Preoperative evaluation of the deep cerebral veins using 3-tesla magnetic resonance imaging.

BACKGROUND: Surgical treatment of deep-seated tumors such as supratentorial intraventricular and thalamic-pineal-tectal region tumors carries a risk of postoperative deficits due to possible damage to deep cerebral veins including the internal cerebral vein. It is often difficult to identify whether the vessel encountered during surgery needs to be preserved or not through the small operative field. Therefore, preoperative evaluation of deep venous structures is important. We evaluated the usefulness of 3-Tesla magnetic resonance imaging (3 T MRI) for this purpose. METHODS: First, the ability to detect deep venous structures was compared with both 3-dimensional computed tomographical angiography (3D-CTA) and 3 T MRI in patients without any damage to deep venous structures. Images of 7 consecutive patients suffering from insulo-opercular gliomas who underwent both imaging modes for the identification of lateral striate arteries were reconstructed for evaluation of the deep cerebral veins. Subsequently, surgery for tumors at the supratentorial intraventricular and thalamic-pineal-tectal regions was prospectively performed with preoperative evaluation of deep venous system only using 3 T MRI. RESULTS: Information on the deep venous systems acquired by 3 T MRI was as useful as that acquired by 3D-CTA. Until today, we have treated 8 cases of supratentorial intraventricular and thalamic-pineal-tectal region tumors with preoperative evaluation of the deep venous system using 3 T MRI without any morbidity. CONCLUSION: Information on the deep venous system obtained with 3 T MRI aids the surgery of supratentorial intraventricular and thalamic-pineal-tectal region tumors. As the required sequences of 3 T MRI are same as those necessary for the neuronavigation system, and 3 T MRI can be achieved without the use of iodine-based contrast agents, 3 T MRI can be an alternative for preoperative evaluation of the deep venous systems.

Posterior circulation and high prevalence of ischemic stroke among young pediatric patients with Moyamoya disease: evidence of angiography-based differences by age at diagnosis.

BACKGROUND AND PURPOSE: At diagnosis, the primary clinical manifestations of pediatric Moyamoya disease are TIA or CSs. CSs are reported to be more prevalent in younger than in older children. We sought to determine whether age-related differences in clinical manifestations are associated with age-related angiographic differences. MATERIALS AND METHODS: We divided 78 patients diagnosed with Moyamoya disease before 16 years of age into four 4-year age groups and examined the relationships between age at diagnosis and clinical manifestations and angiographic and MR imaging findings. RESULTS: Among the 4 diagnostic age groups, in those younger than 4 years of age, the prevalence of CSs and of infarctions on MR images was highest, and along with severity of steno-occlusive lesions of the PCA, the prevalence was significantly higher than that in the next diagnostic age group (4-7 years), though the severity of steno-occlusive lesions in the ICA and the degree of transdural collaterals did not differ significantly. The prevalence of CSs and infarctions did not differ significantly in the 3 oldest diagnostic age groups, whereas ICA and PCA lesions and transdural collaterals correlated positively with diagnostic age. CONCLUSIONS: The high prevalence of CSs and infarctions in patients diagnosed before 4 years of age is associated with advanced steno-occlusive lesions of the PCA. In patients 4 years of age and older at diagnosis, transdural collaterals develop in parallel with advancement of ICA and PCA lesions, which may contribute to the nearly constant prevalence of CSs.

Usefulness of contrast-enhanced T1-weighted sampling perfection with application-optimized contrasts by using different flip angle evolutions in detection of small brain metastasis at 3T MR imaging: comparison with magnetization-prepared rapid acquisition of gradient echo imaging.

BACKGROUND AND PURPOSE: Early accurate diagnosis of brain metastases is crucial for a patient's prognosis. This study aimed to compare the conspicuity and detectability of small brain metastases between contrast-enhanced 3D fast spin-echo (sampling perfection with application-optimized contrasts by using different flip angle evolutions [SPACE]) and 3D gradient-echo (GE) T1-weighted (magnetization-prepared rapid acquisition of GE [MPRAGE]) images at 3T. MATERIALS AND METHODS: Sixty-nine consecutive patients with suspected brain metastases were evaluated prospectively by using SPACE and MPRAGE on a 3T MR imaging system. After careful evaluation by 2 experienced neuroradiologists, 92 lesions from 16 patients were selected as brain metastases. We compared the shorter diameter, contrast rate (CR), and contrast-to-noise ratio (CNR) of each lesion. Diagnostic ability was compared by using receiver operating characteristic (ROC) analysis. Ten radiologists (5 neuroradiologists and 5 residents) participated in the reading. RESULTS: The mean diameter was significantly larger by using SPACE than MPRAGE (mean, 4.5 +/- 3.7 versus 4.3 +/- 3.7 mm, P = .0014). The CR and CNR of SPACE (mean, 57.3 +/- 47.4%, 3.0 +/- 1.9, respectively) were significantly higher than those of MPRAGE (mean, 37.9 +/- 41.2%, 2.6 +/- 2.2; P < .0001, P = .04). The mean area under the ROC curve was significantly larger with SPACE than with MPRAGE (neuroradiologists, 0.99 versus 0.88, P = .013; residents, 0.99 versus 0.78, P = .0001). CONCLUSIONS: Lesion detectability was significantly higher on SPACE than on MPRAGE, irrespective of the experience of the reader in neuroradiology. SPACE should be a promising diagnostic technique for assessing brain metastases.

The leptomeningeal "ivy sign" on fluid-attenuated inversion recovery MR imaging in Moyamoya disease: a sign of decreased cerebral vascular reserve?

BACKGROUND AND PURPOSE: Moyamoya disease is an idiopathic occlusive cerebrovascular disorder with abnormal microvascular proliferation. We investigated the clinical utility of leptomeningeal high signal intensity (ivy sign) sometimes seen on fluid-attenuated inversion recovery images in Moyamoya disease. MATERIALS AND METHODS: We examined the relationship between the degree of the ivy sign and the severity of the ischemic symptoms in 96 hemispheres of 48 patients with Moyamoya disease. We classified each cerebral hemisphere into 4 regions from anterior to posterior. In 192 regions of 24 patients, we examined the relationship between the degree of the ivy sign and findings of single-photon emission CT, including the resting cerebral blood flow (CBF) and cerebral vascular reserve (CVR). RESULTS: The degree of the ivy sign showed a significant positive relationship with the severity of the ischemic symptoms (P < .001). Of the 4 regions, the ivy sign was most frequently and prominently seen in the anterior part of the middle cerebral artery region. The degree of the ivy sign showed a negative relationship with the resting CBF (P < .0034) and a more prominent negative relationship with the CVR (P < .001). CONCLUSIONS: The leptomeningeal ivy sign indicates decreased CVR in Moyamoya disease.

Virtually peeling off the skull and scalp: a simple way of mapping the superficial cerebral veins on the brain surface.

PURPOSE: A simple MRI postprocessing technique was developed to display superficial cerebral veins (SCVs) along with brain surface structures. MATERIALS AND METHODS: Thirty-one consecutive patients with brain tumors were studied. All patients underwent brain MR examination, from which three-dimensional (3D) images were reconstructed. Simulation images of craniotomy were created by cutting away the signal from the skull and scalp at the region corresponding to the window planned for surgery. Detectability of the SCVs was evaluated by comparing the simulation images with intraoperative photographs. Reasons for those undetectable SCVs on simulation images of craniotomy were discussed. RESULTS: Detectability of the SCVs >2 mm was 100%; those from 1 to 2 mm was 88.5%, and those from 0.5 to 1 mm 56.9%. Effacement of cortical sulci/subarachnoid space around the supposed craniotomy site, dural/meningeal contrast enhancement and insufficient spatial resolution of the source images were regarded as the main reasons for undetectable SCVs. CONCLUSION: Virtually peeling off the skull and scalp well demonstrates the SCVs along with brain surface structures. This simple technique can provide useful information about the SCVs and their relationships with cortical structures and tumors for preoperative surgical planning.

Pseudo-subarachnoid hemorrhage found in patients with postresuscitation encephalopathy: characteristics of CT findings and clinical importance.

BACKGROUND AND PURPOSE: High-attenuation areas (HDAs) called pseudo-subarachnoid hemorrhages (SAHs) may develop in some patients resuscitated from cardiopulmonary arrest (CPA), though no hemorrhage has occurred. We investigated the imaging characteristics and clinical significance of this phenomenon. MATERIALS AND METHODS: CT images of consecutive patients resuscitated from nontraumatic CPA were reviewed and classified into cases with pseudo-SAH (pseudo-SAH[+] group, n = 9), those without pseudo-SAH (pseudo-SAH[-] group, n = 28), and those with true SAH (SAH-CPA group, n = 8). Typical patients with SAH (SAH group, n = 13) and 20 healthy individuals were also extracted as control groups. The degree of brain edema was scored visually as none, mild, or severe, and the CT values of the HDAs and brain parenchyma were measured. These parameters were compared among the groups. We also compared the prognosis between the pseudo-SAH(+) and pseudo-SAH(-) groups. RESULTS: On CT, pseudo-SAH was associated with severe brain edema, whereas there was mild or no edema without pseudo-SAH. The CT values of the HDAs in the pseudo-SAH(+) group were significantly lower than those of the CPA-SAH and SAH groups (P < .0001). The brain parenchyma of the pseudo-SAH(+) group had the lowest CT values among all of the groups (P < .0001). The prognosis of the pseudo-SAH(+) group was significantly poorer than that of the pseudo-SAH(-) group in terms of both clinical outcome (P = .02) and survival (P = .046). CONCLUSION: The findings of pseudo-SAH have several imaging characteristics differing from SAH and predict a poor prognosis. This provides important information that can be used for deciding treatment strategies.

Subcortical calcification on CT in dural arteriovenous fistula with cortical venous reflux.

We report 3 cases of dural arteriovenous fistula (dAVF) with cortical venous reflux (CVR) presenting calcification in the cortico-medullary junction at the bottom of cerebral sulci on unenhanced CT. This likely results from chronic venous congestion with resulting impaired perfusion of the involved parenchyma. dAVF with CVR, which is known to have poor prognosis without treatment, should be included in the differential diagnosis of subcortical calcification on CT.

Mild renal insufficiency is associated with reduced coronary flow in patients with non-obstructive coronary artery disease.

Patients with chronic kidney disease (CKD) have increased risk for cardiovascular events. However, the association between these pathophysiological processes is unclear. Therefore, this study was designed to determine the association between early CKD and coronary microvascular disease in patients with normal or mildly diseased coronary arteries. A total of 605 patients with normal or mildly diseased coronary arteries based on angiography underwent coronary flow reserve (CFR) evaluation using intracoronary adenosine. Patients were divided based on glomerular filtration rate (GFR). CKD was defined as calculated GFR<60 ml/min/1.73 m(2). Patients with normal GFR (> or =60 ml/min/1.73 m(2), n=481) had higher CFR compared to those with CKD (n=124, CFR=3.0+/-0.8 vs 2.6+/-0.6, P<0.001, respectively). Patients with abnormal GFR were more likely to be older and of female gender, with greater prevalence of hypertension. Multiple logistic regression analysis adjusted for the aforementioned risk factors further supported the observed relationship. The current study shows that reduced renal function is associated with attenuated coronary vasodilator capacity in patients without obstructive coronary artery disease. The correlation between low GFR and reduced CFR may suggest parallel alterations in the renal and coronary microcirculation at the early stage of disease. Impairment in both microcirculatory beds may reflect an unmeasured risk factor induced by blunted renal function and add a burden to the increased propensity for cardiovascular events in CKD.

Prediction of the origin of intracanalicular neoplasms with high-resolution MR imaging.

Correct diagnosis of intracanalicular neoplasms is important to avoid unnecessary operations or an unsuitable surgical approach. We investigated the capability of high-resolution three-dimensional MR imaging in predicting the origin of intracanalicular neoplasms. Twenty cases underwent three-dimensional Fourier-transformation (3DFT) constructive interference in steady state and contrast-enhanced 3DFT-fast low angled shot MR imaging and surgery. Seventeen cases underwent caloric test. MR diagnosis on the origin of intracanalicular neoplasms was compared with surgical results. For MR diagnosis, the origin of intracanalicular neoplasms was predicted according to the location of the tumor in the internal auditory canal (IAC) in two ways, i.e., determining (1) a single specific nerve of origin and (2) whether the tumor originated from the superior or inferior aspect of the IAC. Surgery could determine the nerve of origin in 16 cases (14 inferior and 2 superior vestibular schwannomas), but it was indeterminate in 4. Comparison between MR prediction and surgical results on a single nerve origin revealed exact agreement in five, but inconsistent in three. Regarding whether the tumor was derived from superior or inferior aspect of the IAC, agreement was found in 10 of the 16 cases (62.5%). Caloric test was abnormal in all patients examined but one with superior vestibular schwannoma. 3DFT-MR imaging was not particularly useful in predicting a precise nerve of origin of intracanalicular neoplasms. The prediction on whether the tumor originated in the superior or inferior aspect of the IAC was superior to caloric test, which might have clinical significance in treatment planning especially for hearing preservation surgery.

Combined three-dimensional anisotropy contrast imaging and magnetoencephalography guidance to preserve visual function in a patient with an occipital lobe tumor.

OBJECTIVE: Three-dimensional anisotropy contrast (3-DAC) magnetic resonance imaging and magnetoencephalography (MEG) of visually evoked magnetic fields (VEFs) were used to accurately localize the optic radiation and primary visual cortex before surgery for an occipital tumor. PATIENT AND METHODS: A 26-year-old male presented with an occipital lobe tumor located intrinsically underneath the right calcarine fissure. 3-DAC imaging showed that the right optic radiation was located along the superior and lateral surfaces of the lesion. Mapping of the VEFs demonstrated that the primary visual cortex was located superior and lateral to the lesion. The lesion was totally resected via an infero-medial cortical incision using a frameless stereotactic system. Histopathology indicated a pilocytic astrocytoma. No visual deficit was found before or after surgery. CONCLUSION: Combined 3-DAC imaging and MEG can provide essential information about the optic radiation and primary visual cortex for planning the surgical treatment of occipital lobe tumors.

Diffusion-weighted MRI abnormalities as an early diagnostic marker for Creutzfeldt-Jakob disease.

OBJECTIVE: To evaluate the usefulness of diffusion-weighted MRI (DWI) for the early diagnosis of Creutzfeldt-Jakob disease (CJD). METHODS: Thirty-six consecutive patients (age 56 to 82 years) were enrolled, and 26 were examined by DWI. Nine were definite based on the World Health Organization criteria, and 27 were probable. The percentages of DWI abnormalities, periodic sharp wave complexes (PSWCs) on the EEG, detection of CSF 14-3-3 protein, and increase of CSF neuron-specific enolase (>25 ng/mL) on the first examination were compared. For DWI, 32 patients (age 31 to 84 years) who showed progressive dementia or impaired consciousness served as disease controls. RESULTS: The percentage of DWI abnormalities was 92.3%, of PSWCs 50.0%, of 14-3-3 protein detection 84.0%, and of NSE increase 73.3%. Two of the 32 control subjects were falsely positive on DWI. The sensitivity of DWI was 92.3% (95% CI 74.8 to 99.5%) and specificity 93.8% (95% CI 79.2 to 99.2%). In 17 patients who did not show PSWCs on the first EEG, abnormal DWI findings were still clearly detected. Four patients who were negative for 14-3-3 protein also showed DWI abnormalities. DWI abnormalities were detected as early as at 3 weeks of symptom duration in four patients in whom PSWCs were not yet evident. CONCLUSIONS: DWI can detect characteristic lesions in the majority of patients with CJD regardless of the presence of PSWCs. DWI was the most sensitive test for the early clinical diagnosis of CJD; consideration should be given to its inclusion in the clinical diagnostic criteria of CJD.

CSF hypovolemia vs intracranial hypotension in "spontaneous intracranial hypotension syndrome".

OBJECTIVES: To investigate the role of CSF hypovolemia in spontaneous intracranial hypotension (SIH) syndrome because so-called SIH syndrome sometimes lacks intracranial hypotension. METHODS: Ten women (aged from 28 to 49 years) with characteristic orthostatic headache without a previous history of dural tear were investigated. In addition to gadolinium (Gd)-enhanced brain MRI, spinal MRI with and without Gd enhancement was performed. RESULTS: Gd-enhanced brain MRI demonstrated diffuse pachymeningeal enhancement in all patients. Sagittal T2-weighted spinal MRI revealed a variable amount of CSF in the extradural space in all patients. Sagittal T2-weighted MRI or axial Gd-enhanced T1-weighted MRI showed dilated epidural veins located in the high cervical portion in each patient. The intensity of dilatation of the epidural veins correlated significantly with the amount of CSF in the epidural space. This suggested that the Monro-Kellie doctrine was applicable in this circumstance. CONCLUSIONS: Since some patients with SIH syndrome have normal CSF pressure and since a downward displacement of the brain due to a reduction of the buoyant action of CSF may induce symptoms, CSF hypovolemia, not intracranial hypotension, may be the cause. Based on the Monro-Kellie doctrine, detecting leaked CSF and venous engorgement (epidural vein dilatation and pachymeningeal enhancement) is an important clue to diagnose so-called SIH syndrome. Dilatation of epidural veins suggests CSF hypovolemia in appropriate conditions.

A case of frontal network amnesia.

A 63 year old man developed an amnesic syndrome coupled with an array of "frontal lobe" signs after bilateral small subcortical infarcts. His amnesia was characterised by severe difficulty in voluntary recall of recently memorised verbal and non-verbal materials, while his recognition for the same materials was less affected. The symptoms remained unimproved at a follow up evaluation eight months after onset. Magnetic resonance imaging showed two small circumscribed lesions, one in the dorsomedial nucleus of the left thalamus and the other in a region of the right globus pallidus and anterior limb of the right internal capsule. The mammillothalamic tracts and anterior nuclei of the thalami were clearly spared bilaterally. The left dorsomedial nucleus lesion disrupted the thalamofrontal circuit, while the anterior limb lesion of the right internal capsule disconnected the same circuit by damaging part of the anterior thalamic radiation. Thus the amnesia in this patient may have been caused by disruption of the bilateral thalamofrontal circuits. This type of amnesic pathology should be separated from more conventional types of amnesia that are produced by disruption of the so called Papez circuit or the Delay-Brion memory system.

Usefulness of heavily T(2) weighted magnetic resonance images for the differential diagnosis of parotid tumours.

OBJECTIVES: To evaluate the usefulness of heavily T(2) weighted (T2W) magnetic resonance (MR) images for the differential diagnosis of parotid tumours. METHODS: Conventional T2W and heavily T2W images obtained from 43 patients with parotid tumours were reviewed retrospectively. Tumours were classified pathologically into three types: pleomorphic adenoma (25 cases), Warthin's tumour (7 cases) and malignant tumour (11 cases). During interpretation of each MR image, special attention was paid to the homogeneity and signal intensity displayed by the solid portions of the tumours. RESULTS: Heavily T2W images could distinguish pleomorphic adenoma from Warthin's tumour and malignant tumours based on the homogeneity and signal intensity of the solid portions, whereas conventional T2W images could not. On conventional T2W images, neither homogeneity nor signal intensity differed significantly among these three tumour types. On heavily T2W images, malignant and Warthin's tumours appeared more homogeneous than pleomorphic adenoma (P<0.0061); signal intensity from pleomorphic adenoma was significantly different to signal intensity from malignant tumours (P<0.05) and Warthin's tumour (P<0.005). CONCLUSIONS: Heavily T2W MR images can be useful in distinguishing pleomorphic adenoma from Warthin's tumour and malignant tumours.

Brain activation during the fist-edge-palm test: a functional MRI study.

The purpose of our study is to clarify, using functional MRI, brain regions activated during the fist-edge-palm task (FEP) compared to relatively simple hand motor tasks using either the right or the left hand in right-handed normal volunteers. The FEP was introduced to detect a disorder of voluntary movement, and it is believed to be closely related to contralateral frontal lobe damage. However, this assumption still remains controversial. Ten subjects participated in this study. Hand motor tasks were as follows: (1) the FEP, in which the subjects were requested to place their hand in three different positions sequentially: a fist resting horizontally, a palm resting vertically, and a palm resting horizontally; (2) a fist-palm task (FP), in which the subjects were asked to clench and unclench their fist alternately; and (3) a control task requiring the subjects to knock lightly with their clenched fist. The contralateral sensomotor and premotor areas were activated in the FP with the right hand and the contralateral sensorimotor, premotor, and supplementary motor areas (SMA) were activated in the FP with the left hand. In the FEP with either hand, bilateral premotor and left parietal areas and ipsilateral cerebellum were also activated as well as contralateral sensorimotor area and SMA. Our results suggest that successful performance of the FEP requires the participation of more brain areas than FP, which may explain why some patients without frontal lobe damage failed to perform the FEP.

Colour-coded fractional anisotropy images: differential visualisation of white-matter tracts--preliminary experience.

Diffusion-tensor analysis allows quantitative assessment of diffusion anisotropy. Fractional anisotropy (FA) is commonly used to quantify anisotropy. One of the limitations of FA imaging is, however, that it does not contain information about the directionality of anisotropy and it is therefore difficult to identify white-matter tracts on FA images. Our purpose was to describe a simple method of making composite images containing information about both magnitude and direction of diffusion anisotropy. The composite colour-coded FA images enabled us to identify different adjacent fibre bundles of similar degrees of diffusion anisotropy, and might be helpful in assessment of these fasciculi.

Evaluation of pulse sequences used for magnetic resonance sialography.

OBJECTIVES: To determine the most appropriate sequences for the visualization of small parotid ducts in MR sialography. METHODS: MR images of a phantom consisting of distilled water in polyethylene tubes were obtained with turbo-spin echo (TSE), single-shot turbo-spin echo (SSTSE), half-fourier acquisition, single-shot turbo-spin echo (HASTE) and turbo gradient-spin echo (TGSE) pulse sequences and compared visually and quantitatively. MR sialograms obtained from healthy volunteers and patients with Sjögren's syndrome (SS) were obtained using the same four sequences. RESULTS: In the phantom, TSE images were best and the contrast-noise ratio (CNR) highest. In the volunteers, the main ducts were especially clearly visualized with TSE and in SSTSE; however, the majority of secondary and/or tertiary parotid ducts were not depicted by any of the sequences used. In SS patients, images of small main ducts and small pseudocysts were clearer using TSE. However, TSE could not depict the narrow main ducts or peripheral ducts or very small pseudocysts. CONCLUSIONS: TSE is considered the most suitable MR sequence for assessing small parotid gland ducts. However, further improvement is needed since it does not always visualize them sufficiently.

Incremental doses of intracoronary adenosine for the assessment of coronary velocity reserve for clinical decision making.

Achievement of maximal vasodilatation of the coronary microcirculation is a prerequisite for the measurement of coronary flow reserve (CFR). The present study was designed to address the hypothesis that intracoronary adenosine yields more complete vasodilation of the coronary microcirculation when incremental doses are used, resulting in higher and more accurate coronary flow reserve measurements. Four hundred and fifty-seven patients were divided in two groups; group I (319 patients) comprised patients without angiographic evidence of significant coronary artery disease, while group II (138 patients) comprised patients with intermediate coronary stenoses (between 40% and 70% diameter stenosis). Coronary velocity reserve (CVR, a surrogate measurement for CFR) was measured during cardiac catheterization using a Doppler-tipped guidewire. Incremental doses of intracoronary adenosine (12 to 54 microg for the left coronary artery and 6 to 42 microg for the right coronary artery) were administered. There was a significant difference between the initial dose of adenosine and the subsequent incremental doses. Of a total of 479 observations, only 192 (40%) had the maximal CVR value at the first dose. Thirty-nine percent of the patients in group I and 27% in group II with an initial CVR value < 2.5 increased CVR to > or = 2.5 with incremental doses of adenosine. This study suggests that incremental doses of adenosine should be used to achieve maximal CVR for the assessment of the functional significance of coronary lesions. Cathet Cardiovasc Intervent 2001;54:34-40.

Pathophysiology, diagnosis, and current management strategies for chest pain in patients with normal findings on angiography.

Chest pain syndromes in patients with normal angiographic findings represent a multifactorial pathophysiologic state, which may range from abnormalities in pain perception to abnormalities in endothelial- and non-endothelial-dependent coronary flow reserve associated with myocardial ischemia. Treatment begins with an accurate diagnosis by obtaining a comprehensive history and performing a physical examination, followed possibly by performing functional angiography in those who continue to have symptoms. This approach may help to determine appropriate treatment.