenting symptom in a case of Lhermitte-Duclos disease.

Dysplastic gangliocytoma or Lhermitte-Duclos disease (LDD) is a hamartomatous malformation of the cerebellar hemisphere that usually presents with signs of increased intracranial pressure or symptoms of cerebellar dysfunction. In this paper, we report a case of LDD presenting with tinnitus, and postulate a probable mechanism for this unusual presentation.

Magnetic resonance imaging in the investigation of sensorineural hearing loss: is contrast enhancement still necessary?

High resolution T2-weighted magnetic resonance (MR) imaging has been proposed as a rapid, inexpensive means of investigating patients with sensorineural deafness, particularly to exclude vestibular schwannomas. Whether the accepted 'gold standard' of contrast-enhanced T1-weighted images can be omitted, however, remains controversial. Over a 22-month period the use of axial turbo-spin echo T2-weighted images (T2W) were prospectively compared with contrast-enhanced T1-weighted spin echo scans in the evaluation of 513 patients presenting with audiovestibular symptoms. A 2-D T2W turbo spin echo (TSE) sequence with 3 mm slices was used in 340 patients while a 3-D sequence with overlapping 1 mm slices was used in 173 patients. The T2-weighted image findings were documented and subsequently compared with contrast-enhanced images. With the 2-D sequence 24 patients (25 lesions) had internal auditory meatus (IAM)/cerebello-pontine angle (CPA) masses identified by contrast-enhanced T1-weighted images, all of which were seen on the T2-weighted TSE sequence; there was one false positive 'mass' on the T2-weighted scans and one false negative case of IAM dural enhancement on T1-weighted imaging; six were considered normal initially on the T2-weighted images although three were subtly abnormal in retrospect. With the 3-D sequence three acoustic neuromas were all identified correctly with no false positive and only one false negative result (labyrinthitis). The 2-D and 3-D images were judged technically inadequate for clinical assessment in 15 and nine per cent respectively. We conclude that mass lesions of the IAM/CPA can be reliably identified on T2W TSE imaging but labyrinthine lesions may be missed without contrast enhancement. This is of particular importance in planning the management of neurofibromatosis type 2. Non-neoplastic disorders of the inner ear are also likely to be missed.

A case of superficial recurrent ophthalmic artery supplying an infratentorial vascular tumour.

SUMMARY: We present a case of ophthalmic artery contribution to a posterior fossa vascular tumour by the superficial recurrent ophthalmic artery. This branch arises from the second portion of the ophthalmic artery and is rarely seen on angiography. We review the anatomy and embryology of this arterial variant. Furthermore, this case illustrates the capacity of the ophthalmic artery to supply posterior fossa neoplasms.

Endovascular treatment of PICA aneurysms.

Endovascular treatment of aneurysms of the posterior inferior cerebellar artery (PICA) avoids manipulation of the brainstem or lower cranial nerves and should therefore carry a lower risk of neurological morbidity than surgical clipping. We reviewed our experience of 23 patients with PICA aneurysms treated by endovascular occlusion with Guglielmi detachable coils and documented their long-term outcome on follow-up. We observed a 28 day procedure-related neurological morbidity of 13% (3/23 patients). One patient suffered permanent neurological complications. There were no procedure-related deaths. None of our patients suffered a re-bleed from their treated aneurysms. Our series shows endovascular treatment of ruptured PICA aneurysms to be safe and effective.

Blunt carotid arterial trauma.

Blunt injury to the carotid arteries in the neck, either by direct or indirect forces, is rare but may produce a devastating outcome with long term morbidity. Injury results in either dissection of the vessel wall or pseudoaneurysm formation. Secondary thromboembolic disease results in cerebral infarction. In a seven year period, from April 1987 to April 1994, 2024 patients with blunt injury to the head and neck were admitted to our institution. In this group eight patients (0.4%) were identified with injury to the carotid arteries, seven with dissection and one with pseudoaneurysm formation. Injury was caused by either hyperextension or lateral hyperflexion of the neck. External signs of trauma to the neck were absent in three patients. In all patients there was an associated head injury. Three suffered transient loss of consciousness and a fourth had a transient ischaemic attack 36 h after the injury. CT brain scans performed at the time of initial injury in these patients were all normal. The remaining four patients had no neurological deficit at initial presentation. In no case was injury to the carotid artery suspected. Focal neurological signs and symptoms developed in all cases following a variable latent period ranging from 4 h to 75 days. CT or MRI at this time revealed areas of cerebral infarction. Diagnosis of carotid injury was made at angiography in all cases. These lesions are treatable if diagnosed prior to the development of extensive infarction. Patients developing focal neurological signs secondary to cerebral infarction after a latent period following head and neck trauma should therefore be considered as having a vascular lesion in the neck and referred for urgent cerebral angiography.

Hereditary spinal osteochondromas in diaphyseal aclasia.

We present cases of cervical cord compression in father and son with diaphyseal aclasia. Both patients were investigated with plain radiography, CT and MRI. We believe this to be the first report of spinal cord compression in first-degree relatives with diaphyseal aclasia.

Significance of CSF area measurements in cervical spondylitic myelopathy.

Mild clinical myelopathy can occur without cord compression, and asymptomatic cord compression seen on MRI is common. The aim of this study was to ascertain the MRI features which best correlate with early clinical myelopathy. The study was conducted on three groups: group A, 20 patients with clinical myelopathy and MRI evidence of cervical spondylosis; group B, 20 patients without myelopathy, but with other clinical and MRI evidence of cervical spondylosis; and group C, 10 normal volunteers with no MRI evidence of spondylosis. The cross-sectional area (CSA) of the spinal cord (SP-CSA), spinal canal (SC-CSA) and CSF space (CSF-CSA) were measured on T1-weighted axial images at the level of the most severe spinal canal stenosis. The severity of myelopathy was assessed using a simple scoring system giving a score from 0 (normal) to 11 (severe). Subjective demonstration of cord compression on sagittal images was an insensitive indicator of clinical myelopathy. All three measures of cross-sectional area were significantly smaller in Group A than in B (p<0.01). The reduction in SP-CSA was the only independent prognosticator for severity of myelopathy (p<0.005) accounting for 63% of the variation in myelopathy score. All three variables showed a significant correlation with the presence of myelopathy (p<0.01); however, logistic regression analysis showed a decrease in CSF-CSA to be the only independent significant prognosticator of the presence of clinical myelopathy (p<0.02). Reduction of the CSF space to less than 0.7 cm2 was associated with a 90% chance of clinical myelopathy (specificity 83%).

Time of Flight 3D Magnetic Resonance Angiography in the Follow-up of Coiled Cerebral Aneurysms.

SUMMARY: The use of Guglielmi Detachable Coil (GDC) for the en do vascular treatment of intracerebral aneurysms is increasing, particularly in those aneurysms for which there is a high surgical morbidity and mortality. However, the long-term efficacy of GDC is not known. Until the natural history of GDC treatment is established longterm follow-up in this cohort of patients is required, of necessity involving repeated intraarterial angiography (IA DSA) with its known attendant risks and exposure to ionising radiation. Three dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) is now readily accepted as a non-invasive screening tool for familial aneurysmal disease and has been used as an alternative to IA DSA in the surgical management of aneurysmal subarachnoid haemorrhage. MRA in patients treated with GDC is safe, imparts no radiation dose and provides acceptable image quality. The aim of this study was to assess 3D TOP MRA source data, maximum intensity projection (MIP) and 3D isosurface reconstruction in comparison to IA DSA in the follow-up of 25 patients treated with GDC. Images were assessed for parent and branch artery flow, the presence of neck recurrence and aneurysm regrowth. There was good correlation for all these features when 3D isosurface MRA and source data were compared with IA DSA. The correlation between MIP MRA and IA DSA was less robust. Additional confidence can be obtained by performing plain films of the skull to demonstrate change in coil ball configuration. MRA has the potential to replace IA DSA in the follow- up of GDC treated cerebral aneurysms.

Sclerosing cholangitis associated with multifocal fibrosis: a case report.

The association of sclerosing cholangitis, retroperitoneal fibrosis, and Riedel's thyroiditis has been reported twice before, and on both occasions the authors successfully used steroids to control the fibrotic process. A further case of fibrosis with this triad of organ involvement in which a combination of surgery and steroid treatment has arrested disease progression is described. This suggests an inappropriate immune response in this type of fibrotic overlap syndrome.

Cystic optic nerve meningioma presenting with acute proptosis.

A 37-year-old woman presented with acute left-sided proptosis. Magnetic resonance imaging demonstrated a solid intraconal mass lesion with an associated 'capping' cyst. This lesion was resected and found on histological examination to be optic nerve sheath meningioma. Small perineural cysts have been reported with optic nerve sheath meningioma but we believe this to be the first reported case of a large peritumoral cyst associated with this type of mass lesion. We speculate on the aetiology of the cyst and the associated acute proptosis.

Familial tumoral calcinosis: association with cerebral and peripheral aneurysm formation.

Two siblings with histologically and radiologically proven tumoral calcinosis presented with cerebral and peripheral aneurysms. The brother died of a ruptured subclavian artery aneurysm after surgical repair of brachial, iliofemoral and coeliac axis aneurysms. Magnetic resonance and catheter angiography in the sister demonstrated marked carotid dysplasia and a left ophthalmic segment aneurysm, not amenable to treatment. We believe this is the first reported case of familial aneurysms in association with tumoral calcinosis.

Use of single-slice thick slab phase-contrast angiography for the diagnosis of dural venous sinus thrombosis.

The aim of this study was to examine the reliability of single-slice phase-contrast angiography (SSPCA) as a rapid technique for the investigation of suspected dural venous sinus occlusion. Images were obtained on 25 normal volunteers to document the accuracy of SSPCA in the demonstration of slow flow states. Normal volunteers were imaged using sagittal and coronal SSPCA (slice thickness 13 cm, matrix 256 x 256, TR 14 ms, TE 7 ms, flip angle 20 degrees, peak velocity encoding rate 30 cm/s). Sinus patency and flow rate were confirmed by measurement of flow in the superior sagittal and transverse sinuses using quantified single-slice phase difference images. Imaging was performed in 50 patients undergoing routine brain scans in order to determine the optimal slice orientation for clinical use. Twenty-one patients with suspected dural venous sinus thrombosis were also investigated with SSPCA and the diagnosis confirmed by one or more alternative imaging techniques. Imaging time was 29 s per acquisition and image quality was good in all cases. Variations in dural sinus patency and flow in normal volunteers were accurately predicted by SSPCA (kappa = 0.92). Use of a single angulated slice (130 mm thick, para-sagittal image angled 30 degrees towards coronal and 30 degrees towards transverse) provided sufficient separation of right- and left-sided venous structures to allow use of a single projection. The presence and extent of sinus occlusions in 14 patients and the absence of thrombosis in 7 were accurately identified by SSPCA. Sensitivity and specificity in this limited study were both 100%. The SSPCA technique takes less than 30 s and provides a reliable and rapid technique for the diagnosis of dural venous sinus thrombosis.

Optic neuritis: MR imaging with combined fat- and water-suppression techniques.

PURPOSE: To examine the benefits of combined fat- and water-suppressed T2-weighted magnetic resonance (MR) images in the diagnosis of optic neuritis. MATERIALS AND METHODS: MR imaging was performed with a 1.5-T unit in five healthy volunteers and 18 patients (21 nerves). All patients had abnormalities of visual evoked potentials and fulfilled the clinical criteria for the diagnosis of optic neuritis. Imaging was performed within 4 weeks of diagnosis (n = 12) or between 3 and 6 months after diagnosis (n = 6). Coronal images were obtained throughout the course of the optic nerve with use of three sequences: (a) short inversion time inversion recovery with fast spin-echo (SE) acquisition, (b) selective partial inversion-recovery (SPIR) prepared T2-weighted fast SE acquisition, and (c) SPIR-fluid-attenuated inversion recovery (FLAIR) with fast SE acquisition. RESULTS: Neuritic segments were demonstrated in all 21 symptomatic nerves. The extent of neuritic involvement (number of images showing abnormality) was significantly greater with the SPIR-FLAIR sequence (P < .01). The contrast ratio between neuritic optic nerve and orbital fat, normal nerve, and cerebral spinal fluid was significantly greater with SPIR-FLAIR than with the other sequences (P < .001). SPIR-FLAIR images also improved demonstration of optic nerve atrophy in chronic neuritis when compared with the other sequences. CONCLUSION: The SPIR-FLAIR sequence offers important advantages over current methods in the demonstration of optic neuritis.