Magnetic resonance imaging findings in chronic carbon monoxide intoxication

Purpose: To define the cranial magnetic resonance imaging (MRI) features of the chronic stage of carbon monoxide (CO) poisoning in patients with and without neuropsychiatric sequelae.

Material and Methods: Eight patients who had neither symptoms nor neurological sequelae and eight patients with neuropsychiatric sequelae were included in the study. Patients aged between 9 to 57 (mean 32.2 years). All patients had been comatose at initial admittance and awoke after normobaric 100% oxygen therapy within 1-7 days. In this study, the patients were being examined with routine cranial MRI between 1 and 10 years (mean 3.4 years) after exposure to CO.

Results: The most common finding was bilateral symmetric hyperintensity of the white matter, which was more significant in the centrum semiovale, with relative sparing of the temporal lobes and anterior parts of the frontal lobes on T2-weighted and FLAIR images in all patients. Cerebral cortical atrophy was seen in 10 patients; mild atrophy of cerebellar hemispheres in 8; and vermian atrophy in 11. Corpus callosum was atrophic in one patient. Bilateral globus pallidus lesions were seen in three patients. The lesions were hypointense on T1-weighted images and hyperintense on T2-weighted and FLAIR images.

Conclusion: Patients with severe CO intoxication may develop persistent cerebral changes independently of their neuropsychiatric findings in the chronic stage. They may present with characteristic MRI findings as described here, even if asymptomatic. The history of CO exposure is therefore helpful for recognizing and interpreting the MRI findings of chronic stage CO intoxication.     

Magnetic resonance imaging in suspected rectal cancer: determining tumor localization, stage, and sphincter-saving resectability at 3-Tesla-sustained high resolution

Purpose: To assess image quality and overall accuracy of 3-Tesla (3T)-sustained high-resolution magnetic resonance (MR) imaging for diagnostic preoperative workup in suspected rectal carcinoma.

Material and Methods: Twenty-three patients with suspected rectal cancer underwent unenhanced and contrast-enhanced fat-suppressed pelvic high-resolution MR imaging using a four-channel phased-array pelvic coil at 3T. Image quality, tumor stage, distance from the anorectal margin, and sphincter-saving resectability were prospectively assessed by two blinded readers. The results were correlated with clinical, surgical, and histopathologic findings.

Results: In all 23 patients, MR images were of diagnostic quality, and malignancy was correctly identified in 21 patients. The accuracy for determining sphincter-saving resectability was 100% (19/19). T stage and N stage were correctly diagnosed in 95% and 91%, respectively. MRI allowed correct identification of tumor extension and its relation to surgically relevant pelvic structures including the anorectal margin and mesorectal fascia. Transverse T2-weighted fast spin-echo images compared superiorly to all other sequences for the diagnosis of mesorectal infiltration and lymph node involvement. Moreover, transverse fat-suppressed contrast-enhanced T1-weighted images were valuable for identifying tumor infiltration, while sagittal sections were useful for the detection of longitudinal tumor extension.

Conclusion: MR imaging with phased-array receiver coils at 3T facilitated both visualization of different pathologic conditions of the rectum and accurate determination of tumor stage in rectal carcinomas. Thus, this noninvasive diagnostic approach appeared highly suitable for the assessment of patients with suspected rectal carcinoma.     

Diffusion-weighted magnetic resonance imaging and magnetic resonance spectroscopy in the evaluation of focal cerebral tubercular lesions

Purpose: To review magnetic resonance (MR) diffusion-weighted imaging (DWI) and spectroscopy findings in patients with focal cerebral tuberculosis and to assess whether these techniques can adequately characterize focal cerebral tubercular lesions.

Material and Methods: Sixteen patients with single or multiple lesions were evaluated on a 1.5T MR system. DWI was performed with three 'b' values of 50, 500, and 1000 s/mm² and the apparent diffusion coefficient maps were calculated. MR spectroscopy was performed using the point-resolved single-voxel technique with 2 echo time values of 135 ms and 270 ms. The signal intensities of the tubercular lesions on diffusion images and the apparent diffusion coefficients (ADCs) of their centers, along with MR spectroscopy findings, were analyzed in relation to their T2-weighted MR appearances.

Results: DWI identified 17 of the 20 lesions evaluated. Increased signal intensity was seen in 9 of the 17 lesions. The ADCs of the lesions ranged from 0.406 to 2.64×10^-3 mm²/s (mean±SD: 1.038±0.609 mm²/s). Most of the lesions with hyperintense centers on T2-weighted images were of increased intensity on diffusion images, while those with hypointense centers on T2-weighted images were of decreased signal intensity on diffusion images. However, no statistical difference in the ADCs was found between lesions with increased and those with decreased signal intensity centers on T2-weighted images. MR spectroscopy revealed a lipid peak at 0.9-1.3 ppm in all of the 14 lesions evaluated. An increase in normalized choline:creatine ratio was found in all the lesions in which the spectra were obtained with the voxel, including a variable portion of the lesion wall.

Conclusion: DWI and MR spectroscopy help in determining the nature of cerebral tubercular lesions; however, since the findings are varied, they do not help in specific characterization.     

Comparative study of fluorodeoxyglucose positron emission tomography and magnetic resonance imaging for the detection of spinal bone marrow infiltration in untreated patients with multiple myeloma

Background: The presence and extent of osteolytic bone lesions in untreated patients with multiple myeloma are important factors in the staging of the disease, and the extent of bone lesions in multiple myeloma cases significantly influences decisions regarding therapy. Recently, fluorodeoxyglucose positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) have been used to detect bone marrow involvement in patients with multiple myeloma.

Purpose: To compare the efficacy of FDG-PET and MRI for the detection of bone marrow infiltration into the spine in untreated patients with multiple myeloma.

Material and Methods: Twenty-two patients with multiple myeloma underwent both FDG-PET and spine MRI. The examined spinal regions by MRI included 21 thoracic and lumbar spines, one lumbar spine, and 12 cervical spines. The following imaging sequences were performed: T1-weighted spin-echo MRI with and without fat suppression, and T2-weighted spin-echo MRI in the sagittal plane. In the patients with bone marrow abnormalities, an additional contrast-enhanced T1-weighted spin-echo MR image and a fat-suppressed T1-weighted spin-echo MR image were obtained. Patients were divided into three groups on the basis of the criteria defined by Durie and Salmon: stage I (n=9), stage II (n=3), and stage III (n=10). The number and location of lesions detected in both FGD-PET and MRI were recorded, and the lesions were compared using the McNemar test. Bone marrow biopsy results, the patient's clinical examinations, and other imaging findings (MRI, FDG-PET, etc.) were used as references.

Results: In stages I and II (37 lesions in 12 patients), FDG-PET and MRI detected lesions in 78% (29 of 37 lesions) and 86% (32 of 37 lesions), respectively. However, the difference between the abilities of FDG-PET and MRI to detect lesions was not statistically significant (P=0.317). In stage III (101 lesions in 10 patients), FDG-PET and MRI detected lesions in 80% (81 of 101 lesions) and 92% (93 of 101 lesions), respectively. The difference between the abilities of FDG-PET and MRI to detect lesions was statistically significant (P=0.038).

Conclusion: MRI is superior to FDG-PET in detecting bone marrow involvement in the spine of patients with advanced multiple myeloma.     

Intraarterial infusion chemotherapy and conformal radiotherapy for cancer of the mouth: prediction of the histological response to therapy with magnetic resonance imaging

Background: Although intraarterial chemotherapy has been used to treat head and neck cancers, some cases have shown poor response. If we can predict the response to this therapy on MRI, individual treatment plans may be altered to the most appropriate form of treatment.

Purpose: To evaluate whether MRI can predict the histological response to preoperative chemoirradiation in patients with cancer of the mouth.

Material and Methods: This study comprised of 29 consecutive patients with 30 oral cancers. All patients underwent tumor resection after intraarterial infusion chemotherapy and conformal radiotherapy. We compared the margin of the tumor, the presence of bone invasion, tumor area, and volume on pre- and post-treatment MRI with histological responses.

Results: Eighteen lesions showed an excellent response, nine exhibited a good response, and three a poor response. Only the tumor area on pretreatment T1-weighted images and the tumor area and volume on pretreatment enhanced T1-weighted images were significantly correlated with the histological response (P = 0.039, 0.008, and 0.016, respectively); smaller cancers showed better responses. The other factors were not significantly correlated with the histological responses.

Conclusion: MRI parameters, excluding initial tumor area and volume, were not predictive of the histological response of oral tumors to preoperative treatment.     

High-resolution T2-weighted abdominal magnetic resonance imaging using respiratory triggering: impact of butylscopolamine on image quality

Background: Respiratory triggering allows the acquisition of high-resolution magnetic resonance (MR) images of the upper abdomen. However, the depiction of organs close to the gastrointestinal tract can be considerably impaired by ghosting artifacts and blurring caused by bowel peristalsis.

Purpose: To evaluate the effect of gastrointestinal motion suppression by intramuscular butylscopolamine administration on the image quality of a respiratory-triggered T2-weighted turbo spin-echo (T2w TSE) sequence of the upper abdomen.

Material and Methods: Images of 46 patients were retrospectively analyzed. Twenty-four patients had received intramuscular injection of 40 mg butylscopolamine immediately before MR imaging. Fourteen of the 24 patients in the butylscopolamine group underwent repeat imaging after a mean of 29 min. Quantitative analysis of the ghosting artifacts was done by measuring signal intensities in regions of interest placed in air anterior to the patient. In addition, image quality was assessed qualitatively by two radiologists by consensus.

Results: Spasmolytic medication with butylscopolamine reduced ghosting artifacts and significantly improved image quality of the respiratory-triggered T2w TSE sequence. The most pronounced effect of butylscopolamine administration on image quality was found for the pancreas and the left hepatic lobe. The rate of examinations with excellent or good depiction of the pancreas and the left hepatic lobe in the group without premedication and in the butylscopolamine group was 55% vs. 96% (pancreatic head), 35% vs. 88% (pancreatic body), 43% vs. 96% (pancreatic tail), and 45% vs. 83% (left hepatic lobe), respectively. Regarding the duration of the effect of intramuscular butylscopolamine, repeat imaging after a mean of 29 min did not result in a significant deterioration of image quality.

Conclusion: Intramuscular butylscopolamine administration significantly improves image quality of respiratory-triggered T2-weighted abdominal MR imaging by persistent reduction of peristaltic artifacts. MR imaging of the liver and pancreas in particular benefits from the suppression of gastrointestinal peristalsis by butylscopolamine.     

Retropharyngeal tendinitis: radiographic and magnetic resonance imaging findings

Purpose: To describe the magnetic resonance imaging (MRI) findings in retropharyngeal tendinitis.

Material and methods: Within 1 year, four patients presenting with symptoms of retropharyngeal tendinitis were examined by radiography and MRI.

Results: On MRI and radiographs, all patients had characteristic soft-tissue swellings and calcifications related to the tendon of the longus colli muscle situated inferior to the anterior arc of C1. MRI showed well-defined edema, with high signal in the retropharyngeal tissue anterior to C1-C5 on short T1 inversion recovery (STIR) sequences, low signal on T1-weighted sequences, and low signal in the calcification on both sequences. In addition, three patients had high signal intensity changes on STIR sequences in the atlantoaxial joint situated posterior to the anterior arc of C1.

Conclusion: MRI is a sensitive and accurate method in the diagnosis of retropharyngeal tendinitis. A new finding in this condition is an effusion or synovitis in the anterior atlantoaxial joint. MRI is a valuable tool in differentiating retropharyngeal tendinitis from other diagnoses such as retropharyngeal abscess, pyogenic spondylitis, and spondyloarthropathy.     

Imaging findings in symptomatic patients with femoral diaphyseal stress injuries

Purpose: To assess the imaging findings seen in symptomatic patients with stress injuries of the femoral diaphysis.

Material and Methods: Seven patients (5 F, 2 M, age range 16 to 56 years, mean 38 years) underwent imaging evaluation of the symptomatic lower extremity due to an insidious onset of thigh or groin pain unrelated to trauma. Imaging studies included radiography and magnetic resonance imaging (MRI) in seven patients, bone scintigraphy in five, and computed tomography (CT) in three.

Results: Radiographs depicted three frank fractures in two patients, and revealed findings of stress injury in six patients. Available scintigraphic and CT findings were abnormal. On MR images, a solitary fracture was seen in two patients; two patients presented with bilateral stress fractures of the femoral diaphysis; and all seven patients had the imaging features of stress injury. Femoral diaphyseal stress fractures (n = 6) appeared as linear regions of T1- and T2-weighted low signal intensity, surrounded by diffuse bone marrow edema. Three of the six frank fractures, with an evident fracture line, were longitudinal and parallel to the cortical surface.

Conclusion: Femoral diaphyseal stress fractures are often inconspicuous with conventional radiography. MRI depicts the changes of stress injury in the femoral diaphysis, and is particularly useful in documenting the presence, morphology, and extent of fracture(s), information valuable for definitive diagnosis and appropriate management.     

Hepatocellular carcinoma in association with hepatic focal nodular hyperplasia

Purpose: To report the association between hepatocellular carcinoma (HCC) and hepatic focal nodular hyperplasia (FNH) and the possible impact on clinical decision-making with regard to resective approaches in patients with FNH.

Material and Methods: We retrospectively analyzed the findings in 77 adult patients who underwent liver resections for FNH between October 1989 and September 2001 at our center. HCC within the confines of FNH was found in two patients. We demonstrate the magnetic resonance imaging (MRI) and macroscopic and microscopic findings.

Results: Presurgical MRI demonstrated heterogeneous signal characteristics of moderately hyperintense FNH on T2-weighted images and, after IV administration of super-paramagnetic iron oxide particles, HCC in FNH was barely delineable. Both patients underwent successful right hemihepatectomy to remove the suspicious FNH with diameters of 12 and 14 cm; intralesional HCC diameters were 3 and 5 cm, respectively. Patients could be rapidly dismissed. However, one patient died after recurrence of HCC 1.5 years after surgery, whereas the other patient continues tumor-free 4 years after surgery. Alpha-feto-protein was normal in both patients.

Conclusion: In FNH with rapid growth tendency and heterogenic MR appearance, surgical removal should be considered to overcome the risk of inadequate therapy in the very rare group of patients with HCC in association with FNH.     

Granulomatous mastitis: radiological findings

Purpose: To evaluate the radiological, ultrasonographic, and magnetic resonance imaging (MRI) findings of idiopathic granulomatous mastitis.

Material and Methods: Between April 2002 and June 2005, the mammography, ultrasound, color Doppler ultrasound, nonenhanced MR, and dynamic MR findings of nine patients with the preliminary clinical diagnosis of malignancy and the final diagnosis of granulomatous mastitis were evaluated.

Results: On mammography, asymmetrical focal densities with no distinct margins, ill-defined masses with spiculated contours, and bilateral multiple ill-defined nodules were seen. On ultrasound, in four patients a discrete, heterogenous hypoechoic mass, in two patients multiple abscesses, in one patient bilateral multiple central hypo peripheral hyperechoic lesions, in two patients heterogeneous hypo- and hyperechoic areas together with parenchymal distortion, and in one patient irregular hypoechoic masses with tubular extensions and abscess cavities were seen. Five of the lesions were vascular on color Doppler ultrasound. On MR mammography, the most frequent finding was focal or diffuse asymmetrical signal intensity changes that were hypointense on T1W images and hyperintense on T2W images, without significant mass effect. Nodular lesions were also seen. On dynamic contrast-enhanced mammography, mass-like enhancement, ring-like enhancement, and nodular enhancement were seen. The time-intensity curves differed from patient to patient and from lesion to lesion.

Conclusion: The imaging findings of idiopathic granulomatous mastitis have a wide spectrum, and they are inconclusive for differentiating malignant and benign lesions.     

Alveolar echinococcosis of the liver: correlative color Doppler US, CT, and MRI study

Purpose: To determine and compare the imaging features of hepatic alveolar Echinococcosis using color Doppler US, CT, and MRI.

Material and Methods: Abdominal CT and MRI with and without contrast agents and color Doppler US were performed on seven patients with hepatic alveolar Echinococcosis. The lesions were evaluated for location, features of echogenicity, intensity and density, calcification, and vascular, hilar, and perihepatic involvement. The diagnosis was confirmed histopathologically in all patients.

Results: Six patients had solitary lesions, and one displayed multiple lesions. The lesions were generally seen as heterogeneous and hyper- or hypoechoic when imaged with color Doppler US, hypodense with CT, and hypointense with MRI, in comparison with the liver parenchyma. Calcification, central necrosis, and small peripheral cysts were observed in six, seven, and four patients, respectively. Vascular flow or contrast enhancement was not observed in any of the cases. A look at the respective advantages of each method reveals that calcification was best rendered visible via CT, small peripheral cysts with T2-weighted MRI, central necrosis with CT and MRI, and perihepatic invasion with multiplanar MRI. Vascular involvement was revealed by all methods.

Conclusion: Color Doppler US, CT, and MR imaging function extremely well as complementary methods in the diagnosis of HAE. Color Doppler US should be performed in these patients owing to its ability to efficiently detect the disease. Knowledge of imaging characteristics makes it possible to radiologically ascertain an early diagnosis.     

Wallenberg's lateral medullary syndrome: diffusion-weighted imaging findings

Purpose: To investigate the efficacy of diffusion-weighted imaging in patients with Wallenberg's lateral medullary syndrome.

Material and Methods: Thirteen patients with Wallenberg's lateral medullary syndrome were examined with conventional and echoplanar diffusion-weighted magnetic resonance (MR) imaging in a 1.5 T magnetic resonance unit. MR examinations were obtained in the acute or subacute stage of clinical syndrome, and diffusion-weighted imaging (DWI) was considered to be positive for infarction when an increase in signal was seen on b=1000 s/mm² images in the posterolateral medullary localization.

Results: DWIs were positive in 12 patients in the acute or subacute stages of this clinical syndrome. A false-negative result was obtained in only one patient examined within the first day, 10 h after onset of the symptoms. In the visual evaluation of the DWI, the contrast between normal and infarcted brainstem area was better in the high b-value images than in the apparent diffusion coefficient map images.

Conclusion: DWI is a valuable technique for examining patients presenting with the signs and symptoms of Wallenberg's syndrome and high b-value images can provide complementary data to T2-weighted images. However, because most of our case group were in either the acute or subacute stage, true sensitivity of the method in the hyperacute stage of the syndrome remains unclear.     

Accuracy and precision in the detection of articular cartilage lesions using magnetic resonance imaging at 1.5 Tesla in an in vitro study with orthopedic and histopathologic correlation

Background: Magnetic resonance (MR) sequences for cartilage visualization have been the target of numerous studies, and the optimal sequence for cartilage imaging remains a matter of debate in the literature.

Purpose: To compare MR findings with different MR sequences for the detection of cartilage lesions in fresh deep-frozen human cadaveric patellae in an in vitro setting.

Material and Methods: Ten cadaveric patellae were imaged on a 1.5T MR scanner with a 2×2 channel carotid sandwich coil and a conventional knee coil, and compared with orthopedic findings and gold-standard histopathology. MR sequences were: a) fat-saturated (FS) proton density-weighted (PDw) turbo spin-echo (TSE) sequence (TR/TE 4000/39 ms); b) T2-weighted (T2w) double-echo steady-state (DESS) 3D water-excitation (we) sequence (TR/TE 17/4.7 ms); c) 3D-PDw-SPACE (sampling perfection with application-optimized contrasts using different flip-angle evolutions)-we sequence (TR/TE 1800/19 ms). Accuracy, Kendall's tau-b correlation, and weighted kappa coefficients were calculated.

Results: Accuracy for cartilage lesion detection with the FS PDw-TSE sequence and the carotid coil was 78.3%, and with the knee coil 73.9%. For the T2wDESS-3D-we sequence, the corresponding values were 69.5% and 65.2%, and for the 3D-PDw-SPACE-we sequence 65.2% and 60.8%, respectively. Kendall's tau-b correlation ranged between 0.508 for the 3D-PDw-SPACE-we sequence (knee coil) and 0.720 for the FS PDw-TSE sequence (carotid and knee coil). Weighted kappa coefficient was lowest for the 3D-PDw-SPACE-we sequence (knee coil) at 0.607, and highest for the carotid coil and FS PDw-TSE sequence at 0.779.

Conclusion: The evaluated FS PDw-TSE sequences are superior in comparison to the T2wDESS-3D-we and 3D-PDw-SPACE-we sequences in the in vitro setting for the detection of cartilage lesions, and are comparable to results reported in the literature.     

Magnetic resonance imaging and radiographic findings of seal finger

Purpose: To describe the magnetic resonance imaging (MRI) and radiographic findings of five patients with seal finger.

Material and Methods: The MR images and radiographs of five patients with seal finger were retrospectively evaluated. MRI was performed on four patients in the subacute phase, and follow-up imaging was done on one of them at 5 months. One patient had MRI only at a later stage 5 years after onset. Radiographs were taken three times in the subacute phase and once at a later stage. One patient had had seal finger in another finger previously.

Results: Short-tau inversion-recovery (STIR) sequence showed extensive subcutaneous soft tissue edema in all four patients in the subacute phase and tenosynovitis of the flexion tendons in two cases. Three patients had edema in 2-3 phalanges, and effusion in the distal interphalangeal (DIP) joint was seen in one case. At the later stage, no signal pathology in soft tissues or bones was seen in STIR images. In the subacute phase, radiographs showed digital soft-tissue swelling in three patients, and one patient had a narrowed DIP joint, periarticular osteoporosis, and a periosteal reaction. At the later stage, flexion contracture of the finger was seen.

Conclusion: In addition to soft-tissue infection, seal finger causes bone marrow edema, tenosynovitis, and effusion in the interphalangeal joints visible as increased signal intensity in STIR images. Radiographs reveal periarticular osteoporosis with loss of cartilage in the subacute phase and flexion contracture at the later stage. MRI (STIR) allows more precise delineation of the inflammatory process compared to radiography.     

Application of turbo fluid-attenuated inversion-recovery MRI in evaluation of intraspinal tumors

PURPOSE: Although fluid-attenuated inversion-recovery (FLAIR) magnetic resonance imaging (MRI) is widely applied to diagnose central nervous system diseases, its role in diagnosis of intraspinal tumors is unclear. In this study, we evaluated the potential clinical application of a turbo FLAIR sequence for imaging of intraspinal tumors. MATERIALS AND METHODS: Forty-eight consecutive patients with intraspinal tumors underwent MRI with turbo FLAIR and turbo spinal echo (TSE) sequences. Turbo FLAIR images were then qualitatively and quantitatively compared with T2-weighted TSE images. RESULTS: Turbo FLAIR images were evaluated as superior to T2-weighted TSE images for image artifact, extradural tumor conspicuity, and intradural extramedullary tumor conspicuity and detection. Intramedullary tumor conspicuity with turbo FLAIR was less than T2-weighted TSE. Similar capabilities in detection of extradural and intramedullary tumors were found between turbo FLAIR and T2-weighted TSE. Turbo FLAIR and T2-weighted TSE displayed similar normal spinal cord signal-noise ratio (SNR) and tumor-to-cerebrospinal fluid (CSF) contrast-to-noise ratio (CNR). In addition, turbo FLAIR yielded significantly higher tumor-to-CSF contrast than T2-weighted TSE. However, tumor SNR, tumor-to-normal spinal cord contrast and CNR with turbo FLAIR images were lower than those with T2-weighted TSE images. CONCLUSION: This study demonstrated (a) a superiority of turbo FLAIR to T2-weighted TSE in displaying and detecting intradural extramedullary tumors, (b) a superiority of turbo FLAIR to T2-weighted TSE in demonstrating extradural tumors, and (c) less usefulness in displaying intramedullary tumors with turbo FLAIR than with T2-weighted TSE.     

Magnetic resonance imaging with true fast imaging with steady-state precession and half-Fourier acquisition single-shot turbo spin-echo sequences in cases of suspected placenta accreta

Purpose: To present the magnetic resonance imaging (MRI) findings of placenta accreta in suspected cases of placenta accreta with true fast imaging with steady-state precession (True FISP) and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences.

Material and Methods: Five patients underwent MRI with HASTE (n=5) and/or True FISP (n=4) sequences for suspected placenta accreta. Retrospective review of MRI was performed to define the location and extent of the implantation abnormality.

Results: The uteroplacental interface was visualized as three layers; inner low signal intensity layer, middle high signal intensity layer of myometrium, and outer low signal intensity layer of uterine serosa. Three cases were diagnosed with placenta accreta on MRI and focal non-visualization of the inner layer was demonstrated.

Conclusion: The finding of focal non-visualization of the inner layer between the placenta and myometrium by MRI with True FISP and HASTE sequences was the diagnostic finding for placenta accreta.     

Detection of cerebrospinal fluid leakage: initial experience with three-dimensional fast spin-echo magnetic resonance myelography

Background: The pathogenesis of cerebrospinal fluid (CSF) hypovolemia is supposed to be caused by CSF leakage through small dural defects.

Purpose: To compare source three-dimensional (3D) fast spin-echo (FSE) images of magnetic resonance (MR) myelography with radionuclide cisternography findings, and to evaluate the feasibility of MR myelography in the detection of CSF leakage.

Material and Methods: A total of 67 patients who were clinically suspected of CSF hypovolemia underwent indium-111 radionuclide cisternography, and 27 of those who had direct findings of CSF leakage were selected for evaluation. MR myelography with 3D FSE sequences (TR/TE 6000/203 ms) was performed at the lumbar spine for all patients. We evaluated source images and maximum intensity projection (MIP) images of MR myelography, and the findings were correlated with radionuclide cisternography findings. MR myelography of five healthy volunteers was used as a reference. The MR visibility of the CSF leakage was graded as definite (leakage clearly visible), possible (leakage poorly seen), or absent (not shown).

Results: CSF leakage was identified with source 3D FSE images in 22 (81.5%) of 27 patients. Of the 22 patients, 16 were graded as definite and six were graded as possible. For the definite cases, 3D FSE images clearly showed the extent of the leaked CSF in the paraspinal structures. In the remaining five patients with absent findings, radionuclide cisternography showed only slight radionuclide activity out of the arachnoid space.

Conclusion: Source 3D FSE images of MR myelography seem useful in the detection of CSF leakage. Invasive radionuclide cisternography may be reserved for equivocal cases only.     

Whole body magnetic resonance imaging in the diagnosis of Parsonage Turner syndrome

Purpose: To describe magnetic resonance imaging (MRI) findings in patients with suspected Parsonage Turner syndrome and to emphasize the value of an additional whole body MR scan to improve specificity of this diagnosis.

Material and Methods: Three patients with proven Parsonage Turner syndrome referred for conventional MRI of the shoulder girdle and additional whole body turboSTIR MRI were included for study.

Results: In each case, imaging revealed edema in the muscles of the shoulder girdle. Whole body turboSTIR MRI scan confirmed localized unilateral changes in each case improving specificity and confidence in the diagnosis of Parsonage Turner syndrome in each case.

Conclusion: Whole body turboSTIR MR imaging is a useful diagnostic tool in the evaluation of patients with suspected Parsonage Turner syndrome. Inclusion of the brain, neck, brachial plexus, and extremity musculature at whole body imaging allows differentiation from polymyositis and elimination of additional causes of shoulder girdle pain and weakness including gross lesions in the brain, neck, and brachial plexus by a single non-invasive study.     

Comparison of Gd-DTPA-induced signal enhancements in rat brain C6 glioma among different pulse sequences in 3-Tesla magnetic resonance imaging

Background: T1-shortening contrast media are routinely used in magnetic resonance (MR) examinations for the diagnosis of brain tumors. Although some studies show a benefit of 3 Tesla (T) compared to 1.5T in delineation of brain tumors using contrast media, it is unclear which pulse sequences are optimal.

Purpose: To compare gadopentetate dimeglumine (Gd-DTPA)-induced signal enhancements in rat brain C6 glioma in the thalamus region among different pulse sequences in 3T MR imaging.

Material and Methods: Five rats with a surgically implanted C6 glioma in their thalamus were examined. T1-weighted brain images of the five rats were acquired before and after Gd-DTPA administration (0.1 mmol/kg) using three clinically available pulse sequences (spin echo [SE], fast SE [FSE], fast spoiled gradient echo [FSPGR]) at 3T. Signal enhancement in the glioma (E_T) was calculated as the signal intensity after Gd-DTPA administration scaled by that before administration. Pulse sequences were compared using the Tukey-Kramer test.

Results: E_T was 1.12±0.05 for FSE, 1.26±0.11 for FSPGR, and 1.20±0.11 for SE. FSPGR showed significantly higher signal enhancement than FSE and comparable enhancement to SE.

Conclusion: FSPGR is superior to FSE and comparable to SE in its ability to delineate rat brain C6 glioma in the thalamus region.     

Pulmonary perfusion in acute pulmonary embolism: agreement of MRI and SPECT for lobar, segmental and subsegmental perfusion defects

Purpose: To assess prospectively the agreement of magnetic resonance (MR) pulmonary perfusion with single-photon emission computed tomography (SPECT) perfusion for perfusion defects down to the subsegmental level in patients with suspected pulmonary embolism (PE).

Material and Methods: In 41 patients with suspected PE, contrast-enhanced MR pulmonary perfusion (3D-FLASH, TR/TE 1.6/0.6 ms) was compared to SPECT perfusion on a per-examination basis as well as at the lobar, segmental, and subsegmental level.

Results: The MRI protocol was completed in all patients, and mean examination time was 3 min 56 s. MR perfusion showed a very high agreement with SPECT (kappa value per examination 0.98, and 0.98, 0.83, and 0.69 for lobar, segmental, and subsegmental perfusion defects, respectively). Of 15 patients with PE, MR perfusion detected 14 cases.

Conclusion: The very high agreement of MR perfusion with SPECT perfusion enables the detection of subtle findings in suspected PE.