TSE Images Research Articles

Gadolinium containing contrast agents for pulmonary ventilation magnetic resonance imaging: preliminary results.

Five gadolinium containing contrast media (gadopentetate dimeglumine [Magnevist; Berlex Imaging, Montville, NJ, USA], gadobutrol [Gadovist; Schering, Järfälla, Sweden], gadoteridol [ProHance; Bracco-Byk Gulden, Konstanz, Germany], gadobenate dimeglumine [MultiHance; Bracco-Byk Gulden, Konstanz, Germany], and gadopentetate dimeglumine added with mannitol and a surface active detergent) were evaluated for their efficacy in magnetic resonance depiction of lung ventilation. All contrast agent aerosols were generated by a jet nebulizer. Twelve intubated domestic pigs were mechanically ventilated with the respective aerosolized contrast agent and studied on a 1.5 T MR imager. T1-weighted TSE images using respiratory gating were obtained before and after a 10-minute ventilation period. Pulmonary signal intensity (SI) and signal-to-noise (SNR) changes were measured for both lungs. Mean SI increases ranged between 13.5% and 45.8% (right lung) and 14% and 39.8% (left lung). SNR changes ranged from +14.7% to +46.8% and from +13.1% to +40.5% for the right and left lung, respectively. The highest SI and SNR increases were observed in the gadoteridol group. The use of gadolinium for MR ventilation imaging is primarily hindered by its viscosity properties and thus, its capability of aerosolization. Of the five agents tested, the medium with the lowest viscosity at room temperature (gadoteridol) showed the most promising enhancement results. The results reaffirm the potential of gadolinium-based contrast agents as a pulmonary imaging alternative. With a reduction of ventilation duration down to ten minutes, the method appears tolerable in a clinical setting.

MRT der Osteomyelitis: Sensitivität und Spezifität der STIR-Sequenz im Vergleich zur kontrastangehobenen T1-Spinechosequenz

To evaluate the need for additional MR sequences including administration of Gd-DTPA after inconspicuous Short-Tau Inversion-Recovery (STIR) sequence to exclude the diagnosis of osteomyelitis. 112 MR examinations of 79 patients acquired for the detection of possible osteomyelitis were analyzed retrospectively. All examinations were performed at 0.5 T including STIR, T1-weighted spin echo sequences (T1 SE) before and after application of Gd-DTPA. Additionally, 93 T2-weighted spin echo sequences were available. The examinations were analyzed by two experienced radiologists. First, the STIR sequences were studied, followed by the T1 SE images before and after administration of contrast material. Finally, the T2-weighted images were evaluated. Diagnoses were confirmed by operation (22), biopsy (10), and follow-up (80). In 53 cases osteomyelitis was diagnosed, while the remaining 59 cases suffered from another disease. The sensitivity of the STIR sequence was 100% while the specificity for osteomyelitis was 49.2%. The specificity increased to 79.7% by including T1 SE images into the analysis and reached 83.1% after considering the contrast enhanced images. T2-weighted images yielded no additional information. The combination of STIR and T1SE images shows a high sensitivity and specificity for osteomyelitis, thus obviating the need for any additional examinations.

MR features of the denervated tongue in radiation induced neuropathy.

The MR features of the denervated tongue have been described following nerve injury from radical neck dissection and tumour invasion. The purpose of the study was to determine whether similar features are present in the tongue following radiation induced neuropathy (RIN). The clinical records and MR images of 12 patients with RIN of the hypoglossal nerve were reviewed retrospectively. T1 weighted SE images were performed in 12, T2 weighted TSE images in 11, fat suppressed images in 10 and contrast enhanced T1 weighted images in nine patients. The denervated tongue revealed "oedemalike" changes in five, fatty infiltration in six, atrophy in 11 and pseudohypertrophy in one patient. Abnormal enhancement was not identified, and in five patients the signal intensity was normal on all sequences. The oedemalike changes, fatty infiltration and normal signal intensity were seen 2-48, 2-48, and 6-63 months, respectively, after the onset of RIN. In conclusion, there was no discernible relationship between the duration of RIN and the MR appearance of the denervated tongue. Oedemalike changes, previously described in the acute/subacute phase of denervation, were also seen in long-standing disease and there was no associated abnormal enhancement in any case. Furthermore, the signal intensity may be normal, the MR diagnosis relying on asymmetry of the size of the tongue. It is postulated that radiation causes incomplete and ongoing damage of the nerve, the course of which is unpredictable.

MR imaging of cervical spine motion with HASTE

The HASTE (half-Fourier acquisition single-shot turbo spin-echo) technique delivers images with T2-weighting in about half a second and could be ideal for fast dynamic studies when T2-weighting is needed. We evaluated cardiac-triggered HASTE to study cervical spine flexion/extension. The cervical spines of ten asymptomatic volunteers were studied during flexion/extension motion on a 1.5 Tesla imager using a cardiac triggered version of the HASTE technique. Midline sagittal images were acquired every 2 to 3 s during neck flexion and extension. Image quality was compared to traditional T2-weighted Turbo spin-echo. The study duration per flexion/extension was typically less than 20 seconds and well tolerated. The cardiac-gated T2-weighted HASTE images compared favorably to the traditional T2-weighted TSE images in quality and overall anatomic detail. Range of motion averaged: flexion 30° (range 8°–48°) and extension 23° (range 0°–57°). Greatest motion occurred in the lower cervical spine (C4–C7). At the intervertebral discs the canal diameter, anterior and posterior CSF spaces were widest in neutral position and decreased with flexion and extension. Therefore, Cardiac-gated T2 HASTE sequences provide diagnostic and time-efficient dynamic MR images of cervical spine motion.

Discrimination between fluid, synovium, and cartilage in patients with rheumatoid arthritis: Contrast enhanced spin echo versus non-contrast-enhanced fat-suppressed gradient echo MR imaging

PURPOSE: The aim of this study was to compare fat-suppressed T1-weighted 3D-Gradient Echo (GE)-images and conventional T1-weighted contrast-enhanced SE images in the assessment of patients with rheumatoid arthritis in an attempt to improve discrimination of inflamed synovium, joint fluid, and cartilage. PATIENTS AND METHODS: 28 knee joints in 20 patients with rheumatoid arthritis were examined with a 3 D-GE-T1 weighted sequence with frequency-selective fat suppression (Flash 3D fat sat) and T1-weighted SE-sequences after intravenous gadolinium-containing contrast agent administration using a 1.5T system. Differentiation of cartilage, synovium, and joint effusion was assessed on both sequences qualitatively by two observers and quantitatively by signal intensity measurements. RESULTS: Qualititative analysis revealed higher grading rates for cartilage/fluid differentiation with fat-suppressed T1-weighted GE images than contrast enhanced T1-SE images. Quantitative analysis by measurements of contrast-to-noise ratios revealed significantly higher rates for the Flash 3D fat sat with regard to cartilage/fluid discrimination, significantly higher rates for T1-SE post-contrast for cartilage/synovium discrimination, and significantly higher rates for T1-SE post-contrast for synovium/fluid discrimination. CONCLUSION: 3D-GE-imaging with fat-suppressed T1 weighted sequences allows sufficient differentiation of cartilage and joint fluid in patients with rheumatoid arthritis without application of contrast agents and may assist in monitoring disease progression and response to therapy. The higher contrast to noise ratios of cartilage/synovium and synovium/fluid on T1-SE images following administration of gadolinium-containing contrast agents may improve detection of disease activity.

Utility of Dual Echo T2-Weighted Turbo Spin Echo MR Imaging for Differentiation of Solid, Malignant HepaticLesions from Nonsolid, Benign Hepatic Lesions

Purpose : To evaluate the additive value of multiphasic contrast-enhanced dynamic MR imaging as a supple-mentto dual-echo T2-weighted TSE MR imaging for the differentiation of solid, malignant hepatic lesions from nonsolid,benign hepatic lesions. Materials and Methods : Two radiologists retrospectively reviewed dual-echo T2-weightedTSE MR images and gadolinium-enhanced MR images in 51 patients with hepatic lesions (28 malignant, 69 benign). Forthe dif-ferentiation of malignant from benign lesions, as seen on dual-echo T2-weighted TSE MR images, weevaluated sensitivity, specificity, and accuracy, and compared with the results with those for dual echoT2-weighted MR images plus multiphasic contrast-enhanced dynamic MR images. In addition, Az values for dual echoT2-weighted MR images were compared with those for dual echo T2-weighted MR images plus multiphasiccon-trast-enhanced dynamic MR images. Results : For the differentiation of malignant from benign hepatic lesions,as seen on dual-echo T2-weighted TSE images, sensitivity, specificity, and accuracy were 80.0 %, 97.5 %, and 93.9%, respectively, for lesions less than 3 cm in diameter, and 92.3 %, 95.0 %, and 93.5 %, respectively, for thosethat were 3 cm or larger. The results for dual-echo T2-weighted MR imaging plus multiphasic contrast-enhanceddynamic MR imaging were 86.7%, 100.0%, and 97.3%, respectively, for lesions less than 3 cm, and 92.3%, 100.0 %,and 95.7 %, re-spectively for those that were 3 cm or larger. There were no significant differences insensitivity, specificity, or accuracy between the results obtained using dual-echo T2-weighted MR imaging andthose obtained with d-ual- echo T2-weighted MR imaging plus multiphasic contrast-enhanced dynamic MR imaging. Norwere there statistically significant differences in Az values between the two groups. Conclusions : For thedifferentiation of solid, malignant hepatic lesions from nonsolid, benign hepatic lesions, there is no differencein accuracy between dual-echo T2-weighted TSE MR imaging and the additional use of multiphasic contrast-enhancedMR imaging. Dual-echo T2-weighted TSE MR imaging may, therefore, be use-ful for the differentiation of solid,malignant hepatic lesions from nonsolid, benign hepatic lesions without the use of multiphasic contrast-enhancedMR imaging.

MRT des weiblichen Beckens:Turbo-Spin-Echo-(TSE)-Sequenzen im Vergleich mit konventionellen Spin-Echo-Sequenzen bei 0,5 Tesla

Markedly T2-weighted MR images of the pelvis can be obtained with TSE sequences using short acquisition times. In order to determine whether TSE sequences at 0.5 Tesla produce diagnostically valuable images, 9 normals and 53 patients with suspected gynaecological tumours were examined with TSE and SE sequences. Visual comparison showed a considerable superiority of the TSE sequences in most respects. The quality of the TSE images was regarded as very good in 82% and good in 18% (SE sequences: 27% very good, 55% good, 18% moderate), delineation of anatomical structures 81% very good and 19% good (SE sequence: 31% very good, 53% good, 16% moderate). TSE sequences were also superior in the detection of pathological changes (87% very good, 13% good) compared with SE sequences (56% very good, 37% good, 7% moderate). Venous plexuses in the parametrium were better demonstrated by SE sequences. There were significantly higher signal to noise ratios (SNR) with TSE sequences for fat, bone marrow (each p < 0.001), and urine (p < 0.05). Using muscle as reference tissue, there were significantly higher signal-difference to noise ratios (SDR) for fat (p < 0.001), and bone marrow (p < 0.0001), the other pelvic organs and tumours showed no significant differences between the SNR and SDR. TSE sequences are well suited to replace SE sequences in the MR diagnosis of gynaecological tumours.