T2-weighted Turbo Spin-echo Magnetic Resonance Research Articles

T2-weighted turbo spin-echo magnetic resonance imaging of canine brain anatomy at 1.5T, 3T, and 7T field strengths.

Post-mortem T2 weighted images of canine heads were acquired at 1.5T, 3T, and 7T. This study aimed to (1) identify anatomical structures of the canine brain using an ultra-high-field magnetic resonance imaging (MRI) (7T) to help to facilitate their localization on high field MRI images (3T and 1.5T), where these structures may appear less well defined and delineated and (2) evaluate the visibility of canine brain anatomical structures on 1.5T, 3T, and 7T MRI images for optimizing clinical utility. Our hypothesis was that the provided subjective image quality comparison at different field strengths may offer a general baseline for canine brain anatomy and may help clinicians evaluate MRI options better. Six canine heads were examined with 1.5T, 3T, and 7T MRI scanners. T2-weighted images were acquired in three orthogonal planes at each field strength using a turbo spin-echo sequence. Fifty neuroanatomic structures were identified and evaluated on the 7T MR images; subsequently, those were found on the 3T and 45 out of the 50 structures were detected on the 1.5T imaging. The structures that were not able to be identified on the 1.5T imaging included the septum pellucidum, oculomotor nucleus, substantia nigra, claustrum, and thalamic nucleus griseus. Images acquired at 7T were subjective of higher spatial and contrast resolution. However, the ultra-high-field images were prone to artifacts at the interface between tissues of different magnetic properties. In conclusion, 3T MR imaging appears to be the best comprise for evaluating canine brain anatomy on MRI with fewer imaging artifacts.

MRI of the cervical spine with 3D gradient echo sequence at 3 T: initial experience

The aim of this study was to compare three-dimensional (3D) high resolution T2*-weighted gradient echo (3D FFE) magnetic resonance (MR) sequence with conventional 2D T2-weighted turbo spin echo (TSE) MR sequence for imaging of the cervical spine, especially to assess the detectability of the internal anatomy of the cervical spinal cord, i.e. to distinguish the grey and white matter. Fifteen volunteers were examined at 3.0T MR unit. Signal-to-noise (SNR), contrast-to-noise (CNR) and image homogeneity were evaluated. In the visual analysis, the visibility of anatomical structures of the cervical spine and artifacts were assessed. The nonparametric method of paired sample t-test was adopted to evaluate the differences between the sequences. The 3D FFE sequence provided better results for CNR, cerebrospinal fluid (CSF) versus white matter, grey matter, disk and bone. Moreover, it yielded good results for the CNR grey matter versus white matter. The butterfly-shaped "H" is clearly displayed in the 3D FFE sequence. The statistical analysis revealed the statistically significant difference between the 2D TSE and 3D FFE sequences for the contrast of CSF versus spinal cord (both grey matter and white matter). The 3D FFE sequence in MR imaging of the cervical spinal cord is superior in delineation of spinal cord anatomical structures compared to 2D TSE sequence.

Localized Hyperthermia with Iron Oxide–Doped Yttrium Microparticles: Steps toward Image-Guided Thermoradiotherapy in Liver Cancer

PurposeTo test whether iron oxide (IO)–containing yttrium aluminosilicate (YAS) microparticles (MPs) can generate localized therapeutic hyperthermia (≥ 43°C) when injected intratumorally in an animal model of liver cancer and whether MP distributions could be visualized with magnetic resonance (MR) imaging. Materials and MethodsTwenty-one Sprague–Dawley rats implanted with N1-S1 liver tumors were assigned to alternating magnetic field (AMF) exposure following intratumoral injection with IO-YAS MPs (n = 7), sham surgery (n = 7), or baseline iron quantification (n = 7). Three fiberoptic probes allowed spatial and temporal monitoring of temperatures during 24 minutes of AMF exposure. T2-weighted turbo spin-echo MR imaging was performed within 1 hour after the procedure to detect signal voids caused by IO-YAS deposition. Hematoxylin and eosin–stained pathologic slides were also obtained, and the presence of IO-YAS was evaluated with inductively coupled plasma optical emission spectroscopy. ResultsFollowing AMF exposure, intratumoral temperatures after IO-YAS MP injection achieved therapeutic hyperthermia whereas those after sham surgery did not (46.6°C ± 1.3 vs 36.8°C ± 0.4; P < .0001). Within the treated group, the normal hepatic parenchyma (NHP) and rectal temperatures were 37.4°C ± 0.9 and 36.5°C ± 1.0 (P = .0809) at the conclusion of AMF exposure, respectively. A T2-weighted signal void at the tumor site was observed in all seven treated animals, and intratumoral IO-YAS was visualized on subsequent histopathologic examination in each case. The mean ratio of tumor:NHP Fe concentrations attributable to IO-YAS MPs was 108:1. ConclusionsAMF exposure of intratumoral IO-YAS MPs generates localized therapeutic hyperthermia in an animal model of liver cancer. MR detectability and potential for combination brachytherapy warrants further investigation for thermoradiotherapy in liver cancer.

Endometrial cancer: preoperative staging using three-dimensional T2-weighted turbo spin-echo and diffusion-weighted MR imaging at 3.0 T: a prospective comparative study

To prospectively assess the efficacy of 3-T magnetic resonance (MR) imaging using the three-dimensional turbo spin-echo T2-weighted and diffusion-weighted technique (3D-TSE/DW) compared with that of conventional imaging using the two-dimensional turbo spin-echo T2-weighted and dynamic contrast-enhanced technique (2D-TSE/DCE) for the preoperative staging of endometrial cancer, with pathological analysis as the reference standard. Seventy-one women with endometrial cancer underwent MR imaging using 3D-TSE/DW (b = 1,000s/mm(2)) and 2D-TSE/DCE. Two radiologists independently assessed the two imaging sets. Accuracy, sensitivity, and specificity for staging were analysed with the McNemar test; the areas under the receiver operating characteristic curve (Az) were compared with a univariate z-score test. The results for assessing deep myometrial invasion, accuracy, sensitivity, specificity and Az, respectively, were as follows: 3D-TSE/DW-observer 1, 87%, 95%, 85% and 0.96; observer 2, 92%, 84%, 94% and 0.95; 2D-TSE/DCE-observer 1, 80%, 79%, 81% and 0.89; observer 2, 86%, 84%, 87% and 0.86. Most of the values were higher with 3D-TSE/DW without significant differences (P > 0.12). For assessing cervical stromal invasion, there were no significant differences in those values for both observers (P > 0.6). Accuracy of 3D-TSE/DW was at least equivalent to that of the conventional technique for the preoperative assessment of endometrial cancer. • New techniques in MR imaging help assess patients with endometrial cancer. • A 3D T2-weighted TSE sequence seems equally as accurate as conventional techniques. • Three-dimensional TSE/DW imaging does not require intravenous contrast material and is relatively quick. • Tumour extent of endometrial cancer can be clearly shown on diffusion-weighted images. • Junctional zone can be visualised well on 3D-TSE T2-weighted images.

Uterine Tumors: Comparison of 3D versus 2D T2-weighted Turbo Spin-Echo MR Imaging at 3.0 T—Initial Experience

To compare a three-dimensional (3D) T2-weighted turbo spin-echo (TSE) magnetic resonance (MR) sequence (VISTA; Philips Medical Systems, Best, the Netherlands) with a two-dimensional (2D) T2-weighted TSE sequence in terms of image quality, signal intensity (SI) difference ratios, conspicuity, and staging of uterine tumors. This retrospective study was approved by the institutional review board, and informed consent was waived. Sixty-one women (mean age, 53.0 years ± 13.7 [standard deviation]; range, 30-87 years) with cervical carcinoma (n = 28), endometrial carcinoma (n = 21), or leiomyoma (n = 30) of the uterus were included. Patients underwent T2-weighted MR imaging at 3 T with both 1-mm-thick 3D and 5-mm-thick 2D T2-weighted TSE sequences. Three-dimensional T2-weighted TSE images were reconstructed at 5-mm thickness with the aid of a workstation. Quantitative analyses of signal-to-noise ratio (SNR) and SI difference ratios between tumors and other tissues and qualitative analyses of image quality and tissue conspicuity were performed. Two radiologists independently assessed local-regional staging for carcinomas. Quantitative values, qualitative scores, and tumor staging were analyzed by using the paired t test, Wilcoxon signed rank test, and McNemar test, respectively. Mean myometrial SNR was higher on 3D than 2D images (14.3 vs 9.8; P < .0001). Mean SI difference ratios between cervical (0.45 vs 0.34; P < .0001) or endometrial (0.46 vs 0.40; P = .044) carcinomas and gluteal muscle were higher on 3D images, but those between leiomyoma and myometrium (0.33 vs 0.43; P < .0001) were lower than those on 2D images. Image quality (P = .0004) and carcinoma conspicuity (P < .0005) were superior with the 3D T2-weighted TSE sequence. Although multiplanar reconstruction of 3D T2-weighted TSE images was useful for staging in one case, there were no significant differences between 3D and 2D T2-weighted TSE imaging in accuracy of staging for the two readers for cervical or endometrial carcinoma. The 3D T2-weighted TSE sequence showed certain advantages over the 2D T2-weighted TSE sequence, and it has the potential to improve the performance of MR imaging for the evaluation of uterine carcinoma.

Radiologic and Pathologic Findings in Breast Tumors with High Signal Intensity on T2-weighted MR Images

Various histopathologic components in benign and malignant breast lesions may generate hyperintense signal at T2-weighted magnetic resonance (MR) imaging. A comparison of the specific histologic features found in breast lesions with a high-signal-intensity appearance on unenhanced T2-weighted turbo spin-echo MR images obtained without spectral fat suppression shows that this MR imaging characteristic is often suggestive of the differential diagnosis. Histopathologic features that may produce high signal intensity in breast lesions include extensive necrosis, a cystic or microcystic component, an adipose or sebaceous component, mucinous stroma, loose myxoid stroma, stromal edema, and hemorrhagic changes. A more nuanced understanding of the correlation between the MR imaging appearance and specific pathologic findings may help radiologists achieve earlier and more accurate differentiation among this group of breast lesions.

Biliary anatomy on 3D MRCP: Comparison of volume-rendering and maximum-intensity-projection algorithms

To compare volume-rendering (VR) and maximum-intensity-projection (MIP) of three-dimensional T2-weighted turbo spin-echo magnetic resonance cholangiopancreatography using a free-breathing navigator-triggered prospective acquisition correction (3D-TSE-PACE-MRCP) to define biliary anatomies. VR and MIP images of 3D-TSE-PACE-MRCP for 102 patients were retrospectively evaluated. Interpretation of cystic duct variation and biliary branching patterns of each image were recorded independently by two radiologists in a blinded fashion. Interpretation confidence on a five-point scale was compared using the Wilcoxon signed-rank test. The McNemar test was used to compare the accuracies of each reformation with the reference standard obtained by consensus interpretation of both the images and source images. The reference standard identified all biliary bifurcations and 95 of 102 cystic duct confluences (93.1%). VR findings agreed with the reference standard findings more often than MIP with regard to cystic duct variation (94 [92.2%] vs. 76 [74.5%], P<0.01) while there was no significant difference for biliary branching patterns (99 [97.1%] vs. 92 [90.2%], P=0.092). The mean confidence score was significantly higher with VR than MIP with regard to both cystic duct variation and biliary branching patterns (3.7 vs. 2.4; P<0.01; 4.1 vs. 3.3; P<0.01). VR reformation of 3D-TSE-PACE-MRCP defines biliary anatomies more accurately than MIP.

MRCP vs ERCP in the evaluation of biliary pathologies: Review of current literature

Recently developed magnetic resonance (MR) techniques permit fast and correct imaging of the entire biliary tree with a high spatial resolution. The aim of this study was to compare the diagnostic potential of one of these new MR sequences in magnetic resonance cholangiopancreatography (MRCP) procedure and endoscopic retrograde cholangiopancreatography (ERCP) with review of current literatures. A total of 295 patients were enrolled in this study prospectively. Of these, 11 were excluded from the study due to inadequate MRCP image quality and 15 more were excluded due to unsuccessful cannulation during ERCP. Thus, finally 269 patients (124 men and 145 women with a mean age of 57 years; range: 23-92 years) were included. The MRCP procedure was performed before the ERCP in all cases. All MRCP studies were performed with recently developed new MR technique using a heavily T2-weighted turbo spin echo (TSE) sequence. This TSE sequence is currently one of the most widely used multiplanar 3-D MR technique, having a high spatial resolution and fast imaging capacity. The study participants were classified into four main groups; normal into group I, stone disease into group II, tumor into group III and others into group IV. Group I consisted of 228 patients who had a normal pancreaticobiliary tree on both the MRCP and ERCP examinations. In group II there were 18 patients, for whom the MRCP had a 88.9% sensitivity and a 100% specificity for diagnosing biliary stone disease. Its positive predictive value (PPV), negative predictive value (NPV) and accuracy rates were 100%, 99.2% and 99.2%, respectively. The MRCP had a 100% sensitivity and a 100% specificity for 20 patients in group III. It also had 100% PPV, 100% NPV, and 100% total accuracy rates in this group. In three patients in group IV, the MRCP had a 100% sensitivity and specificity, respectively. Its PPV, NPV and accuracy were 100%, 100% and 100%, respectively. MRCP is used with increasing frequency as a non-invasive alternative to ERCP and the diagnostic results of MRCP with a heavily T2-weighted TSE MR sequence and ERCP are comparable with high accuracy in various hepatobiliary pathologies.

Abstract No. 161: Comparison of Hypoxia Inducible Factor-1 alpha Expression before and after TAE in Rabbit VX2 Liver Tumors

Abstract No. 161: Comparison of Hypoxia Inducible Factor-1 alpha Expression before and after TAE in Rabbit VX2 Liver Tumors

Effect of Transcatheter Arterial Embolization on Levels of Hypoxia-inducible Factor-1α in Rabbit VX2 Liver Tumors

To test the hypothesis that transcatheter arterial embolization (TAE) of VX2 rabbit liver tumors increases the expression of hypoxia-inducible factor-1alpha (HIF-1alpha), a transcription factor that regulates the expression of pro-angiogenic genes. VX2 tumors were implanted in the livers of eight New Zealand white rabbits. Once tumor growth was seen at T2-weighted turbo spin-echo magnetic resonance (MR) imaging, four of the eight rabbits underwent TAE with 45-150-mum polyvinyl alcohol particles. The remaining four rabbits served as non-TAE controls. The TAE end point was stasis of antegrade blood flow. All rabbits were sacrificed for tumor harvest 2 hours after TAE. Tumor tissue and corresponding normal liver tissue in each rabbit liver were stained with anti-human HIF-1alpha monoclonal antibody and reviewed with light microscopy. Percentages of stained viable tumor and normal liver cells were compared by using the Mann-Whitney U test (alpha=0.05). In eight rabbits with 24 discrete liver tumors, the mean percentage (+/-standard deviation) of positive HIF-1alpha-stained cells in the TAE group was greater than that in the control group (19%+/-7.0 vs 12%+/-8.0, respectively) (P=.05). Normal liver tissue in both the TAE and control groups showed no HIF-1alpha staining. Although HIF-1alpha is not expressed in normal rabbit liver parenchyma-even after TAE-HIF-1alpha expression is present in implanted VX2 rabbit liver tumors and significantly increased in lesions that have undergone embolization.

Female Pelvis: MR Imaging at 3.0 T with Sensitivity Encoding and Flip-Angle Sweep Technique

This study had institutional review board approval; all 33 patients (mean age, 47 years +/- 16 [standard deviation]) gave informed consent. The aim was to prospectively evaluate the diagnostic image quality yielded by a 3.0-T T2-weighted turbo spin-echo magnetic resonance imaging sequence with a very short imaging time versus that yielded by a standard 3.0-T sequence at imaging of the female pelvis. Signal-to-noise ratio and delineation of gynecologic disorders were approximately equal between the two sequences. The majority of tissue contrasts were comparable, but contrast between fluid and muscle was significantly higher and motion artifacts were reduced (P < .001 for both) with the short imaging time sequence. The fast sequence maintained or improved image quality and thus seems to be advantageous for uncooperative patients.

Focal Liver Lesions: SPIO-, Gadolinium-, and Ferucarbotran-enhanced Dynamic T1-weighted and Delayed T2-weighted MR Imaging in Rabbits

To compare a superparamagnetic iron oxide (SPIO), VSOP-C184, with a gadopentetate dimeglumine with regard to signal-enhancing effects on T1-weighted dynamic magnetic resonance (MR) images and with another SPIO contrast medium with regard to signal-reducing effects on delayed T2-weighted MR images. All experiments were approved by the responsible Animal Care Committee. Twenty rabbits (five for each contrast agent and dose) implanted with VX-2 carcinoma were imaged at 1.5 T. VSOP-C184 at 0.015 and 0.025 mmol Fe/kg was compared with gadopentetate dimeglumine at 0.15 mmol Gd/kg and ferucarbotran at 0.015 mmol Fe/kg. The imaging protocol comprised a T1-weighted dynamic gradient-echo (GRE) MR before injection and at 6-second intervals for up to 42 seconds after injection and a T2-weighted turbo spin-echo MR before and 5 minutes after injection. Images were evaluated quantitatively, and contrast media were compared by using nonparametric analysis of variance. At dynamic T1-weighted GRE MR imaging with 0.015-mmol Fe/kg VSOP-C184, 0.025-mmol Fe/kg VSOP-C184, gadopentetate dimeglumine, and ferucarbotran, the median peak contrast-to-noise ratio (CNR) was 20.7 (25th percentile, 16.3; 75th percentile, 22.6), 24.2 (25th percentile, 19.3; 75th percentile, 28.5), 16.4 (25th percentile, 13.7; 75th percentile, 20.3), and 14.0 (25th percentile, 11.4; 75th percentile, 16.8), respectively. Both doses of VSOP-C184 yielded significantly higher CNR (P < .05) than the other two agents. At T2-weighted turbo spin-echo imaging with 0.015-mmol Fe/kg VSOP-C184, 0.025-mmol Fe/kg VSOP-C184, gadopentetate dimeglumine, and ferucarbotran, the median CNR was 15.0 (25th percentile, 13.4; 75th percentile, 21.3), 15.7 (25th percentile, 14.5; 75th percentile, 19.8), 11.3 (25th percentile, 8.2; 75th percentile, 12.2), and 15.7 (25th percentile, 12.5; 75th percentile, 22.4), respectively. There was no significant difference between VSOP-C184 and ferucarbotran; both had a significantly higher CNR than did gadopentetate dimeglumine. VSOP-C184 produces higher liver-to-tumor contrast at dynamic T1-weighted imaging than does gadopentetate dimeglumine; at delayed T2-weighted imaging, the contrast is comparable to that achieved with ferucarbotran.

Rectal Cancer: MR Imaging in Local Staging—Is Gadolinium-based Contrast Material Helpful?

To determine retrospectively whether addition of gadolinium-enhanced T1-weighted magnetic resonance (MR) sequence to T2-weighted turbo spin-echo (SE) MR imaging is valuable for preoperative assessment of T stage and circumferential resection margin in patients with primary rectal cancer. Local institutional review board approved study and waived informed patient consent. Eighty-three patients with operable primary rectal cancer underwent preoperative MR imaging. Retrospectively, two observers independently scored T2-weighted turbo SE MR images and, in a second reading, T2-weighted images combined with gadolinium-enhanced T1-weighted turbo SE MR images for tumor penetration through rectal wall and tumor extension into mesorectal fascia. A confidence level scoring system was used, and receiver operating characteristic (ROC) curves were generated. Histologic findings were standard of reference. Difference in performance of T2-weighted and combined T2-weighted plus gadolinium-enhanced T1-weighted sequences was analyzed by comparing corresponding areas under ROC curves (A(z)) for each observer. Interobserver agreement was calculated by using linear weighted kappa statistics. Addition of contrast-enhanced T1-weighted to T2-weighted MR imaging did not significantly improve diagnostic accuracy for prediction of tumor penetration through rectal wall (A(z) of T2-weighted vs T2-weighted plus T1-weighted images for observer 1, 0.740 vs 0.764; observer 2, 0.856 vs 0.768) and tumor extension into mesorectal fascia (A(z) for observer 1, 0.962 vs 0.902; observer 2, 0.902 vs 0.911). Diagnostic performance (A(z)) of MR and interobserver agreement were high for prediction of tumor extension into mesorectal fascia (kappa = 0.61, 0.74) but only moderate for penetration through rectal wall (kappa = 0.47, 0.45). Gadolinium-enhanced MR sequences did not improve diagnostic accuracy for assessment of tumor penetration through rectal wall and tumor extension into mesorectal fascia.

Characterization of focal liver lesions with superparamagnetic iron oxide-enhanced MR imaging: value of distributional phase T1-weighted imaging.

ObjectiveTo determine the potential value of distributional-phase T1-weighted ferumoxides-enhanced magnetic resonance (MR) imaging for tissue characterization of focal liver lesions.Materials and MethodsFerumoxides-enhanced MR imaging was performed using a 1.5-T system in 46 patients referred for evaluation of known or suspected hepatic malignancies. Seventy-three focal liver lesions (30 hepatocellular carcinomas [HCC], 12 metastases, 15 cysts, 13 hemangiomas, and three cholangiocarcinomas) were evaluated. MR imaging included T1-weighted double-echo gradient-echo (TR/TE: 150/4.2 and 2.1 msec), T2*-weighted gradient-echo (TR/TE: 180/12 msec), and T2-weighted turbo spin-echo MR imaging at 1.5 T before and after intravenous administration of ferumoxides (15 mmol/kg body weight). Postcontrast T1-weighted imaging was performed within eight minutes of infusion of the contrast medium (distributional phase). Both qualitative and quantitative analysis was performed.ResultsDuring the distributional phase after infusion of ferumoxides, unique enhancement patterns of focal liver lesions were observed for hemangiomas, metastases, and hepatocellular carcinomas. On T1-weighted GRE images obtained during the distributional phase, hemangiomas showed a typical positive enhancement pattern of increased signal; metastases showed ring enhancement; and hepatocellar carcinomas showed slight enhancement. Quantitatively, the signal-to-noise ratio of hemangiomas was much higher than that of other tumors (p < .05) and was similar to that of intrahepatic vessels. This finding permitted more effective differentiation between hemangiomas and other malignant tumors.ConclusionT1-weighted double-echo FLASH images obtained soon after the infusion of ferumoxides, show characteristic enhancement patterns and improved the differentiation of focal liver lesions.

Incidence of adrenal masses in patients referred for renal artery stenosis screening MR.

Prior work has shown the efficacy of magnetic resonance (MR) in renal artery stenosis evaluation. The increasing role of renal artery stenosis in the differential diagnostic evaluation of hypertension raises the question of whether MR should be used as a screening modality. This project evaluated the additional potential benefits of MR by determining the incidence of adrenal masses in this selected population. A 2-year retrospective study analysis of patients who failed to respond to antihypertensive medical management and were referred for renal MR for hypertension amassed 77 subjects ranging in age from 18 to 88 years. A masked analysis for adrenal masses was performed on this data set. Magnetic resonance techniques included T2-weighted turbo spin-echo (repetition time [TR] 2000-4000 ms, echo time [TE] 80-100 ms, turbo factor 2-16), T1-weighted spin-echo (TR 200-500 ms, TE 10-30 ms), gradient-echo time-of-flight (TR 26 ms, TE 6.9 ms, 40 degrees flip angle, 2 excitations), and dynamic gadopentetate dimeglumine-enhanced MR angiography (three-dimensional gradient recalled echo, TR 10 ms, TE 3 ms, 40 degrees flip angle, 1 excitation). Thirty-three patients had renal artery disease, 44 had normal renal arteries, and 7 had adrenal masses. Forty-three percent of patients who underwent renal MR had disease of the renal arteries detected, and 9% of patients referred for MR had adrenal masses that would have been missed with scintigraphy and/or angiography, of which 57% were responsible for hypertension. The ability to evaluate renal artery and adrenal anatomy globally can be useful, as exemplified in the current series, and the adrenals should be examined carefully in any renal MR in a hypertensive patient.

Hepatocellular carcinoma and dysplastic nodules in patients with cirrhosis: prospective diagnosis with MR imaging and explantation correlation.

To determine the sensitivity and specificity of magnetic resonance (MR) imaging for detection of hepatocellular carcinoma (HCC) and dysplastic nodules (DNs) by using explantation correlation in patients with cirrhosis and no known HCC. Seventy-one patients without a known history of HCC who underwent MR imaging and subsequent transplantation within 90 days were examined. Breath-hold turbo short inversion time inversion-recovery and/or T2-weighted turbo spin-echo MR images were obtained. Dynamic two- or three-dimensional gadolinium-enhanced gradient-echo MR images were obtained in the hepatic arterial, portal venous, and equilibrium phases. Prospective MR image interpretations were compared directly with explanted liver pathologic results. Eleven (15%) of 71 patients had hepatic malignancies; MR imaging enabled diagnosis of tumor in six (54%) of 11 patients. On a lesion-by-lesion basis, MR imaging depicted 11 of 20 hepatic neoplasms, for an overall sensitivity of 55%. MR imaging depicted four (80%) of five lesions larger than 2 cm, six (50%) of 12 lesions 1-2 cm, and one (33%) of three lesions smaller than 1 cm. MR imaging depicted only nine (15%) of 59 DNS: The specificities of MR imaging for detection of HCC and DNs on a per patient basis were 60 (86%) of 70 patients and 53 (85%) of 62 patients, respectively. MR imaging is insensitive for the diagnosis of small (<2-cm) HCCs and DNS:

Endoluminal MR imaging of the rectum and anus: technique, applications, and pitfalls.

Anorectal diseases (e.g., fecal incontinence, perianal and anovaginal fistulas, anorectal tumors) require imaging for proper case management. Endoluminal magnetic resonance (MR) imaging has become an important part of diagnostic work-up in such cases. Optimal endoluminal MR imaging requires careful attention to patient preparation, imaging protocols, and potential pitfalls in interpretation. Comfortable positioning and the use of an antiperistaltic drug are vital for adequate patient preparation. Selected sequences and imaging planes are used in imaging protocols tailored for specific diseases. In fecal incontinence, three-dimensional sequences allow detailed demonstration of the anal anatomy and related defects. In perianal and anovaginal fistulas, longitudinal imaging planes help determine the superior extent of the abnormality. In anorectal tumors, T1-weighted turbo spin-echo MR imaging can help detect extension into the perirectal fat and T2-weighted turbo spin-echo MR imaging is used to optimize contrast between tumor and the rectal wall. Off-axis and radial imaging planes are used in all anorectal diseases to minimize partial volume effects. Potential pitfalls include various parts of the normal anal anatomy mimicking sphincter defects, veins and hemorrhoids mimicking fistulas and abscesses, and overhanging tumor mimicking more extensive tumor. Adequate patient preparation combined with proper technique and a knowledge of potential pitfalls will allow optimal endoluminal MR imaging of the rectum and anus.

Fast dynamic contrast enhanced mr imaging of cervical carcinoma

The first pass phase of contrast material is most important to study vascularization and perfusion of tissue and can be studied using dynamic magnetic resonance (MR) imaging. The purpose of this prospective study was to evaluate the usefulness of pre-contrast vs. post-contrast and fast dynamic MR imaging in the preoperative staging of cervical carcinomas. To assess the normal onset of enhancement of the uterus and cervix 15 volunteers underwent dynamic MR imaging. Forty-two consecutive patients with invasive cervical cancer underwent preoperative evaluation using MR imaging. The results of the MR examinations were correlated with clinical (FIGO) staging under anesthesia (n = 42) and with histopathological findings after operation (n = 26). The staging results of precontrast T1-weighted and T2-weighted turbo spin-echo (TSE) MR images, pre-contrast MR images plus post-contrast enhanced (two-dimensional fast low angle shot (FLASH 2-D) post contrast), pre-contrast MR images plus post-contrast enhanced plus fast dynamic enhanced (single slice turbo fast low angle shot (turbo FLASH)) MR images compared to histopathology (n = 26) were 77%, 81%, and 85%, respectively. The improvement was statistically not significant. The result of MR staging compared to clinical staging (n = 42) with pre-contrast MR images was correct in 79% of the cases. Pre-contrast MR images combined with post-contrast MR images did not significantly improve staging accuracy (83%). Pre-contrast plus post-contrast plus fast dynamic MR imaging improved staging to 91%. However, the improvement was only statistically significant for one reader (p = 0.01), whereas the improvement of the second reader was not significant (p = 0.07). The single slice turbo FLASH images showed enhancement of all squamous cell carcinomas (n = 32) with an average onset of 5 seconds (range 4–8 seconds during the first 45 seconds of bolus injection of gadolinium. The normal cervix showed enhancement with an average of 10 seconds (range 6–14 seconds). FLASH 2-D post-contrast images showed less intense enhancement of the cervical tumors with respect to the parametria and other surrounding structures. Fast dynamic MR imaging and to a lesser degree post-contrast MR imaging showed a higher level of confidence than pre-contrast MR. Fast dynamic MRI compared with clinical staging (n = 42) was correct in 91% (38/42) and to histopathology in 85% (22/26). Comparison of clinical staging with histopathology was 85% (22/26). In conclusion, fast dynamic MR imaging is superior to post-contrast and pre-contrast MR imaging and is at least as good as clinical staging in the evaluation of cervical carcinoma.

Fast dynamic contrast enhanced MR imaging of cervical carcinoma

The first pass phase of contrast material is most important to study vascularization and perfusion of tissue and can be studied using dynamic magnetic resonance (MR) imaging. The purpose of this prospective study was to evaluate the usefulness of pre-contrast vs. post-contrast and fast dynamic MR imaging in the pre-operative staging of cervical carcinomas. To assess the normal onset of enhancement of the uterus and cervix 15 volunteers underwent dynamic MR imaging. Forty-two consecutive patients with invasive cervical cancer underwent pre-operative evaluation using MR imaging. The results of the MR examinations were correlated with clinical (FIGO) staging under anaesthesia (n = 42) and with histopathological findings after operation (n = 26). The staging results of pre-contrast T1-weighted and T2-weighted turbo spin-echo (TSE) MR images, pre-contrast MR images plus post-contrast enhanced (two dimensional fast low angle shot (FLASH 2-D) post contrast), pre-contrast MR images plus post-contrast enhanced plus fast dynamic enhanced (single slice turbo fast low angle shot (turbo FLASH)) MR images compared to histopathology (n = 26) were 77%, 81% and 85% respectively. The improvement was statistically not significant. The result of MR staging compared to clinical staging (n = 42) with pre-contrast MR images was correct in 79% of the cases. Pre-contrast MR images combined with post-contrast MR images did not significantly improve staging accuracy (83%). Pre-contrast plus post-contrast plus fast dynamic MR imaging improved staging to 91%. However, the improvement was only statistically significant for one reader (P = 0.01), whereas the improvement of the second reader was not significant (P = 0.07). The single slice turbo FLASH images showed enhancement of all squamous cell carcinomas (n = 32) with an average onset of 5s (range 4-8s) during the first 45s of bolus injection of gadolinium. The normal cervix showed enhancement with an average of 10s (range 6-14 s). FLASH 2-D post-contrast images showed less intense enhancement of the cervical tumours with respect to the parametria and other surrounding structures. Fast dynamic MR imaging and to a lesser degree post-contrast MR imaging showed a higher level of confidence than pre-contrast MR. Fast dynamic MRI compared with clinical staging (n = 42) was correct in 91% (38/42) and to histopathology in 85% (22/26). Comparison of clinical staging with histopathology was 85% (22/26). In conclusion, fast dynamic MR imaging is superior to post-contrast and pre-contrast MR imaging and is at least as good as clinical staging in the evaluation of cervical carcinoma.

Cervical carcinoma: comparison of standard and pharmacokinetic MR imaging.

To stage advanced cervical carcinoma with conventional or pharmacokinetic magnetic resonance (MR) imaging by correlating imaging findings with whole-mount specimens and histopathologic findings. Twenty-six adult patients with primary cervical cancer (stages IIB-IVA) underwent T2-weighted turbo spin-echo (SE) MR imaging; gadolinium-enhanced, T1-weighted SE MR imaging; and gadolinium-enhanced, saturation-recovery, turbo fast low-angle shot MR imaging. All imaging findings were correlated with the whole-mount specimens and histopathologic findings. Signal intensity changes versus time were analyzed by using a pharmacokinetic model and parameter values displayed as a color-coded overlay. Histopathologic stages were IIB (n = 9), IIIB (n = 1), and IVA (n = 16). The overall accuracy for tumor staging was 73% for T2-weighted, 81% for T1-weighted, and 92% for pharmacokinetic MR imaging. Pharmacokinetic MR imaging was accurate (90%) in the diagnosis of tumor extension into the bladder and/or rectal wall but inaccurate (69%) in that of parametrial invasion. T2-weighted images were most accurate (86%) in the assessment of parametrial tumor extension but less accurate (69%) in that of bladder or rectal invasion. T2-weighted turbo SE images are still superior to contract medium-enhanced T1-weighted SE or pharmacokinetic MR images in the diagnosis of parametrial infiltration by uterine cervical carcinoma. However, pharmacokinetic MR imaging is a promising method for demonstrating and staging IVA disease.