Three-dimensional Fast Spoiled Gradient Echo Research Articles

Detection of pathological contrast enhancement with synthetic brain imaging from quantitative multiparametric MRI.

We aimed to test whether synthetic T1-weighted imaging derived from a post-contrast Quantitative Transient-state Imaging (QTI) acquisition enabled revealing pathological contrast enhancement in intracranial lesions. The analysis included 141 patients who underwent a 3 Tesla-MRI brain exam with intravenous contrast media administration, with the post-contrast acquisition protocol comprising a three-dimensional fast spoiled gradient echo (FSPGR) sequence and a QTI acquisition. Synthetic T1-weighted images were generated from QTI-derived quantitative maps of relaxation times and proton density. Two neuroradiologists assessed synthetic and conventional post-contrast T1-weighted images for the presence and pattern of pathological contrast enhancement in intracranial lesions. Enhancement volumes were quantitatively compared. Using conventional imaging as a reference, synthetic T1-weighted imaging was 93% sensitive in revealing the presence of contrast enhancing lesions. The agreement for the presence/absence of contrast enhancement was almost perfect both between readers (k = 1 for both conventional and synthetic imaging) and between sequences (k = 0.98 for both readers). In 91% of lesions, synthetic T1-weighted imaging showed the same pattern of contrast enhancement visible in conventional imaging. Differences in enhancement pattern in the remaining lesions can be due to the lower spatial resolution and the longer acquisition delay from contrast media administration of QTI compared to FSPGR. Overall, enhancement volumes appeared larger in synthetic imaging. QTI-derived post-contrast synthetic T1-weighted imaging captures pathological contrast enhancement in most intracranial enhancing lesions. Further comparative studies employing quantitative imaging with higher spatial resolution is needed to support our data and explore possible future applications in clinical trials.

Lumbar dorsal root ganglion displacement between supine and prone positions evaluated with 3D MRI

ObjectivePre-operative lumbar spine MRI is usually acquired with the patient supine, whereas lumbar spine surgery is most commonly performed prone. For MRI to be used reliably and safely for intra-operative navigation for foraminal and extraforaminal decompression, the magnitude of dorsal root ganglion (DRG) displacement between supine and prone positions needs to be understood. MethodsA prospective study of a degenerative lumbar spine cohort of 18 subjects indicated for lumbar spine surgery. Three-dimensional T2-weighted fast spin echo and T1-weighted spoiled gradient echo sequences were acquired at 3 T. Displacement and cross-sectional area (CSA) of the bilateral DRGs at 5 motion levels (L1–2 to L5-S1) were determined via 3D segmentation by 2 independent evaluators. Wilcoxon rank-sum tests without correction for multiple comparison were performed against hypothesized 1-mm absolute displacement and corresponding 24% CSA change. ResultsDRG mean absolute displacement was <1 mm (p > 0.99, mean = 0.707 mm, 95% confidence interval (CI) = 0.659 to 0.755 mm), with the largest directional displacement in the dorsal-to-ventral direction from supine to prone (mean = 0.141 mm, 95% CI = 0.082 to 0.200 mm). Directional displacements caudal-to-cephalad were 0.087 mm (95% CI = 0.022 to 0.151 mm), and left-right were −0.030 mm (95%CI = −0.059 to −0.001 mm). Mean CSA change was within 24% (p > 0.99, mean = −8.30%, 95% CI = −10.5 to −6.09%). Mean absolute displacement was largest for the L1 (mean = 0.811 mm) and L2 (mean = 0.829 mm) DRGs. ConclusionsMinimal, non-statistically significant soft tissue displacement and morphological area differences were demonstrated between supine and prone positions during 3D lumbar spine MRI.

Usefulness of T2-Weighted Images with Deep-Learning-Based Reconstruction in Nasal Cartilage.

This study aims to evaluate the feasibility of visualizing nasal cartilage using deep-learning-based reconstruction (DLR) fast spin-echo (FSE) imaging in comparison to three-dimensional fast spoiled gradient-echo (3D FSPGR) images. This retrospective study included 190 set images of 38 participants, including axial T1- and T2-weighted FSE images using DLR (T1WIDL and T2WIDL, belong to FSEDL) and without using DLR (T1WIO and T2WIO, belong to FSEO) and 3D FSPGR images. Subjective evaluation (overall image quality, noise, contrast, artifacts, and identification of anatomical structures) was independently conducted by two radiologists. Objective evaluation including signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) was conducted using manual region-of-interest (ROI)-based analysis. Coefficient of variation (CV) and Bland-Altman plots were used to demonstrate the intra-rater repeatability of measurements for cartilage thickness on five different images. Both qualitative and quantitative results confirmed superior FSEDL to 3D FSPGR images (both p < 0.05), improving the diagnosis confidence of the observers. Lower lateral cartilage (LLC), upper lateral cartilage (ULC), and septal cartilage (SP) were relatively well delineated on the T2WIDL, while 3D FSPGR showed poorly on the septal cartilage. For the repeatability of cartilage thickness measurements, T2WIDL showed the highest intra-observer (%CV = 8.7% for SP, 9.5% for ULC, and 9.7% for LLC) agreements. In addition, the acquisition time for T1WIDL and T2WIDL was respectively reduced by 14.2% to 29% compared to 3D FSPGR (both p < 0.05). Two-dimensional equivalent-thin-slice T1- and T2-weighted images using DLR showed better image quality and shorter scan time than 3D FSPGR and conventional construction images in nasal cartilages. The anatomical details were preserved without losing clinical performance on diagnosis and prognosis, especially for pre-rhinoplasty planning.

Can magnetic resonance imaging after cranioplasty using titanium mesh detect brain tumors?

This study determined the dependence of the concentration and position of contrast-enhanced tumors on the radio frequency (RF)-shielding effect of titanium mesh using the contrast-to-noise ratio (CNR) in magnetic resonance imaging (MRI). A phantom was constructed by filling a plastic container with manganese chloride tetrahydrate and agar. Four cellophane cylindrical containers were arranged from the end of the plastic container, and the brain tumor model was filled with gadobutrol diluted with NaCl, with molarity values of 0.2-1.0mmol/L. The titanium mesh board was set on the left side of the phantom. Images were acquired using a 1.5-T MRI as well as two-dimensional spin-echo (2D SE) and three-dimensional fast spoiled gradient echo (3D FSPGR) sequences. CNR was calculated using the signal intensity values of the tumor model, surrounding area of the brain model, and background noise. Furthermore, the fractional change in CNR was calculated using values of CNR with and without the mesh. Moreover, a profile of CNR was created. The fractional change in CNR decreased at the brain tumor positions present near the mesh and at a contrast medium concentration of approximately ≤ 0.5mmol/L in 2D SE and ≤ 0.25mmol/L in 3D FSPGR. According to the CNR profiles, directly under the mesh, almost all contrast concentrations in 2D SE was unrecognizable; however, at a concentration of ≥ 0.5 mmol/L in 3D FSPGR was recognizable.

Multimodal MRI Assessment of Thalamic Structural Changes in Earthquake Survivors.

Moving from the central role of the thalamus in the integration of inner and external stimuli and in the implementation of a stress-related response, the objective of the present study was to investigate the presence of any MRI structural and volumetric changes of the thalamic structures in earthquake witnesses. Forty-one subjects were included, namely 18 university students belonging to the experimental earthquake-exposed group (8 males and 10 females, mean age 24.5 ± 1.8 years) and a control group of 23 students not living in any earthquake-affected areas at the time of the earthquake (14 males and 9 females, mean age 23.7 ± 2.0 years). Instrumental MRI evaluation was performed using a 3-Tesla scanner, by acquiring a three-dimensional fast spoiled gradient-echo (FSPGR) sequence for volumetric analysis and an EPI (echoplanar imaging) sequence to extract fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values. As compared to the control one, the experimental group showed significantly lower gray matter volume in the mediodorsal nucleus of the left thalamus (p < 0.001). The dominant hemisphere thalamus in the experimental group showed higher mean ADC values and lower mean FA values as compared to the control group.

Coronal Plane Magnetic Resonance Imaging Measurement of Hippocampal Formation Volume of Healthy Chinese Adults.

The aim of this study was to provide hippocampal formation volume data for the clinic and diagnoses of the related diseases for healthy Chinese adult. Three-dimensional fast-spoiled gradient echo magnetic resonance imaging sequence scanning was used in 68 cases of healthy adult brain to gain the image between lateral border of bilateral fourth ventricle and vitreous body. The image then was divided into 10 equal parts in the sagittal plane. We draw the outline and then obtain the area and volume of the hippocampal formation in each part, and the data were analyzed using SPSS 17.0 software. Results of the research showed that the volume of the hippocampal in healthy Chinese adult left side is ∼2319.87 to 2602.47 mm, right side is ∼2443.96 to 2755.89 mm; male left side is ∼2135.00 to 2494.29 mm, right side is -2350.21 to 2745.61 mm; female left side is ∼2328.13 to 2748.41 mm, right side is ∼2398.41 to 2909.48 mm. The volume of hippocampal absence correlated with age (P > 0.05), youth group. The volume of hippocampal has significant sexual difference (t = 2.500, P < 0.05). The volumes of the left and right sides have significant difference (t = 2.571, P < 0.05). For the female group (middle-age and youth), the volumes of right side hippocampal have significant difference (P < 0.05).

The development and optimisation of 3D black-blood R2* mapping of the carotid artery wall

PurposeTo develop and optimise a 3D black-blood R2* mapping sequence for imaging the carotid artery wall, using optimal blood suppression and k-space view ordering. MethodsTwo different blood suppression preparation methods were used; Delay Alternating with Nutation for Tailored Excitation (DANTE) and improved Motion Sensitive Driven Equilibrium (iMSDE) were each combined with a three-dimensional (3D) multi-echo Fast Spoiled GRadient echo (ME-FSPGR) readout. Three different k-space view-order designs: Radial Fan-beam Encoding Ordering (RFEO), Distance-Determined Encoding Ordering (DDEO) and Centric Phase Encoding Order (CPEO) were investigated. The sequences were evaluated through Bloch simulation and in a cohort of twenty volunteers. The vessel wall Signal-to-Noise Ratio (SNR), Contrast-to-Noise Ratio (CNR) and R2*, and the sternocleidomastoid muscle R2* were measured and compared. Different numbers of acquisitions-per-shot (APS) were evaluated to further optimise the effectiveness of blood suppression. ResultsAll sequences resulted in comparable R2* measurements to a conventional, i.e. non-blood suppressed sequence in the sternocleidomastoid muscle of the volunteers. Both Bloch simulations and volunteer data showed that DANTE has a higher signal intensity and results in a higher image SNR than iMSDE. Blood suppression efficiency was not significantly different when using different k-space view orders. Smaller APS achieved better blood suppression. ConclusionThe use of blood-suppression preparation methods does not affect the measurement of R2*. DANTE prepared ME-FSPGR sequence with a small number of acquisitions-per-shot can provide high quality black-blood R2* measurements of the carotid vessel wall.

Pulse sequence considerations for simulation and postimplant dosimetry of prostate brachytherapy

PurposeThe purpose of this work is to present a brief review of MRI physics principles pertinent to prostate brachytherapy, and a summary of our experience in optimizing protocols for prostate brachytherapy applications. Methods and MaterialsWe summarized essential MR imaging characteristics and their interplays that need to be considered for prostate brachytherapy applications. These include spatial resolution, signal-to-noise ratio, image contrast, artifacts, geometric distortion, specific absorption rate, and total scan time. We further described the optimization of the protocols for three pulse sequences: three-dimensional (3D) fast-spoiled gradient echo sequence for T1-weighted imaging, 3D fast-spin echo sequence for T2-weighted imaging, and 3D fast imaging in steady-state precession sequence for combined T1 and T2-weighed imaging. The utilization of an endorectal coil was also described. ResultsUsing the optimized protocols, we acquired high-quality images of the entire prostate within 3–5 minutes for each sequence. These images display the desired image contrasts and a spatial resolution that is equal to or better than 0.59 mm × 0.73 mm × 1.2 mm. While 3D fast-spoiled gradient echo sequence and 3D fast-spin echo sequence depict radioactive seed markers and anatomic structures separately, 3D fast imaging in steady-state precession sequence demonstrates great promise for imaging both seed markers and prostate anatomy simultaneously in a single acquisition. ConclusionsWe have optimized current MRI protocols and demonstrated that the anatomic structures and positive contrast radioactive seed markers for prostate post-implant dosimetry can be adequately imaged either separately or simultaneously using different pulse sequences within a total scan time of 3–5 minutes each.

The Coronal Plane Magnetic Resonance Imaging Measurement of Hippocampal Formation Volume

The aim of this study was to provide healthy Chinese adult hippocampal formation volume data for the clinic and diagnoses of the related diseases. Three-dimensional fast spoiled gradient echo magnetic resonance imaging sequence scanning was used in 68 cases of healthy adult brain to gain the image between lateral border of bilateral fourth ventricle and vitreous body. The image then was divided into 10 equal parts in the sagittal plane. We draw the outline and then obtain the area and volume of the hippocampal formation in each part, and the data were analyzed by SPSS 17.0 software. Results of the research showed that the volume of the hippocampal in healthy Chinese adult left side is ≈ 2319.87 to 2602.47 mm3, right side is ≈ 2443.96 to 2755.89 mm3; male left side is ≈ 2135.00 to 2494.29 mm3, right side is ≈ 2350.21 to 2745.61 mm3; female left side is ≈ 2328.13 to 2748.41 mm3, right side is ≈ 2398.41 to 2909.48 mm3. The volume of hippocampal absence correlated with age (P > 0.05), youth group. The volume of hippocampal has significant sexual difference (t = 2.500, P < 0.05). The volumes of the left and right sides have significant difference (t = 2.571, P < 0.05). The female group (middle-age and youth) which the volumes of right-side hippocampal have significant difference (P < 0.05).

Changes of brain gray matter structure in Parkinson's disease patients with dementia.

Voxel-based morphometry is gaining considerable interest for studies examining Parkinson's disease dementia patients. In this study, 12 patients with clinically defined Parkinson's disease and dementia and 12 non-demented patients with Parkinson's disease were examined using a T1WI three-dimensional fast spoiled gradient echo sequence. Gray matter data were analyzed using a voxel-based morphometry method and independent sample t-test based on Statistical Parametric Mapping 5 software. Differences in gray matter volume were represented with statistical parametric mapping. Compared with Parkinson's disease patients without dementia, decreased gray matter volume in Parkinson's disease dementia patients was observed in the bilateral superior temporal gyrus, bilateral posterior cingulate and left cingulate gyrus, right parahippocampal gyrus and hippocampus, right precuneus and right cuneus, left inferior frontal gyrus and left insular lobe. No increased gray matter volume was apparent. These data indicate that gray matter atrophy in the limbic system and cerebral neocortex is related to the presence of dementia.

OPTIMAL CONCENTRATIONS OF GADOVIST IN T1-WEIGHTED MAGNETIC RESONANCE IMAGING: PHANTOM STUDY AND COMPUTER SIMULATION

Contrast-Enhanced Magnetic Resonance Imaging (CE-MRI) has been widely used in the diagnosis of lesions. Many contrast agents with various chemical and pharmacokinetic properties have been developed for clinical use. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) after the contrast agent administration depend on many factors, e.g. category and injected dosage of contrast agents, field strength of magnetic resonance (MR) scanner, slew rate of gradient, type of radiofrequency coil, reconstruction algorithm, pulse sequences, and so on. Gadovist is a newly developed contrast agent with high formulation of 1.0 M. It has been used in MR angiography and perfusion studies. The aim of this study is to investigate the optimal concentrations of Gadovist in MR T1-weighted (T1W) images from phantom study and computer simulation. A phantom made of 21 test tubes with various concentrations of Gadovist (0–160 mM) was investigated. All the studies were performed on a 1.5-T clinical whole-body scanner. Four T1W pulse sequences, including two-dimensional spoiled gradient echo (2DSPGR), three-dimensional fast spoiled gradient echo (3DFSPGR), conventional spin echo (CSE), and inversion recovery (IR) were employed to produce T1W images. The CNR values were calculated from regions of interest (ROIs) of all test tubes and the optimal concentration for each pulse sequence was determined. The T1 and T2 values of the phantom were also measured to obtain the relaxivities (r1 and r2). Afterward, the optimal concentration for each pulse sequence could be obtained from computer simulation by using the r1 and r2 values. The results showed that the measured optimal concentrations for 2DSPGR, 3DFSPGR, CSE and IR are 10, 20, 2.5, and 2.5 mM, respectively. The r1 and r2 values of the Gadovist phantom are 4.1 and 5.7 mM-1s-1, respectively. The optimal concentrations obtained from computer simulation are 13.5, 22.8, 2.0, and 2.7 mM for 2DSPGR, 3DFSPGR, CSE, and IR, respectively. The optimal concentrations obtained from computer simulation and phantom study are in good agreement.

T2 mapping of articular cartilage in knee osteoarthritis using a magnetic resonance staging.

To evaluate T2 mapping of articular cartilage in knee osteoarthritis (OA). Totally 38 healthy subjects (group H) and 53 OA patients received scoring with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)and underwent T2 mapping of tibiofemoral articular cartilages. The T2 values in 10 subregions of the cartilages were measured. Patients in the OA group were further divided into OA1 group and OA2 group using the modified Magnetic Resonance Recht Grading System. In OA group, the fat-suppressed three-dimensional fast spoiled gradient echo MRI was performed to obtain the modified Whole-Organ Magnetic Resonance Imaging Score (WORMS). The differences of T2 values among group H, group OA1, and group OA2 were compared. The correlation between T2 value and WORMS/WOMAC scores was analyzed. The intra- and inter-observer reproducibility of measurement was calculated. The T2 values in all the subregions ranged 43.9-53.6ms in group H, 41.1-55.0 ms in group OA1, and 45.6-56.1ms in group OA2. T2 values in group OA2 were significantly higher in central medial femoral subregion, central medial, and lateral tibial subregions compared with group H, also significantly higher in central medial femoral subregion, anterior and central medial tibial subregions compared with group OA1 (P<0.05). T2 values were significantly correlated with WORMS scores (R=0.307-0.811, P<0.01) except in posterior lateral femoral subregion, but not with WOMAC scores. The correlation coefficients for intra- and inter-observer measurement showed good reproducibility (R>0.740, P<0.05) except in anterior lateral tibial subregion for inter-observer of measurement. T2 mapping can differentiate the OA severity of knee cartilage using a magnetic resonance staging, and therefore can be a sensitive technique for monitoring the severity of OA.

Inflammatory breast cancer: defining breast magnetic resonance imaging features.

Abstract Abstract #4008 PURPOSE: &amp;#x2028; Inflammatory breast carcinoma (IBC) is an aggressive cancer with radiological and clinical features of a heterogeneous disease. The clinical presentation of IBC is characterized by the sudden onset of breast erythema and edema, often without an associated palpable breast mass. Mammography is associated with variable, not descriptive findings and it is often not diagnostic. We planned to address the role of Magnetic Resonance Imaging (MRI) of the breast in women with newly diagnosed IBC.&amp;#x2028; MATERIALS AND METHODS:&amp;#x2028; We performed a retrospective analysis of newly diagnosed IBC cases evaluated at the University of Texas. M D Anderson Cancer Center between December 2003 and February 2008. Baseline breast MRI exams were performed on 1.5-Tesla (T) or 3.0-T GE scanners and included dynamic three-dimensional T1-weighted fast spoiled gradient echo sequences with parallel imaging after a bolus injection of gadolinium based IV contrast. Exams were reviewed in batches and the findings rated in accordance with the ACR BI-RADS MRI Lexicon. The following parameters were evaluated; presence and characteristics of breast masses and skin description. All patients had concomitant mammograms and ultrasound exams.&amp;#x2028; RESULTS: &amp;#x2028; Eighty women with a clinical diagnosis of IBC were included in the study with a median age of 52 years, (range, 25 to 78). MRI detected a primary breast lesion in 80 of 82 symptomatic breasts (98%), compared to only 53 of 78 (68%) with mammogram (p &amp;lt; 0.0001). The most common MRI morphologic characteristic of the lesions was irregular margins (72%) with heterogeneous internal enhancement (82%). Qualitative evaluation of the enhancement pattern demonstrated wash-out in 85% of the cases.&amp;#x2028; MRI detected skin thickening in 90% of the patients (average skin thickness of 8 mm [range, 4-17 mm]), compared to 69% with mammogram. Heterogeneous skin enhancement (82%) and nodular or irregular skin lesions (43%) were identified only with MRI. These skin lesions demonstrated a progressive enhancing pattern, in contrast to the rapid wash-out pattern expected for malignant breast lesion.&amp;#x2028; CONCLUSIONS: &amp;#x2028; This study establishes breast MRI as the most sensitive and accurate imaging modality in assessing the breast of IBC patients. The most common radiological features are represented by the presence of a primary breast lesion and global skin thickening with heterogeneous skin enhancement. The combination of morphology and enhancing pattern may provide information to understand the biology of this disease and accurately monitor residual disease during neoadjuvant therapies. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4008.

Dose comparison of single versus double dose in contrast-enhanced magnetic resonance angiography of the renal arteries: intra-individual cross-over blinded trial using Gd-DTPA

This study was planned as an open-label, single-centre trial with blinded evaluations by two independent radiologists, aimed at the intra-individual comparison of single-dose and double-dose Gd-DTPA-enhanced MRA in the renal arterial territory. Ten healthy volunteers were included in the study. Renal MRAs were carried out on a clinical 1.5-T MR system using a body phased-array coil. Images were acquired with three-dimensional fast spoiled gradient echo sequence. Contrast agent was injected with a power injector keeping the injection time constant for single dose and double dose. Both readers found at least 96% of vascular segments evaluable. Median overall image quality was rated excellent, and diagnostic confidence was rated confident. No statistically significant difference between the dosage groups could be demonstrated. Signal intensity, SNR and CNR were significantly higher for the double-dose group. Our results demonstrate that while a double dose of contrast agent increases SNR, it does not lead to further improvement in visual and perceptual image quality. A single dosage of approximately 0.1 mmol/kg bw Gd-DTPA may be the preferable dosage to demonstrate the renal arteries.

Detection of brain metastasis at 3T: comparison among SE, IR-FSE and 3D-GRE sequences

The objective of this study is to compare the detectability of brain metastases at 3T among three contrast-enhanced sequences, spin-echo (SE) sequence, inversion recovery fast SE (IR-FSE) sequence (both with section thickness of 6 mm), and three-dimensional fast spoiled gradient-echo (3D fast SPGR) sequence with 1.4 mm isotropic voxel. First, phantom studies were performed to quantify the contrast-enhancement ratio (CER) with three sequences. In 21 consecutive patients with brain metastases, axial images of three sequences at 3T were obtained after administration of gadoteridol. Two neuroradiologists assessed the detectability of brain metastases for the three sequences. In the phantom study, no evident difference in the CER was demonstrated among three sequences. Significantly more brain metastases were detected with 3D fast SPGR than with SE and IR-FSE (a total of 97 lesions with 3D fast SPGR vs. 64 with SE and 63 with IR-FSE). In particular, 3D fast SPGR was superior to the other two sequences in detection of the small lesions (<3 mm). At 3T, the contrast-enhanced 3D fast SPGR with 1.4 mm isotropic voxel is clinically more valuable for detecting small brain metastases than the SE and IR-FSE with section thickness of 6 mm.

Colorectal neoplasm: Magnetic resonance colonography with fat enema-initial clinical experience

To assess Magnetic resonance colonography with fat enema as a method for detection of colorectal neoplasm. Consecutive twenty-two patients underwent MR colonography with fat enema before colonoscopy. T1-weighted three-dimensional fast spoiled gradient-echo with inversion recovery sequence was acquired with the patient in the supine position before and 75 s after Gadopentetate Dimelumine administration. Where by, pre and post MR coronal images were obtained with a single breath hold for about 20 s to cover the entire colon. The quality of MR colonographs and patients' tolerance to fat contrast medium was investigated. Colorectal neoplasms identified by MR colonography were compared with those identified on colonoscopy and sensitivity of detecting the lesions was calculated accordingly. MR colonography with fat enema was well tolerated without sedation and analgesia. 120 out of 132 (90.9%) colonic segments were well distended and only 1 (0.8%) colonic segment was poor distension. After contrast enhancement scan, mean contrast-to-noise ratio (CNR) value between the normal colonic wall and lumen was 18.5 +/- 2.9 while mean CNR value between colorectal neoplasm and lumen was 20.2 +/- 3.1. By Magnetic resonance colonography, 26 of 35 neoplasms (sensitivity 74.3%) were detected. However, sensitivity of MRC was 95.5% (21 of 22) for neoplasm larger than 10 mm and 55.6% (5 of 9) for 5-10 mm neoplasm. MR colonography with fat enema and T1-weighted three-dimensional fast spoiled gradient-echo with inversion recovery sequence is feasible in detecting colorectal neoplasm larger than 10 mm.

Indirect MR lymphangiography of the head and neck using conventional gadolinium contrast: A pilot study in humans

To evaluate indirect magnetic resonance lymphangiography (MR-LAG) using interstitial injection of conventional gadolinium contrast (gadoteridol and gadopentetate dimeglumine) for delineating the primary lymphatic drainage of head-and-neck sites. We performed head-and-neck MR-LAG in 5 healthy volunteers, with injection of dermal and mucosal sites. We evaluated the safety of the procedure, the patterns of enhancement categorized by injection site and nodal level, the time course of enhancement, the optimal concentration and volume of contrast, and the optimal imaging sequence. The worst side effects of interstitial contrast injection were brief, mild pain and swelling at the injected sites that were self-limited. MR-LAG resulted in consistent visualization of the primary lymphatic drainage pattern specific to each injected site, which was reproducible on repeated examinations. The best enhancement was obtained with injection of small volumes (0.3-0.5 mL) of either agent diluted, imaging within 5-15 min of injection, and a three-dimensional fast spoiled gradient echo sequence with magnetization transfer. We found head-and-neck MR-LAG to be a safe, convenient imaging method that provides functional information about the lymphatic drainage of injected sites. Applied to head-and-neck cancer, it has the potential to identify sites at highest risk of occult metastatic spread for radiotherapy or surgical planning, and possibly to visualize micrometastases.

Assessment of Crohn’s disease in the small bowel: prospective comparison of magnetic resonance enteroclysis with conventional enteroclysis

Our objective was to assess the diagnostic value of magnetic resonance enteroclysis (MRE) compared with conventional enteroclysis (CE) in patients with Crohn's disease. A secondary objective was to evaluate the diagnostic accuracy of each different MR sequence. Sixty-six consecutive patients with known Crohn's disease underwent MRE and CE. Fast imaging employing steady-state acquisition (FIESTA), single-shot fast spin-echo (ssFSE), and contrast-enhanced T1-weighted sequences were assessed by two radiologists who reached a consensus about the following findings: visualization of wall ulcers, pseudopolyps, fistulae, mural stenosis, and mesenteric abnormalities. Standard descriptive statistics and the McNemar test were used. The sensitivity, specificity and accuracy of MRE were 90-87% and 83% for the depiction of parietal ulcers, 84%-88% and 86% for pseudopolyps, 100-94% and 96% for mural stenosis, 93-100% and 94% for fistulae. The number of detected extraluminal findings was significantly higher with MRE (P < 0.01). The accuracy of FIESTA sequence was statistically higher in the depiction of wall ulcers and fistulae than that of three-dimensional fast spoiled gradient echo (3D-FSPGR) (P < 0.01) and ssFSE (P < 0.05) sequences. Contrast-enhanced 3D-FSPGR was superior for mural stenosis visualization compared to ssFSE (P < 0.05) and FIESTA (P < 0.05). MRE correlates accurately with CE in the detection of superficial and transmural abnormalities and has the advantage of assessing the mesenteric manifestations.

Estudio no invasivo de las venas cerebrales y los senos durales: comparación de dos técnicas de angiografía con resonancia magnética

To evaluate MR venography with bolus injection of intravenous contrast and elliptical filling of the K space, using three-dimensional fast spoiled gradient-echo (3D-FSPGR) sequences, and to compare it to the technique most frequently employed in the study of cerebral veins and dural sinuses, which is two-dimensional time-of-flight (2D-TOF) MR venography. Source images, multiplanar reconstructions, and maximum intensity projections (MIP) were obtained using both 2D-TOF venography and contrasted-enhanced 3D-FSPGR venography in 20 healthy volunteers. Two radiologists independently evaluated both techniques for the visualization of twenty-one predefined venous structures, classifying the depiction as completely visible, partially visible, or not visible. The predefined venous structures were completely visible in 795 of 840 (94.6%) of the evaluations of contrast-enhanced 3D-FSPGR images versus 682 of 840 (81.1%) evaluations of 2D-TOF venography images. In the major dural sinuses, visualization was complete in 99.4% of the readings of contrast-enhanced 3D-FSPGR images versus 81% in the readings of the 2D-TOF images. 3D-FSPGR with elliptical filling of the K space and bolus injection of contrast material provides higher quality images of the intracranial venous system than those obtained using 2D-TOF sequences.

Three-Dimensional Demonstration of the Artery of Adamkiewicz With Contrast-Enhanced Magnetic Resonance Angiography

An ascending aortic graft replacement for a Stanford type A aortic dissection was performed on a 58-year-old male. One year later the diameter of the descending aorta reached 60 mm. He was again hospitalized for a second descending aortic replacement. For preoperative assessment a contrast-enhanced magnetic resonance angiography (MRA) was requested in order to determine the level of the artery of Adamkiewicz (AdA) which supplies the anterior spinal artery. A three-dimensional (3D) fast-spoiled gradient-echo (fast-SPGR) technique with fat suppression using a 1.5T superconducting imager (Signa, GE Medical Systems, Milwaukee, WI) was applied with the voxel size being 0.50 × 0.47 × 0.44 mm. Fifteen milliliters of Gd-DTPA (Magnevist, Shering, Berlin, Germany) were injected into the antecubital vein. All the scanned data were transferred to a workstation (ZIO-M900, ZIOsoft, Tokyo, Japan). Multiplanar reconstruction (MPR), maximum intensity projections (MIP), and 3D volume rendering techniques were applied. The oblique coronal MPR image (Fig 1; T10 = tenth thoracic vertebra) illustrates the AdA (arrow) and the posterior branch of the tenth intercostal artery (arrowhead). An axial partial MIP image (Fig 2) illustrates the left tenth intercostal artery (arrow) originating from the false lumen (F) and the right tenth intercostal artery originating from the true lumen (T). A thirty-degree right anterior oblique 3D volume rendering image was obtained (Fig 3 ; the true lumen: red, the false lumen: blue, AdA and anterior spinal artery: purple). This image clearly demonstrated the continuity between the left tenth intercostal artery which originated from the false lumen and the anterior spinal artery. The detection rate of AdA in chronic dissection is 50% by MRA. Selective intercostal and lumbar arteriography was undertaken to depict preoperative anatomy although it was not indicated in the patient with a dissecting aortic aneurysm. MRA may better depict the AdA clearly and provide valuable information for surgical management.Fig 2View Large Image Figure ViewerDownload (PPT)Fig 3View Large Image Figure ViewerDownload (PPT)