MRI of the cervical spine with neck extension: is it useful?

Objectives

Standard MRI of the cervical spine is performed in a different anatomical position to that utilised for traditional contrast myelography. Those well practised in myelography are familiar with the considerable changes in configuration of the bony and soft tissues of the cervical spine that may occur with changes in the degree of neck flexion and extension. We set out to compare the findings in a select group of patients with myeloradiculopathy who had undergone myelography and MRI in both standard and neck-extended positions. These findings were correlated with the clinical status.

Methods

29 patients underwent myelography with CT (CTM) and MRI in neutral and neck-extended positions. The imaging was assessed for the degree of cord compression and neural foraminal narrowing, quantified using a simple grading scheme suitable for routine clinical practice. The degree of neck extension was assessed using an angular measurement.

Results

For both CTM and MRI, scanning with the neck extended significantly increases the severity of cord compression compared with the standard supine position, to a degree similar to that shown during conventional prone myelography. The degree of perceived cord compression is related to the degree of neck extension achieved. Correlation of standard MRI findings and the clinical level of radiculopathy is poor. This correlation improves when the neck is extended.

Conclusions

The most appropriate position for routine MRI of the cervical spine in degenerative disease remains unknown, but in selected patients imaging with the neck extended may provide important additional information.With the introduction of spinal surface coil technology and gradient echo sequences in the late 1980s, MRI rapidly replaced intrathecal contrast myelography as the standard imaging method for assessment of the cervical spinal cord and nerve roots. The two investigations are performed in very different anatomical positions. Standard cervical spine MRI is performed in a coil that is designed to make the patient comfortable, to minimise movement-related artefacts. This generally results in a position of mild extension of the neck. On the other hand, the majority of images for plain cervical myelography are obtained with the patient prone and the neck hyperextended so as to retain myelographic contrast within the cervical lordosis. CT myelography (CTM) is typically performed with the patient supine and with the neck straight or mildly flexed; however, CT myelography can also be performed in the prone position with the neck extended [1].For a number of years we continued to use plain myelography, with CTM as a second-line investigation in patients with cervical myelopathy and/or radiculopathy, when the results of standard MRI were inconsistent with symptoms and signs. More recently we have also performed MRI with neck extension, predominantly in patients with myelopathic features but inconclusive supine MRI. We have been unsure how extended MRI compares with myelography and whether it is able to produce the same degree of extension as myelography. We have performed CT in the prone extended position as well, but have also been unsure how that relates to standard supine CT imaging or to extended MRI. We therefore wished to compare these various modalities in a heterogeneous group of clinically problematic patients.     

Fungal versus bacterial brain abscesses: is diffusion-weighted MR imaging a useful tool in the differential diagnosis?

Introduction The aim of this study was to investigate the appearance of fungal brain abscesses on diffusion-weighted (DW) images, and to evaluate whether the imaging characteristics and apparent diffusion coefficient (ADC) values associated with fungal abscesses were distinct from those of bacterial abscesses. Methods We retrospectively reviewed the MR images from nine patients with fungal brain infections, and 17 patients with pyogenic brain abscesses. All patients underwent conventional MR sequences and DW imaging on 1.5-T clinical MR scanners. ADC values of 20 fungal and 20 bacterial brain abscesses were calculated and compared using a random factor analysis of variance. Results Multiple lesions were present in 6 of 9 patients (67%) with fungal abscesses and in 5 of 17 patients (29%) with bacterial abscesses. On DW images, all but one bacterial brain abscess showed a homogeneous high signal, whereas the appearance of fungal abscesses on DW images was more variable: in five of nine patients with fungal abscesses, the lesions were homogeneously hyperintense, while in the remaining four patients, the lesions were of mixed signal intensity. Mean ADC values were 0.74 × 10⁻³ mm²/s in the fungal group and 0.486 × 10⁻³ mm²/s in the bacterial group (P≤0.05). Conclusion Our results indicate that there is a trend towards higher ADC values in fungal lesions. Additional findings that support fungal rather than bacterial cerebral infection are multiplicity, signal heterogeneity on T2-weighted and DW imaging, and involvement of deep grey-matter nuclei.     

MRI in staging advanced gastric cancer: is it useful compared with spiral CT?

PURPOSE: During the last decade, rapid progress has been made in MR technology. Our objective was to evaluate the role of MRI in staging advanced gastric cancer (AGC; gastric cancer invading the muscularis propria) and to compare it with that of spiral CT. METHOD: We prospectively performed both MR and CT examinations on 26 patients with AGC proven by endoscopic biopsy. Contrast-enhanced CT and nonenhanced MRI with a 1.0 T scanner using FLASH, HASTE, and true-FISP sequences were obtained in each patient after injection of antiperistaltic drug and ingestion of 1 L of tap water. Fifty-two sets of CT and MR images were analyzed by two radiologists in consensus without any information from other images. T and N staging of AGC was determined according to the TNM classification. All patients underwent surgery within 1 week after both examinations. Diagnostic accuracy of each staging of AGC on CT or MRI was evaluated by comparison with the pathologic results. RESULTS: MRI was slightly superior to CT in T staging (81 vs. 73%, respectively; p < 0.05). Although MRI had a tendency to overstage the pathologic T2 cancer, positive predictability of T2 stage and sensitivity of T3 stage were high (100%, respectively). Regarding the N staging, CT was slightly superior to MRI (73 vs. 65%; p > 0.05). However, both CT and MRI demonstrated the tendency of understaging in N staging. CONCLUSION: Although MRI was superior to spiral CT in T staging, MRI cannot completely replace spiral CT in staging AGC because of its limitation in N staging.     

Pulmonary embolism: is scintigraphy useful after initial angio-CT?

PURPOSE: To assess the value of ventilation-perfusion scintigraphy after an initial helical CT with absence of pulmonary embolism (PE). MATERIAL: and methods. Twenty eight consecutive patients with clinical suspicion of pulmonary embolism underwent helical CT scan to look for an intra-luminal clot. When the CT-scan was positive for PE, diagnosis was retained. If the result was negative, a ventilation-perfusion scintigraphy was performed. If the result was also negative, diagnosis of PE was excluded. In case of discrepancy, a pulmonary angiography was performed and used as gold-standard. RESULTS: Twenty-one patients showed PE at CT-angio and 7 did not. Two of these 7 had normal or low probability scintigraphy, excluding diagnosis of PE. One had intermediate V/P scan and 4 had high probability V/P scan. For these 5 discrepancies, none of them had PE on angiography. CONCLUSION: In this population, scintigraphy was not appropriate after a negative CT-angio for PE. In case of persistent doubt after a normal initial helical CT, pulmonary angiography is required     

Pancreatic neoplasms: how useful is evaluation with US?

The usefulness of ultrasonography (US) in the evaluation of pancreatic neoplasms was assessed in 51 patients. Indications for US included jaundice (n = 19), pain (n = 16), weight loss and anorexia (n = 4), clinically palpable mass (n = 3), bleeding in the upper gastrointestinal tract (n = 1), and gastric outlet obstruction (n = 1). Three patients were investigated because of a previous abnormal US examination; in four the mass was an incidental observation. Sonograms were interpreted without knowledge of results from other procedures. Pancreatic masses were detected in 50 patients. Biliary and pancreatic duct obstructions were seen in 29 and 27 patients, respectively. Liver metastases were identified in 16 patients and missed in three that were not detected with either US or computed tomography. Vascular involvement was predicted in 12 patients and missed in four, while lymphadenopathy was seen in 16 and missed in five. Thirty-one cases of unresectable disease were correctly predicted with US. Resectability was not as accurately determined; only seven of 19 "resectable" lesions were successfully removed. US is an effective tool in the detection and preoperative evaluation of pancreatic malignancy.     

Is diffusion-weighted imaging useful in grading and differentiating histopathological subtypes of meningiomas?

Purpose

Meningiomas are mostly benign, however atypical or malignant subtypes with more aggressive clinical course and higher recurrence rates can also be seen. The purpose of this study was to determine whether histopathological subtypes of meningiomas could be assessed preoperatively using apparent diffusion coefficient (ADC) values.

Materials and methods

Conventional magnetic resonance (MR) and diffusion-weighted (DW) imaging of 177 adult patients with pathologically proven meningiomas were retrospectively evaluated. Tumor size and the degree of associated edema were noted. The signal intensity of the lesions on DW imaging was evaluated and graded. Mean ADC values were obtained as the mean of measurements from three regions of interests within the mass. ADC ratios of meningioma/contralateral normal appearing subcortical parietal white matter were also calculated.

Results

The histopathological analysis revealed 135 benign, 37 atypical and 5 malignant lesions. With classification according to the subtype, the mean ADC values and ratios of benign meningiomas were as 0.99 ± 0.12 × 10⁻³ mm²/s and 1.22 ± 0.07, respectively. ADC values for atypical and malignant groups were both 0.84 ± 0.1 × 10⁻³ mm²/s. The ADC ratios were 1.05 ± 0.1 and 0.96 ± 0.2 for atypical and malignant subtypes, respectively. There was no statistically significant difference between the mean ADC ratios of the three subtypes (ANOVA test; P ≥ 0.05). Gender, age of the patients and tumor size showed no statistically significant difference between the different histological groups.

Conclusion

DW MR imaging was not found to have any additional value in determining histological behaviour nor in differentiating histopathological subtypes of meningiomas.     

Endocrine pancreatic tumours: which are the most useful MRI sequences?

Objectives  

To determine magnetic resonance imaging (MRI) signal and enhancement characteristics of endocrine pancreatic tumours (ETPs) and which MR sequences show them most consistently.     

Inguinoscrotal bladder herniation: is CT a useful tool in diagnosis?

Urinary bladder herniation into the inguinal canal is a rare occurrence. The condition is often diagnosed during inguinal hernia surgery. We present a rare case of inguinoscrotal bladder herniation with its computed tomography findings.     

SSH-EPI diffusion-weighted MR imaging of the spine with low b values: is it useful in differentiating malignant metastatic tumor infiltration from benign fracture edema?

Objective  Conventional MR sequences are sometimes not helpful in differentiating benign from pathologic fractures. Our aim was to evaluate the usefulness of single-shot echo-planar imaging sequences (diffusion-weighted imaging (DWI)/SSH-EPI) with low b value in differentiating malignant metastatic tumor infiltration of vertebral bone marrow from benign vertebral fracture edema. Materials and methods  A total of 47 patients, 20 with benign fractures and 27 with tumor infiltration, were included in this prospective study. Diffusion-weighted MR images were obtained by single-shot echo-planar imaging technique with diffusion gradient (b = 300 s/mm²; TR/TE, 1,400/100), using a 1.5 T MR scanner. T1- and T2-weighted images and short inversion time inversion-recovery images were available for all 64 lesions. The lesions on DWI/SSH-EPI were categorized as having hypo-, iso-, or hyperintense signal intensity relative to normal vertebrae by two experienced radiologists. Results  We evaluated signal intensity patterns on DWI/SSH-EPI in 64 lesions, which showed low signal intensity on T1-weighted images in both benign fractures and metastasis. With the exception of sclerotic metastases in two patients, malignant metastatic tumor infiltration was hyperintense with respect to normal bone marrow on diffusion-weighted images; all but four benign vertebral fractures were isointense with respect to normal bone marrow. Conclusion  Single-shot echo-planar imaging sequences (DWI/SSH-EPI) with low b value provided excellent distinction between metastatic tumor infiltration and benign vertebral fracture edema. Hyperintense signal intensity on DWI/SSH-EPI was highly specific for the diagnosis of metastatic tumor infiltration of the spine.     

MR arthrography of postoperative knee: for which patients is it useful?

PURPOSE: To assess which postoperative patients benefit most from MR arthrography of the knee. MATERIALS AND METHODS: One hundred consecutive MR arthrograms obtained in patients who had previous knee surgery underwent retrospective review in consensus by three radiologists after prospective reading by one of the three radiologists. Criterion on MR arthrograms for a retear was abnormal tracking of an intraarticular dilute gadolinium-based contrast material and saline mixture into the substance of a meniscus. Patients were separated into three groups: those with more than 25% meniscal resection, those with less than 25% meniscal resection, and those with meniscal repair. All 100 patients had preoperative MR images to review directly in conjunction with the postoperative MR images. Fifty-seven of these 100 patients underwent second-look arthroscopy. RESULTS: Nine patients had MR findings consistent with avascular necrosis. Nineteen patients had marked degenerative arthrosis in the area of previous surgery. Seven patients had chondral defects or injuries. Twenty-nine patients had clear MR evidence of a meniscal retear without any contrast material injected into the joint. In 32 of the 100 patients, intraarticular contrast material was useful in demonstrating a retear. Of these 32 patients, 22 had MR arthrographic evidence of a retear, while 10 had no clear MR arthrographic finding to explain postoperative pain. Four additional patients had no clear MR imaging or MR arthrographic abnormality. All patients with meniscal repair (n = 16) needed MR arthrography to diagnose a residual or recurrent meniscal tear. No patient with less than 25% meniscal resection (n = 23) needed MR arthrography to demonstrate a residual or recurrent meniscal tear. Sixteen of 61 patients with more than 25% meniscal resection needed MR arthrography to demonstrate a residual or recurrent meniscal tear. CONCLUSION: All patients with meniscal repair required MR arthrography. All patients with meniscal resection of more than 25%, who did not have severe degenerative arthrosis, chondral injuries, or avascular necrosis required MR arthrography. Patients with less than 25% meniscal resection did not need MR arthrography.     

Do acute lesions of Wernicke's encephalopathy show contrast enhancement? Report of three cases and review of the literature

Contrast medium was given intravenously to three nonalcoholic patients who underwent MRI or CT in the acute stage of Wernicke's encephalopathy. Pathological enhancement was not seen in one patient examined within 4 days of clinical onset, was mild in a another 3 days after clinical deterioration and marked in a patient examined 12 days after admission. Contrast enhancement of lesions was present in half of 12 cases of acute disease reported previously. There was a substantial overlap in the time interval between clinical onset and contrast-enhanced CT or MRI in the groups of enhancing and nonenhancing lesions. Since contrast enhancement may be absent in acute WE, proton-density and T 2-weighted images are more useful for diagnosis of this reversible but potentially fatal condition. Received: 18 December 1997 Accepted: 15 July 1998