T1-weighted Fast Low-angle Shot Research Articles

Dynamic gadolinium-enhanced magnetic resonance imaging allows accurate assessment of the synovial inflammatory activity in rheumatoid arthritis knee joints: a comparison with synovial histology

Objective: To determine whether dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) evaluated using semi-automatic image processing software can accurately assess synovial inflammation in rheumatoid arthritis (RA) knee joints.Methods: In 17 RA patients undergoing knee surgery, the average grade of histological synovial inflammation was determined from four biopsies obtained during surgery. A preoperative series of T1-weighted dynamic fast low-angle shot (FLASH) MR images was obtained. Parameters characterizing contrast uptake dynamics, including the initial rate of enhancement (IRE), were generated by the software in three different areas: (I) the entire slice (Whole slice); (II) a manually outlined region of interest (ROI) drawn quickly around the joint, omitting large artefacts such as blood vessels (Quick ROI); and (III) a manually outlined ROI following the synovial capsule of the knee joint (Precise ROI). Intra- and inter-reader agreement was assessed using the intra-class correlation coefficient (ICC).Results: The IRE from the Quick ROI and the Precise ROI revealed high correlations to the grade of histological inflammation (Spearman’s correlation coefficient (rho) = 0.70, p = 0.001 and rho = 0.74, p = 0.001, respectively). Intra- and inter-reader ICCs were very high (0.93–1.00). No Whole slice parameters were correlated to histology.Conclusion: DCE-MRI provides fast and accurate assessment of synovial inflammation in RA patients. Manual outlining of the joint to omit large artefacts is necessary.

Effect of concentration of contrast agent on the inflow effect for measuring absolute perfusion by use of inversion recovery T1-weighted TurboFLASH images

Previous studies have shown that the organ blood flow (OBF) calculated from the T₁-weighted MRI technique was lower than expected. The inflow correction was one of the main corrections for measuring the absolute OBF. Our aim in this study was to investigate the influence of the contrast agent concentration on inflow effect on signal intensity (SI) and to find the gradient of different flow rates at different concentrations by use of inversion recovery T₁-weighted turbo fast low angle shot (TurboFLASH) MRI images. We performed these studies at six different concentrations of gadolinium-diethylenetriamine-pantaacetic acid (Gd-DTPA) to find the inflow effect on the SI. A flow phantom made of Perspex was designed that produced four different flow rates at the same time. The non-uniformity of the clinical head and neck coil was measured and applied to the SI for measuring the corrected SI. The corrected SI was measured at different flow rates and concentrations. The results indicated that an increase in the flow rate and in the concentration of the contrast agent was associated with an increase in the gradient of the flow rate. The results also indicated that the inflow correction could be ignored when the concentration was low for measurement of the absolute OBF. At high concentrations, the inflow effect should be considered in calculations of the absolute OBF.

In Vitro Comparison of Water Displacement Method and 3 Tesla MRI for MR-Volumetry of the Olfactory Bulb: Which Sequence Is Appropriate?

Magnetic resonance imaging olfactory bulb (OB) volumetry (OBV) is already used as a complementary prognostic tool to assess olfactory disorders. However, a reference standard in imaging for OBV has not been established. The aim of this in vitro study was to compare volumetric results of different magnetic resonance sequences for OBV at 3 T to genuine OB volumes measured by water displacement.The volumes of 15 human cadaveric OBs were measured using the water displacement method in this institutional review board-approved prospective study. The magnetic resonance imaging protocol at 3 T included constructive interference in steady state (CISS), T2-weighted (T2w) three-dimensional (3D) sampling perfection with application-optimized contrasts using different flip-angle evolutions (SPACE), T2w two-dimensional (2D) turbo spin-echo (TSE), and T1-weighted (T1w) 3D fast low-angle shot (FLASH) sequences. Two blinded observers independently performed two OB volumetric assessments per bulbus and sequence. Intraobserver and interobserver reliabilities were assessed by intraclass correlation coefficients. Bland-Altman plots were analyzed to evaluate systematic biases and concordance correlation coefficients to assess reproducibility.For both observers, intraclass correlation coefficient analysis yielded almost perfect results for intraobserver reliability (CISS, 0.94-0.98; T2w 3D SPACE, 0.93-0.98; T2w 2D TSE, 0.98-0.98; T1w 3D FLASH, 0.95-0.99). Interobserver reliability showed almost perfect agreement for all sequences (CISS, 0.98; T2w 3D SPACE, 0.89; T2w 2D TSE, 0.93; T1w 3D FLASH, 0.97). The CISS sequence yielded the highest mean concordance correlation coefficient (0.95) and the highest combination of precision (0.97) and accuracy (0.98) values. In comparison with the water displacement method, Bland-Altman analyses revealed the lowest systematic bias (-0.5%) for the CISS sequence, followed by T1w 3D FLASH (-1.3%), T2w 3D SPACE (-7.5%), and T2w 2D TSE (-10.9%) sequences.Compared to the water displacement method, the CISS sequence is suited best to validly and reliably measure OB volumes because of its highest values for accuracy and precision and lowest systematic bias.

MR-compatible Assistance System for Biopsy in a High-Field-Strength System: Initial Results in Patients with Suspicious Prostate Lesions

To examine the feasibility and safety of magnetic resonance (MR)-guided biopsy by using a transgluteal approach in patients with suspicious prostate lesions by using an MR-compatible robotic system and a 1.5-T MR system. The study was approved by the institutional review board of University Frankfurt, and informed consent was obtained from each patient. A total of 20 patients (age range, 57.8-71.9 years; mean age, 65.1 years) underwent biopsy in a closed-bore high-field-strength MR system. Biopsy was performed with an MR-compatible pneumatically driven robotic system. T1-weighted gradient-echo fast low-angle shot and T2-weighted true fast imaging with steady-state precession sequences were used to plan and guide the intervention with a transgluteal access on the external planning computer of the assistance system. The system calculated the trajectory and then moved the guiding arm to the insertion point. The cannula was advanced manually, and biopsies were performed with the coaxial technique by using a 15-gauge pencil tip needle. Intervention time, complications, and biopsy findings were documented. The MR-compatible robotic system did not interfere with image quality, nor did MR imaging cause dysfunction of the robot. In one patient, the interventionist caused a fail-safe system shutdown. This was due to inadvertent displacement of the guiding arm during cannula insertion. This problem was solved by increasing the displacement threshold. Accurate coaxial cannula biopsy could be performed in all subsequent patients. Sufficient histopathologic assessment was performed in 19 patients. Insufficient material was retrieved in the patient who experienced fail-safe system shutdown. The median intervention time was 39 minutes (23-65 minutes). No procedure-related complications were observed. Preliminary results indicate that MR-guided robot-assisted biopsy is feasible and can be performed safely with highly accurate cannula placement.

Ideal combination of sequences for perianal fistula classification and evaluation of additional findings for readers with varying experience

The aim of our study was to assess the contribution of various magnetic resonance imaging (MRI) sequences in determining the type of perianal fistula and in obtaining critical information for surgical decisions, as well as to define the optimal combination of sequences for readers with varying levels of experience. The study included 33 MRI examinations in 26 patients with suspected perianal fistula. The following sequences were obtained in both the coronal and axial planes: thin slice, high resolution T1-weighted (W) spin echo; T2-weighted turbo spin echo; short tau inversion recovery (STIR); and native and contrast enhanced T1-weighted gradient echo fast low-angle shot (FLASH) images with fat suppression (FS-CE-T1W-GRE). The examinations were interpreted by three radiologists with varying degrees of experience in two different sessions, and the inter-reader agreement was assessed. Seventeen of the patients underwent surgery. The agreement between the surgical findings and the MRI results were evaluated. A statistically significant concordance between the fistula classification and surgery was achieved with the FS-CE-T1W-GRE sequence for Reader 1 (Cramer's V=0.701, P = 0,022) and Reader 3 (Cramer's V=0.716, P = 0,043). For Reader 2, statistically significant concordance between fistula classification and surgery was achieved with the FS-CE-T1W-GRE (Cramer's V=0.703, P = 0,011) and the T2W images (Cramer's V=0.648, P = 0,027). For all sequences, there was statistically significant agreement between readers for fistula classification, internal opening location, and the presence of sinus tracts, abscess, a horseshoe component, and inflammation. For experienced readers, combining FS-CE-T1W-GRE images with either T2W or STIR images collected in both the coronal and axial planes was sufficient to make an assessment before deciding the surgical extent of the procedure.

Magnetic Resonance Mammography of Invasive Lobular Versus Ductal Carcinoma

Invasive lobular (ILC) and ductal carcinomas (IDC) are the most frequent subtypes of breast cancer. Diagnosis of ILC is often challenging. This study was conducted to (1) evaluate dynamic and morphologic profiles and to (2) compare the diagnostic accuracy of IDC and ILC in magnetic resonance mammography (MRM). Our database consisted of all consecutive MRMs over a 12-year period (standardized protocol: T1-weighted fast low-angle shot; 0.1-mmol gadolinium-diethylenetriaminepentaacetate per kilogram of body weight; T2-weighted turbo spin-echo, 1.5 T; histological verification after MRM), which were evaluated by experienced (>500 MRMs) radiologists in consensus, applying 17 predefined descriptors. All the patients gave written consent; this study was approved by the local institutional review board. Extracting all the ILCs (n = 108), IDCs (n = 347), and benign lesions (n = 436) from the database, the data set of the study was created.In ILC and IDC diagnostic accuracy of single descriptors was calculated and compared separately (chi test). Using all the descriptors, a combined binary logistic regression analysis was applied to calculate the overall diagnostic accuracy for ILC and IDC. The corresponding areas under the curve were compared. ILC and IDC, showed wash-in and an irregular shape without difference (P = 1.0 and P = 0.4). Wash-out was more typical of IDC (72.6%; ILC, 57.4%; P = 0.007). Perifocal edema was diagnosed more frequently in IDC (45.5%; P = 0.05). For overall accuracy, the areas under the curve were 0.929 for ILC and 0.939 for IDC (P = 0.5). The dynamic and morphologic profiles of ILC and IDC were overlapping, and minor differences between both subgroups could be identified. Accordingly, the overall diagnostic accuracy of MRM was high and without difference between both subtypes of breast cancer.

In vitro Assessment of Artifacts from Commercially Available Markers for Image-guided Preoperative Marking of Bone and Soft Tissue Lesions

To evaluate the magnetic resonance (MR) imaging artifacts from several commercially available MR imaging-compatible and non-MR imaging-compatible markers for image-guided marking of soft tissue lesions at different field strengths and sequences. Ten different marking devices (anchor, coil, V, and X shapes) were injected into solid agar and imaged at two different field strengths (1.5 T, 3.0 T) and with three MR sequences (T1-weighted three-dimensional fast low-angle shot, T1-weighted two-dimensional fast low-angle shot MR fluoroscopy, and T2-weighted short inversion time inversion-recovery). Artifacts were assessed quantitatively by evaluating the areas of signal extinction and calculating equivalent diameters and qualitatively by visual grading. Paired t tests were used to assess the influence of sequence types and field strengths. Artifact diameters ranged from negligible to 45.8 mm. Sequence types and field strength did not have a statistically relevant influence on the artifact size. All artifacts from non-MR imaging-compatible V- and X-shaped markers were rated as "too large;" the artifacts from MR imaging-compatible V- and X-shaped markers and from all anchor-shaped devices were rated as "too small." The highest ratings were achieved by an MR imaging-compatible coil-shaped marker. The artifacts of the tested marking devices are mainly determined by their shapes and materials. Sequence types and field strengths have only a small influence on the artifacts. The most distinguished signal voids with an intermediate size resulted from an MR imaging-compatible coil-shaped marker.

Diffusion‐weighted MRI for tumour volume delineation: Comparison with morphological MRI

Diffusion-weighted magnetic resonance imaging (dwMRI) is sensitive to tissue microstructure on the cellular level and may therefore help to define biological tumour subvolumes and add complementary information to morphology-based cancer treatment protocols and therapy monitoring. The purpose of this study was therefore to evaluate the potential of dwMRI as compared with morphological MRI (mMRI) for tumour volume delineation using a nude rat human tumour xenograft model. Sixteen tumour-bearing rats (10 H1299, six FaDu) were examined with mMRI (T2-weighted true fast imaging with steady precession (TrueFISP), T1-weighted fast low angle shot (FLASH), T2-weighted dual echo steady state (DESS)) and echo-planar dwMRI in a clinical scanner at 1.5 T. For each method, we compared tumour volume and intra- and inter-observer variability of tumour outer edge delineation (disregarding intra-tumoural structure) as well as tumour signal-to-noise ratio (SNR) and tumour-to-muscle contrast-to-noise ratio (CNR). Tumours were visualised with significantly higher SNR and CNR in dwMRI. Median tumour volumes as measured by dwMRI (3.5 cm(3)) and mMRI (TrueFISP: 3.3 cm(3); FLASH: 3.3 cm(3); DESS: 3.2 cm(3)) were not significantly different and significantly correlated. Related to partial volume effects, the intra- and inter-observer variability of dwMRI (intra/inter: 12%/12%) was larger than for mMRI (TrueFISP: 4%/4%; FLASH: 5%/5%; DESS: 5%/5%). In conclusion, dwMRI allows tumour delineation with overall volume estimation comparable with mMRI approaches but slightly higher observer variability. Thus, besides tumour outline, it may potentially supplement morphology-based therapy planning and monitoring with additional biological information.

Magnetic resonance imaging of breast cancer and correlation with prognostic factors

Prognostic factors of breast cancer have been used for the prediction of clinical outcome or selection of patients for complementary treatment. Some of the imaging features of breast cancer, e.g. magnetic resonance imaging (MRI), are associated with these prognostic factors. To evaluate the relationship between dynamic enhanced MR features and prognostic factors of clinical outcome of breast cancer. A total of 136 patients with 151 breast cancers underwent 1.5T dynamic MR imaging with the use of a dynamic T1-weighted three-dimensional fast low-angle shot (FLASH) subtraction imaging technique. Morphological and kinetic analyses of MR features were evaluated using the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) MRI lexicon. Pathological prognostic factors were correlated with MR imaging characteristics, including tumor size, histological grade, lymph node status, expression of estrogen receptor (ER), expression of progesterone receptor (PR), expression of c-erbB2, determination of Ki-67 index, and microvascular density (MVD), using univariate and multivariate statistical analyses. Based on univariate and multivariate analyses, spiculated tumor margins correlated significantly with lower histological grade (I-II) and positive PR expression. Rim enhancement was significantly correlated with high histological grade, presence of axillary lymph node metastasis, large tumor size, increased Ki-67 index, and increased MVD. Early peak enhancement, as seen on the first scan after contrast medium injection, was correlated with negative ER expression. The presence of a lesion with a spiculated margin may predict a relatively good prognosis, and the presence of a lesion with rim enhancement may predict a relatively poor prognosis.

Correlation between Pancreatic Microcirculation and Type 2 Diabetes in Patients with Coronary Artery Disease: Dynamic Contrast-enhanced MR Imaging

To evaluate pancreatic perfusion by using dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging with pharmacokinetic modeling in coronary artery disease (CAD) patients with and those without type 2 diabetes to determine which perfusion parameter alterations might be associated with type 2 diabetes. This prospective study was approved by the responsible institutional review board. Written informed consent was obtained from all patients. All patients studied had CAD documented at conventional angiography. DCE MR with a two-dimensional T1-weighted fast low-angle shot sequence in oblique axial planes was used to assess pancreatic microcirculation in patients with and those without type 2 diabetes (age +/- standard deviation, 60.8 years +/- 11.2 and 61.8 years +/- 11.2, respectively; 20 men and five women in each group). Microcirculatory quantitative parameters, including volume transfer constant (K(trans), in min(-1)), extravascular extracellular space volume per unit volume of tissue (v(e)), and plasma volume per unit volume of tissue (v(p)) were compared between groups by using independent-sample t tests. Patients with diabetes had a significantly higher K(trans) (0.977 vs 0.696, P = .031) and a lower v(p) (0.057 vs 0.084, P = .005) compared with patients without diabetes. A borderline difference in v(e) was found between the diabetes and nondiabetes groups (0.141 vs 0.103, P = .05). Among the 25 patients with diabetes, those who had the condition for more than 10 years (n = 11) had significantly higher K(trans) and v(e) than did those who had diabetes for less than 10 years (n = 14) (1.145 vs 0.783 and 0.174 vs 0.108; P = .04 and .02, respectively). DCE MR imaging demonstrated increased endothelial permeability and decreased plasma volume in the pancreas in CAD patients with type 2 diabetes; patients with a history of diabetes for more than 10 years showed further increase in endothelial permeability.

Age-related Iron Deposition in the Basal Ganglia: Quantitative Analysis in Healthy Subjects

To determine the values of iron accumulation in the basal ganglia of healthy volunteers of different ages with R2* and raw signal intensity measurements from T1-weighted magnetic resonance (MR) images, supported by voxel-based relaxometry (VBR), and to compare them with previously reported iron concentrations found in autopsy material. The ethics committee approved the study, and the participants or their parents gave written informed consent. Eighty subjects (41 female and 39 male subjects; age range, 1-80 years) were examined at 1.5 T. For each subject, R2* values were calculated. Curves for R2* versus age were obtained for globus pallidus (GP), putamen, caudate nucleus, substantia nigra (SN), and frontal white matter (FWM). To highlight possible differences in iron concentration among the age decades, VBR was applied. Signal intensity values were estimated on T1-weighted fast low-angle shot images, and regions of interest were drawn in each nucleus. R2* values were also compared with iron concentrations reported in a postmortem study. Statistical analysis was performed (t test), and a difference with P < .05 (FDR corrected) was significant. The curves for R2* versus age showed an exponential increase with increasing age in all the basal ganglia. VBR demonstrated significant differences (P < .05, corrected) in the comparison between the 2nd and the following decades for lenticular nuclei. Good correlation coefficients were found for GP (R(2) = 0.64), putamen (R(2) = 0.51), and SN (R(2) = 0.53) when compared with findings in the postmortem study. Signal intensity curves were similar to the R2* curves. R2* measurements can be used to quantify brain iron accumulation and thus may allow better evaluation of neurodegenerative diseases associated with iron deposition.

Functional MRI: Evaluation of Chronic Kidney Disease with Perfusion Imaging

To evaluate the functional alterations of chronic kidney disease (CKD) with magnetic resonance dynamic perfusion imaging. Twenty-one healthy subjects (42 kidneys) and 20 CKD patients (40 kidneys) underwent routine scans with fat-saturated T1-weighted fast low angle shot (FLASH) and true-fast imaging with steady-state precession (FISP) sequences followed by dynamic perfusion scans using a turbo-FLASH T1-weighted sequence. Signal intensity (SI) of the cortex and medulla on images was measured and plotted as a function of time. Peak height (P) and time to peak (T) of the cortex and medulla SI were estimated, and P/T ratio and the area under the time-intensity curves were calculated. We also tested the correlation between these data and serum creatinine (sCr) levels in patients. P, P/T ratio, and the area under the curve of patients' cortex and medulla were significantly decreased compared to control subjects, and T was delayed. In patients, P and P/T ratio of the cortex and P of the medulla were negatively correlated with sCr levels (r = -0.469, r = -0.419, and r = -0.423, respectively; P < 0.01). Renal dysfunction in CKD can be evaluated by magnetic resonance dynamic perfusion imaging.

Direct MR Galactography: Feasibility Study

To compare T1- and T2-weighted direct magnetic resonance (MR) galactography, indirect MR galactography, and conventional galactography in women with pathologic nipple discharge. The study was approved by the institutional review board. Written informed consent was obtained from all patients. Twenty-three women (age range, 30-85 years) with pathologic nipple discharge and pathologic conventional galactographic findings underwent physical examination, ultrasonography, and MR imaging before surgery. A T2-weighted sequence of the affected breast was performed before (indirect MR galactography), and T1- and T2-weighted sequences were performed after (direct MR galactography), gadopentetate dimeglumine was injected into the discharging duct. MR galactographic findings were analyzed and compared with conventional galactographic findings. Sequences used were T2-weighted three-dimensional constructive interference in steady state (CISS), T1-weighted volumetric interpolated breath-hold examination (VIBE), and T1-weighted fast low-angle shot (FLASH). The 23 patients had a total of 57 findings at conventional galactography. Indirect MR galactography with CISS showed pathologic findings in eight (42%) of 19 patients and showed 15 (33%) of 46 of all findings. Direct MR galactography with CISS showed pathologic findings in 23 (100%) of 23 patients and 47 (82%) of 57 of all findings, that with VIBE showed pathologic findings in 19 (83%) of 23 patients and 38 (67%) of 57 of all findings, and that with FLASH showed pathologic findings in 16 (100%) of 16 patients and 31 (80%) of 39 of all findings. There was a significant (P < .01) difference between indirect MR galactography and all direct MR galactography sequences in the detection of ductal disease. Eight (35%) of 23 women showed additional findings at direct MR galactography in comparison with standard MR imaging sequences. MR galactography has the potential to be used in the diagnostic work-up of pathologic nipple discharge. Direct MR galactography shows more disease than does indirect MR galactography. The highest detection rate for ductal disease compared with that at conventional galactography was found with the direct MR galactography CISS and FLASH sequences.

Evaluation of carotid vessel wall enhancement with image subtraction after gadobenate dimeglumine-enhanced MR angiography

Objectives This study was aimed at testing the value of image subtraction for evaluating carotid vessel wall enhancement in contrast-enhanced MR angiography (MRA). Materials and methods IRB approval was obtained. The scans of 81 consecutive patients who underwent carotid MRA with 0.1 mmol/kg of gadobenate dimeglumine were reviewed. Axial carotid 3D T1-weighted fast low-angle shot sequence before and 3 min after contrast injection were acquired and subtracted (enhanced minus unenhanced). Vessel wall enhancement was assigned a four-point score using native or subtracted images from 0 (no enhancement) to 3 (strong enhancement). Stenosis degree was graded according to NASCET. Results With native images, vessel wall enhancement was detected in 20/81 patients (25%) and in 20/161 carotids (12%), and scored 2.0 ± 0.6 (mean ± standard deviation); with subtracted images, in 21/81 (26%) and 22/161 (14%), and scored 2.5 ± 0.6, respectively ( P < 0.001, Sign test). The overall stenosis degree distribution was: mild, 41/161 (25%); moderate, 77/161 (48%); severe, 43/161 (27%). Carotids with moderate stenosis showed vessel wall enhancement with a frequency (17/77, 22%) significantly higher than that observed in carotids with mild stenosis (1/41, 2%) ( P = 0.005, Fisher exact test) and higher, even though with borderline significance ( P = 0.078, Fisher exact test), than that observed in carotids with severe stenosis (4/43, 9%). Conclusion Roughly a quarter of patients undergoing carotid MRA showed vessel wall enhancement. Image subtraction improved vessel wall enhancement conspicuity. Vessel wall enhancement seems to be an event relatively independent from the degree of stenosis. Further studies are warranted to define the relation between vessel wall enhancement and histopathology, inflammatory status, and instability.

Correlation between High Resolution Dynamic MR Features and Prognostic Factors in Breast Cancer

ObjectiveTo correlate high resolution dynamic MR features with prognostic factors in breast cancer.Materials and MethodsOne hundred and ninety-four women with invasive ductal carcinomas underwent dynamic MR imaging using T1-weighted three-dimensional fast low-angle shot (3D-FLASH) sequence within two weeks prior to surgery. Morphological and kinetic MR features were determined based on the breast imaging and reporting data system (BI-RADS) MR imaging lexicon. Histological specimens were analyzed for tumor size, axillary lymph node status, histological grade, expression of estrogen receptor (ER), expression of progesterone receptor (PR), and expression of p53, c-erbB-2, and Ki-67. Correlations between the MR features and prognostic factors were determined using the Pearson χ2 test, linear-by-linear association, and logistic regression analysis.ResultsBy multivariate analysis, a spiculated margin was a significant, independent predictor of a lower histological grade (p < 0.001), and lower expression of Ki-67 (p = 0.007). Rim enhancement was significant, independent predictor of a higher histological grade (p < 0.001), negative expression of ER (p = 0.001), negative expression of PR (p < 0.001) and a larger tumor size (p = 0.006). A washout curve may predict a higher level of Ki-67 (p = 0.05). Most of the parameters of the initial enhancement phase cannot predict the status of the prognostic factors. Only the enhancement ratio may predict a larger tumor size (p = 0.05).ConclusionOf the BI-RADS-MR features, a spiculated margin may predict favorable prognosis, whereas rim enhancement or washout may predict unfavorable prognosis of breast cancer.

Usefulness of Fat-Suppressed T1-Weighted MRI Using Orally Administered Superparamagnetic Iron Oxide for Revealing Ampullary Carcinomas

To evaluate the value of adding fat-suppressed (FS) T1-weighted magnetic resonance imaging (MRI) with orally administered superparamagnetic iron oxide (SPIO) to the 3-dimensional dynamic MRI for revealing ampullary carcinomas. Twenty-five patients with ampullary carcinoma who underwent MRI with orally administered SPIO, including a FS T1-weighted fast low-angle shot (FLASH) sequence, a respiratory-triggered turbo spin-echo (RT-TSE) sequence, and the 3-phasic 3-dimensional dynamic images, were enrolled in this study. About 5 min before the examination, a mixture of 8.4 mg of SPIO and 300 mL water was administered orally to all patients. The images were compared quantitatively by measuring the tumor-pancreas (duodenum) contrast-to-noise ratio and, qualitatively, by evaluating tumor conspicuity. Three separate sets of images, that is, the dynamic set, the combination of the dynamic set, and the RT-TSE, and the combination of the dynamic set and the FLASH were analyzed by 2 observers in consensus. For the tumor-pancreas (duodenum) contrast-to-noise ratio, the FLASH was significantly higher than those of the dynamic set and RT-TSE (P < 0.05). The tumor conspicuity with the combination of the dynamic set and the FLASH was also significantly better than those of the dynamic set, and the combination of the dynamic set and RT-TSE (P = 0.001). For 15 tumors that were surgically confirmed, the combined reading of the FLASH imaging and dynamic set allowed more accurate surgical staging (14/15, 93.3%) than did the dynamic imaging set or the combined reading of the dynamic set and RT-TSE (11/15, 73.3%). Addition of the FS FLASH image using orally administered SPIO to the dynamic MRI is useful for revealing ampullary carcinoma.

Evaluation of normal brain development by prenatal MR imaging

The aim of this study was to describe the normal pattern of development and maturation of the foetal brain with respect to gestational age as assessed with magnetic resonance imaging (MRI) and to provide an overview of the possibilities of the technique. Foetal cerebral MRI was performed on 56 pregnant women between 19 and 37 weeks of gestation. Half-Fourier single-shot turbo spin-echo (HASTE), true fast imaging with steady precession (FISP), T1-weighted fast low angle shot (FLASH) two-dimensional (2D) and diffusion-weighted (DW) sequences with apparent diffusion coefficient (ADC) were obtained. Biometric parameters and developmental areas of the cerebral cortex were correlated to gestational age by using the Spearman rank correlation test. We found a negative correlation between the germinal matrix/biparietal diameter ratio and gestational age and a positive correlation between the germinal and cortical matrix when expressed as external intraocular diameter ratio (R=0.452, p=0.02). The cortical mantle was correlated with biometric parameters, such as the biparietal diameter and the frontooccipital diameter, and with gestational age. The interhemispheric fissure, the parietooccipital fissure and the sylvian fissure were detectable by the 22nd week. In the grey matter, the mean ADC values varied from 1.76 x 10(-3) mm(2)/s (at week 19) to 0.89 x 10(-3) mm(2)/s (at week 37), whereas in the white matter, the values varied from 2.03 x 10(-3) mm(2)/s (at week 19) to 1.25 x 10(-3) mm(2)/s (at week 37). MRI provides a reliable valuation of brain maturation during pregnancy.

Differentiation of SCA2 from MSA‐C using proton magnetic resonance spectroscopic imaging

To assess and compare biochemical and volumetric features of the cerebellum in patients with spinocerebellar ataxia type 2 (SCA2) and patients with the cerebellar variant of multiple system atrophy (MSA-C). Nine genetically assigned SCA2 patients and six MSA-C patients who met the clinical criteria of MSA-C underwent a clinical and neuroradiological workup with respect to cerebellar features. The MR protocol consisted of a sagittal T1-weighted three-dimensional fast low-angle shot (3D FLASH) sequence and a transversal T2- and spin-density-weighted turbo spin-echo sequence. The proton magnetic resonance spectroscopic imaging ((1)H-MRSI) protocol consisted of two chemical shift imaging (CSI) sequences (echo time (TE) = 20 and 135 msec). Both short- and long-TE MR spectroscopy (MRS) images showed significant decreases in values for N-acetylaspartate to creatine (NAA/Cr), and choline to creatine (Cho/Cr) ratios in MSA-C and SCA2 compared to normal controls, though there was no difference between the two patient groups. In contrast, distinct cerebellar lactate (Lac) peaks were detected in seven SCA2 patients, and small peaks were detected in two. However, we did not detect any definite Lac peak in MSA-C or control subjects. MRSI revealed Lac pathology in SCA2 but not in MSA-C. Whether this indicates distinct pathogenetic mechanisms of cerebellar degeneration remains to be established.

Irreversible Myocardial Injury: Assessment with Cardiovascular Delayed-Enhancement MR Imaging and Comparison of 1.5 and 3.0 T—Initial Experience

To prospectively compare visualization and quantification of irreversible myocardial injury in patients with chronic myocardial infarction at 1.5- and 3.0-T magnetic resonance (MR) imaging. The institutional research ethics committee approved the study. Participants gave written informed consent. Sixteen male patients (mean age, 66 years +/- 13 [standard deviation]) with myocardial infarction were imaged with the same sequence by the same operator at 1.5 and 3.0 T. After cine imaging, a bolus of gadodiamide was administered. Short-axis images of entire left ventricle (LV) were acquired with a breath-hold T1-weighted segmented inversion-recovery turbo fast low-angle shot (FLASH) sequence. Agreement for myocardial hyperenhancement (HE) mass between field strengths was assessed with Bland-Altman method; agreement for detection and transmural extent of HE was assessed with kappa statistics. Intra- and interobserver reproducibility of mass and transmural extent of HE were assessed at 1.5 and 3.0 T. Bland-Altman analysis revealed no systematic bias (mean difference, 0.2 g; 95% confidence interval: -0.7 g, 1.2 g) and acceptable limits of agreement (-3.3 to 3.8 g) between field strengths for HE mass. HE mass measurements were strongly correlated (R(2) = 0.99); there was no significant difference in measurements at 1.5 and 3.0 T (28.1 g +/- 15.7 [22.6% +/- 10.9 of LV mass] vs 27.8 g +/- 15.7 [22.3% +/- 10.7 of LV mass], respectively; P = .599). For all segments, there was a high degree of agreement for HE detection (kappa = 0.90) and transmural grade (kappa = 0.79) between field strengths. Intra- and interobserver variability were low between both field strengths. Initial inversion time selected to null the signal of normal myocardium at 3.0 T was 57 msec +/- 20 longer than at 1.5 T (P < .01). By using the same turbo FLASH MR pulse sequence, there was strong agreement in mass and transmural extent of myocardial HE between 1.5 and 3.0 T.

Effectiveness of MR imaging for diagnosing the mild forms of acute pancreatitis: Comparison with MDCT

To assess the usefulness of MRI and determine which MR sequence is most effective for diagnosing the mild forms of acute pancreatitis. Forty subjects (20 normal volunteers and 20 patients with a mild form of acute pancreatitis) underwent MRI with fat-suppressed T1-weighted fast low-angle shot (FLASH), half-Fourier acquisition single-shot turbo spin-echo (HASTE), and TSE short TI inversion recovery (TSE-STIR) sequences. The 20 patients with a mild form of acute pancreatitis underwent multidetector CT (MDCT) and MRI within a 24-hour interval. We qualitatively analyzed all of the images by assessing inflammatory changes in the pancreas and peripancreatic fat. We quantitatively compared differences in pancreas-liver contrast between the control and patient groups for each MR sequence by measuring the signal intensities of the pancreas and liver. TSE-STIR was the best of the four modalities for delineating peripancreatic and pancreatic inflammation (P < 0.01). TSE-STIR depicted definitive peripancreatic and pancreatic inflammation in 18 and 15 patients, respectively. MDCT depicted only three cases of peripancreatic inflammation. TSE-STIR was also produced the best the best quantitative results of the MR sequences (P = 0.09). MRI is helpful for diagnosing the mild forms of acute pancreatitis. We recommend the use of TSE-STIR imaging as part of the routine protocol for evaluating pancreatitis.