Gadoteridol in multiple sclerosis patients: A comparison of single and triple dose with immediate vs. delayed imaging

Enhancement of lesions in multiple sclerosis (MS) has been investigated using standard and high doses of gadolinium. The purposes of this study are to compare the relative merits of single and triple dose as well as examine the merits of delayed triple-dose images in a large group of patients. Thirty-seven patients with multiple sclerosis underwent contrast enhanced brain magnetic resonance imaging (MRI). After noncontrast images, a single dose (0.1 mmol/kg) of gadoteridol was administered. Subsequently, axial T1-weighted images were obtained immediately after administration, and again after a delay of approximately 20 minutes. After an additional 0.2-mmol/kg dose was administered, to provide a total cumulative dose of 0.3 mmol/kg of gadoteridol, immediate and delayed axial T1-weighted image sequences were repeated. The contrast-noise ratio (C/N) was calculated for each identified, enhancing lesion in each series. Furthermore, blinded readings were performed to determine the lesion detection rate. Of the forty definite lesions that underwent all four sequences, triple-dose delayed images exhibited the highest contrast-noise ratio in a significantly larger number of lesions (p < 0.0001). Triple-dose immediate and delayed scans resulted in significantly higher contrast-noise ratios (6.47 and 9.99, respectively) when compared with those of the single dose scans (3.4 for immediate scans and 5.24 for delayed) (p < 0.01). The lesion detection rate was highest for triple dose delayed (95%), followed by triple-dose immediate (83%), single-dose delayed (68%) and finally, single-dose immediate scans (43%). Triple-dose immediate was noted to have a significantly increased (p < 0.0002) lesion detection rate with respect to the standard-dose immediate scans and standard-dose delayed scans (p < 0.02). In four lesions (10% of the total number of lesions), detection occurred only with the triple-dose delayed image sequence. Triple-dose 0.3 mmol/kg gadolinium with delayed imaging resulted in the highest lesion conspicuity and the highest lesion identification rate. There was a trend of progressively increasing detection rates from single-dose immediate scans to triple-dose delayed scans. Triple-dose delayed scans resulted in significantly higher (p < 2 × 10⁻⁸) contrast noise ratios than all other sequences of this study.     

Three subsequent single doses of gadolinium chelate for brain MR imaging in multiple sclerosis

BACKGROUND AND PURPOSE: A triple-dose (TD) of gadolinium chelate is highly sensitive approach for detecting lesion activity in multiple sclerosis (MS). However, individual TD injections do not provide data on the severity of the pathologic process in a population of lesions, and its clinical use is limited by the cost-benefit considerations. Our aim was to determine whether the use of three subsequent single doses (SD) of a gadolinium chelate in brain MR imaging is useful in detecting MS lesions with different patterns of enhancement. METHODS: In 10 patients, T1-weighted spin-echo images were acquired before and after three intravenous administrations of 0.1 mmol/kg of gadodiamide. RESULTS: In all patients, SD images showed six enhancing lesions; double-dose (DD) images, 13; and TD images, 22. Differences between SD and TD and between DD and TD were significant (P <.018). Six lesions (27%) enhanced with all the three doses; seven (32%), with both DD and TD; and nine (41%), with only TD. Proportions of patients with at least one enhancing lesion were, for SD, four of 10; DD, seven of 10; and TD, nine of 10. In defining active disease in these nine patients, we needed only 19 SDs versus the 30 SDs that would have been needed if individual TD injections were used. CONCLUSION: With three subsequent SD injections, the number of enhancing lesions progressively increases. This approach allows the distinction of three levels of enhancement, and it reduces the amount of contrast agent needed to distinguish patients with active MS from those with nonactive MS.     

Liver lesion conspicuity: T2-weighted breath-hold fast spin-echo MR imaging before and after gadolinium enhancement--initial experience

PURPOSE: To evaluate the effect of a gadolinium chelate on T2-weighted breath-hold fast spin-echo magnetic resonance images of focal hepatic lesions. MATERIALS AND METHODS: In 21 patients with focal hepatic lesions, identical T2-weighted breath-hold fast spin-echo images were obtained before and after gadolinium enhancement and were compared regarding lesion-to-liver contrast-to-noise ratio, signal-to-noise ratio, lesion conspicuity, and vascular pulsation artifact. Image review was performed independently, in random order, by two experienced radiologists. RESULTS: For solid lesions, the lesion-to-liver contrast-to-noise ratio on enhanced images was significantly higher (P <.05) than that on nonenhanced images. For nonsolid lesions, however, there was no significant difference (P =.07). For both readers, lesion conspicuity for solid lesions on enhanced images was significantly higher than on nonenhanced images (P <.05). Severity of vascular pulsation artifact was not significantly different. CONCLUSION: Solid-lesion contrast on T2-weighted breath-hold fast spin-echo images improves after administration of a gadolinium chelate. These images should be obtained after, rather than before, gadolinium enhancement.     

Comparison of two MR sequences for the detection of multiple sclerosis lesions in the spinal cord.

PURPOSETo compare cardiac-triggered dual-echo spin-echo and magnetization transfer-prepared gradient-echo (MT-GE) MR imaging in the detection of multiple sclerosis (MS) lesions in the spinal cord.METHODSThe cervical spinal cord in 20 patients with MS and in nine healthy volunteers was examined with spin-echo and MT-GE MR imaging. Sagittal images were scored for number of lesions, certainty about lesions, image quality, and visual hindrance by artifacts in random order by two radiologists separately and in a blinded manner.RESULTSIn one healthy volunteer, a lesion was seen on images obtained with both images. Lesion/cord contrast-to-noise ratio was equal on both the MT-GE and T2-weighted spin-echo images. MT-GE images showed better image quality and fewer artifacts than the spin-echo images did. The readers found approximately the same number of lesions. However, the number of definite lesions was higher for the spin-echo sequence than for the MT-GE sequence. One reader found 45 definite lesions with spin-echo and 34 definite lesions with MT-GE. For the other reader, these numbers were 37 (spin-echo) and 31 (MT-GE). On the spin-echo images, 90% of the patients were considered to have definite lesions; on the MT-GE images, the readers found definite lesions in 65% (reader 1) and in 70% (reader 2) of the patients.CONCLUSIONImage quality was better with the MT-GE technique than with the spin-echo technique, and lesion/cord contrast-to-noise ratio on the MT-GE images was equal to that of T2-weighted spin-echo images. However, for detecting spinal cord MS lesions in the sagittal plane, the spin-echo images were preferred to the MT-GE images.     

Serial isotropic three-dimensional fast FLAIR imaging: using image registration and subtraction to reveal active multiple sclerosis lesions

OBJECTIVE: Image registration and subtraction to detect the change of disease burden in multiple sclerosis on serial MR images should benefit from the use of high-resolution isotropic voxels. We compared 1.2-mm isotropic three-dimensional (3D) fast fluid-attenuated inversion recovery (FLAIR) images with standard 3-mm two-dimensional spin-echo images for the detection of new or enlarging lesions in longitudinal studies. SUBJECTS AND METHODS: Serial MR images were obtained at baseline, month 6 (n = 20), and month 7 (n = 16). For the half-yearly intervals, subtracted 3D FLAIR images and T2-weighted spin-echo images were compared. For the monthly intervals, subtracted 3D FLAIR images were compared with triple-dose contrast-enhanced T1-weighted spin-echo images. New, enlarging, and enhancing lesions were marked in consensus by two radiologists. RESULTS: At the half-yearly intervals, 3D FLAIR imaging detected more new or enlarging lesions than T2-weighted spin-echo imaging, both at the initial interpretation (80 vs 52; p < 0.001) and after a side-by-side comparison of the lesions (88 vs 65; p < 0.001). Post hoc analyses showed the largest benefit for new (rather than enlarging), for small, and for temporal lesions. At the monthly intervals, 32 enhancing lesions were detected on contrast-enhanced T1-weighted spin-echo images versus 20 new or enlarging lesions detected on 3D FLAIR images (p < 0.05). After a side-by-side comparison of the lesions, seven additional lesions were identified on 3D FLAIR images, making the difference with contrast-enhanced T1-weighted spin-echo images insignificant (27 vs 32; p > 0.05). CONCLUSION: Isotropic 3D FLAIR imaging holds great promise for the detection of new or enlarging lesions in multiple sclerosis using registration and subtraction techniques certainly at longer intervals.     

T1-weighted three-dimensional magnetization transfer MR of the brain: improved lesion contrast enhancement.

PURPOSEWe developed and evaluated clinically T1-weighted three-dimensional gradient-echo magnetization transfer (MT) sequences for contrast-enhanced MR imaging of the brain.METHODSA short-repetition-time, radio frequency-spoiled, 3-D sequence was developed with a 10-millisecond MT pulse at high MT power and narrow MT pulse-frequency offset, and the enhancing lesion-to-normal white matter background (L/B) and the contrast-to-noise (C/N) ratios on these images were compared with those on T1-weighted spin-echo images and on non-MT 3-D gradient-echo images in a prospective study of 45 patients with 62 enhancing lesions. In the 24 patients who had intracranial metastatic disease, the number of lesions was counted and compared on the three types of images.RESULTSThe MT ratio of normal callosal white matter was 55% on the MT 3-D gradient-echo sequences. The L/B and C/N on the MT 3-D gradient-echo images were more than double those on the 3-D gradient-echo images, and were significantly greater than those on the T1-weighted spin-echo images. In patients with metastatic disease, the MT 3-D gradient-echo images showed significantly more lesions than did the T1-weighted spin-echo or 3-D gradient-echo images.CONCLUSIONMT 3-D gradient-echo MR imaging improves the contrast between enhancing lesion and background white matter over that obtained with conventional T1-weighted 3-D gradient-echo and spin-echo imaging. MT 3-D gradient-echo imaging provides practical sampling, image coverage, and spatial resolution, attributes that may be advantageous over MT T1-weighted spin-echo techniques.     

The value of chemical fat-saturation pulse added to T1-weighted spin-echo sequence in evaluating gadolinium-enhancing brain lesions in multiple sclerosis

PURPOSE: This study was undertaken to assess the value of a chemical (spectral) fat-saturation (fat-sat) pulse added to a T1-weighted spin-echo sequence after intravenous administration of paramagnetic contrast agent in detecting enhancing lesions in multiple sclerosis. MATERIALS AND METHODS: Twenty patients with relapsing-remitting multiple sclerosis underwent a brain 1.0-Tesla magnetic resonance (MR) scan with T1-weighted spin-echo sequences (24 contiguous para-axial slices with a thickness of 5 mm, pixel size 0.96 mm(2), number of excitations 2, flip angle 90 degrees ) 5 min after intravenous injection of 0.1 mmol/kg of gadodiamide with and without fat-sat, acquired with randomised order of priority. Two readers counted by consensus the number of enhancing lesions and assigned a conspicuity score (low conspicuity=1; high conspicuity=2) to each enhancing lesion during a randomised reading without any visual comparison between the two corresponding images (with and without fat-sat) of the same patient. McNemar and Wilcoxon matched-pair signed-rank tests were used. RESULTS: Seventy-two enhancing lesions without fat-sat and 94 with fat-sat were detected; 22 lesions were visible only with fat-sat, whereas no lesion was detected only without fat-sat (p<0.0001). The conspicuity score was 1.17+/-0.38 (mean+/-standard deviation) and 1.57+/-0.44, respectively (p<0.0001). CONCLUSIONS: A fat-sat pulse added to a T1-weighted spin-echo sequence increases significantly the number and conspicuity of contrast-enhancing lesions in patients with relapsing-remitting multiple sclerosis.     

The effect of gadolinium on the sensitivity and specificity of MR in the initial diagnosis of multiple sclerosis.

PURPOSETo determine whether gadolinium can improve the sensitivity and specificity of MR imaging for the initial diagnosis of multiple sclerosis.METHODSPatients (n = 57) with neurologic symptoms suggesting multiple sclerosis were studied prospectively. MR imaging consisted of T2-weighted and gadolinium-enhanced T1-weighted spin-echo images. Lumbar puncture was performed for cerebrospinal fluid analysis in 34 patients.RESULTSAfter imaging, 17 patients (35%) had clinically definite multiple sclerosis. Cerebrospinal fluid examination had a sensitivity of 69% and specificity of 38%. Using liberal criteria, the sensitivity of T2-weighted MR imaging was 94% and the specificity 55%; using more strict criteria, the specificity increased to 65% with a sensitivity of 88%. Gadopentetate dimeglumine enhancement increased the specificity further to 80% with a loss of sensitivity (59%).CONCLUSIONGadolinium enhancement increases the specificity of MR imaging in the early diagnosis of multiple sclerosis.     

Enhancement of cerebral diseases: how much contrast agent is enough? Comparison of 0.1, 0.2, and 0.3 mmol/kg gadoteridol at 0.2 T with 0.1 mmol/kg gadoteridol at 1.5 T

RATIONALE AND OBJECTIVES: To determine the clinical dose of gadoteridol (ProHance, Bracco-Byk Gulden) to use for the assessment of blood-brain barrier breakdown on low-field magnetic resonance (MR) scanners that corresponds to a standard dose of gadoteridol on high-field MR scanners. METHODS: This prospective study was carried out at four centers. A total of 138 patients with suspected or known brain diseases underwent a routine head scan comprising precontrast T2-weighted turbo spin-echo and T1-weighted spin-echo sequences on a 1.5-T MR scanner. After administration of a standard dose of 0.1 mmol/kg gadoteridol, the T1-weighted scan was repeated after a delay of 15 to 20 minutes. For continuing the examination on a 0.2-T MR scanner (Magnetom OPEN, Siemens), a standard-dose T1 spin-echo sequence was started within 30 to 50 minutes of the first injection. Then two additional T1-weighted low-field sequences were each started 5 minutes after two additional doses of 0.1 mmol/kg gadoteridol. Eighty patients with enhancing lesions underwent an intraindividual comparison. Evaluation of the overall numbers of lesions detected and of lesion size and character was performed on-site as well as off-site by two independent readers. RESULTS: The single-dose, low-field sequence detected significantly fewer enhancing lesions (80/95 lesions; P < 0.05), particularly metastases and infarctions, than did the standard-dose, high-field sequence. No statistically relevant differences (reader 1: P = 1; reader 2: P = 0.8) were found between the double- and triple-dose, low-field sequences and the standard-dose, high-field sequence. Primary brain tumors were detected by all postcontrast sequences irrespective of the dose. CONCLUSIONS: At low field, the clinically equivalent dose to 0.1 mmol/kg gadoteridol at high field is 0.2 mmol/kg. A dose of 0.1 mmol/kg gadoteridol is less effective and cannot be recommended for use on extremely low-field scanners.     

Patterns of lesion development in multiple sclerosis: longitudinal observations with T1-weighted spin-echo and magnetization transfer MR.

PURPOSEWe evaluated the appearance of enhancing multiple sclerosis (MS) lesions on unenhanced T1-weighted MR images and the natural course of enhancing MS lesions on serial unenhanced T1-weighted and magnetization transfer (MT) MR images.METHODSOne hundred twenty-six enhancing lesions were followed up monthly for 6 to 12 months to determine their signal intensity on unenhanced T1-weighted and MT MR images. At the time of initial enhancement, the size of the lesion and the contrast ratio of enhancement were calculated for each enhancing lesion. During follow-up, the contrast ratio on the corresponding unenhanced T1-weighted image was measured, and an MT ratio (MTR) was calculated.RESULTSTwenty-five enhancing lesions (20%) appeared isointense and 101 lesions (80%) appeared hypointense relative to normal-appearing white matter on unenhanced T1-weighted images. During 6 months of follow-up, four MR patterns of active lesions were detected: initially isointense lesions remained isointense (15%); initially isointense lesions became hypointense (5%, most of which reenhanced); initially hypointense lesions became isointense (44%); and initially hypointense lesions remained hypointense (36%). MTR was significantly lower for hypointense lesions as compared with isointense lesions at the time of initial enhancement. For lesions that changed from hypointense to isointense, MTR increased significantly during 6 months of follow-up. Multiple regression analysis showed that strongly decreased MTR at the time of initial enhancement and enhancement duration of more than one scan were predictive of a hypointense appearance on unenhanced T1-weighted images at 6 months'' follow-up. Ring enhancement was found to be the only (weak) predictor of persistently hypointense signal intensity.CONCLUSIONMost enhancing lesions appear slightly to significantly hypointense on unenhanced T1-weighted images. Although most hypointensities are reversible, only those lesions that fail to recover on unenhanced T1-weighted and MT images may have considerable irreversible structural changes.     

MR of intracranial tumors: combined use of gadolinium and magnetization transfer.

PURPOSETo study the potential combined application of gadolinium and magnetization transfer in the MR imaging of intracranial tumors.METHODSTwenty-two patients were imaged at low field strength (0.1 T). Corresponding gradient-echo partial saturation images without and with magnetization transfer pulse were produced. Images with intermediate repetition times were obtained in 18 cases; five different sequences were produced in 4 cases. Gadopentetate dimeglumine was used at a dose of 0.1 mmol/kg.RESULTSMagnetization transfer effect increased the contrast between enhancing lesion and normal brain and the contrast between edema and normal brain; the contrast between enhancing lesion and edema was not significantly changed. On intermediate-repetition-time magnetization transfer images the contrast between enhancing tumor and normal brain and the contrast between edema and normal brain were superior to short-repetition-time magnetization transfer images, but the differentiation between enhancing tumor and edema was poorer.CONCLUSIONMagnetization transfer can be used to improve contrast in Gd-enhanced MR imaging. Combining magnetization transfer with an intermediate-repetition-time image provides the possibility for displaying both enhancing and nonenhancing lesions on a single MR image.     

Inversion-recovery echo-planar MR in adult brain neoplasia.

PURPOSEA T1-weighted multishot inversion-recovery (IR) echo-planar MR imaging (EPI) sequence was developed to improve intracranial tissue differentiation; its diagnostic utility was compared with that of conventional axial T1-weighted spin-echo and axial T2-weighted turbo spin-echo sequences.METHODSEighteen patients with known or suspected primary or metastatic brain neoplasia were imaged in a 1.5-T unit with IR-EPI sequences. Three observers measured gray/white matter contrast-to-noise ratios and subjectively compared IR-EPI sequences with T1-weighted spin-echo and T2-weighted turbo spin-echo sequences for gray/white matter discrimination, visibility of intracranial and vascular structures, overall lesion conspicuity, size of lesion(s), and presence and severity of artifacts.RESULTSTwenty-four lesions (including neoplasia, infarction, treatment-associated encephalomalacia, nonneoplastic white matter signal abnormalities, and basilar artery dolichoectasia) were detected in 12 patients. Basilar artery dolichoectasia was not included in subsequent statistical analysis. Pulsatile flow artifacts were markedly reduced on IR-EPI sequences relative to those on T1-weighted spin-echo sequences. Gray/white matter contrast was greater on IR-EPI images than on T1-weighted spin-echo images. Periaqueductal gray matter, basal ganglia, optic tracts, cranial nerve V, and claustrum were seen better or as well on IR-EPI images as compared with T1-weighted spin-echo images. IR-EPI was more sensitive to magnetic sensitivity effects, with resultant decreased visibility of cranial nerves VII and VIII and the orbital portion of the optic nerves. For noncontrast sequences, lesion conspicuity was better on IR-EPI images than on T1-weighted spin-echo images in 16 (70%) of 23 lesions and was equal on the two sequences in seven (30%) of 23 lesions. Lesion size, including surrounding edema, was greater on IR-EPI images than on T2-weighted turbo spin-echo images in two (9%) of 23 cases and equal in 21 (91%) of 23 cases. Hyperintense foci of methemoglobin were more conspicuous on T1-weighted spin-echo images.CONCLUSIONMultishot IR-EPI is superior to conventional T1-weighted spin-echo imaging for parenchymal tissue contrast and lesion conspicuity, and is equal to T2-weighted turbo spin-echo imaging in sensitivity to pathologic entities.     

Superparamagnetic Iron Oxide Hepatic MR Imaging: Efficacy and Safety Using Conventional and Fast Spin-Echo Pulse Sequences

The purpose of this study was to evaluate the technical efficacy and safety of iv ferumozldes (Feridex^a), a superparamagnetic iron oxide contrast agent for detection of hepatic lesions using conventional spin-echo and fast spin-echo MR images. Precontract and postcontrast MR studies were performed on 25 patients with suspected focal hepatic lesions. Conventional Tl-and T2-weighted MR images, as well as fast spin-echo and fat suppressed fast spin-echo MR images, were evaluated. Quantitative assessment of the contrast agent was performed obtaining region of interest measurements of the liver, spleen, and selected hepatic lesions. The pulse sequences were also evaluated subjectively for overall image quality and a subjective assessment of lesion detection. The use of a superparamagnetic iron oxide contrast agent led to a decrease in hepatic signal intensity on all pulse sequences. Lesion-to-liver contrast increased 41.1%, 36.5%, and 32.0% on the conventional T2, fast spin-echo, and fat suppressed fast spin echo pulse sequences, respectively. Lesion-to-liver contrast decreased on the T1-weighted postcontrast pulse sequence by 23.8%. Despite Improvement in lesion-to-liver contrast, radiologists subjectively preferred the precontract sequences because of overall better image quality. At a dose of 10 μmol/kg, fenunoxides favorably impacts lesion-to-liver contrast, and may be useful in hepatic imaging, more with conventional T2-weighted spin-echo pulse sequences than with T2-weighted fast spin-echo pulse sequences.     

Magnetization transfer effects in MR-detected multiple sclerosis lesions: comparison with gadolinium-enhanced spin-echo images and nonenhanced T1-weighted images.

PURPOSETo define the relationship between magnetization transfer and blood-brain-barrier breakdown in multiple sclerosis lesions using gadolinium enhancement as an index of the latter.METHODSTwo hundred twenty lesions (high-signal abnormalities on T2-weighted images) in 35 multiple sclerosis patients were studied with gadolinium-enhanced spin-echo imaging and magnetization transfer. Lesions were divided into groups having nodular or uniform enhancement, ring enhancement, or no enhancement after gadolinium administration. For 133 lesions, T1-weighted images without contrast enhancement were also analyzed. These lesions were categorized as isointense or hypointense based on their appearance on the unenhanced T1-weighted images.RESULTSThere was no difference between the magnetization transfer ratio (MTR) of lesions as a function of enhancement. MTR of hypointense lesions on unenhanced T1-weighted images was, however, lower than the MTR of isointense lesions.CONCLUSIONWe speculate that diminished MTR may reflect diminished myelin content and that hypointensity on T1-weighted images corresponds to demyelination. Central regions of ring-enhancing lesions had a lower MTR than the periphery, suggesting that demyelination in multiple sclerosis lesions occurs centrifugally. In addition, the short-repetition-time pulse sequence seems useful in the evaluation of myelin loss in patients with multiple sclerosis.     

Comparison of single- and triple-dose contrast material in the MR screening of brain metastases.

PURPOSEAlthough studies obtained with triple-dose contrast administration can show more brain metastases than those obtained with single-dose contrast material in patients with multiple metastases, such studies are costly and of limited clinical benefit. Since most patients who undergo screening have negative findings or a single metastasis, this study was performed to compare the clinical utility of single-dose versus triple-dose contrast administration in this large group of patients who could benefit from the possible increased sensitivity in lesion detection.METHODSNinety-two consecutive patients with negative or equivocal findings or a solitary metastasis on single-dose contrast-enhanced MR images underwent triple-dose studies. Findings were compared with a standard of reference composed of panel review and long-term follow-up. Further analysis was performed by comparing results with those obtained by two blinded readers.RESULTSIn all 70 negative single-dose studies, the triple-dose studies depicted no additional metastases in terms of the standard of reference. No statistically significant difference was seen between the results of the single- and triple-dose studies. For 10 equivocal single-dose studies, the triple-dose study helped clarify the presence or absence of metastases in 50% of the cases. In 12 patients with a solitary metastasis seen on the single-dose study, the triple-dose study depicted additional metastases in 25% of the cases. In the results of one of the two blinded readers, use of triple-dose contrast led to a statistical difference by decreasing the number of equivocal readings but at the expense of increasing the number of false-positive readings.CONCLUSIONRoutine triple-dose contrast administration in all cases of suspected brain metastasis is not helpful. On the basis of our investigation, we conclude that the use of triple-dose contrast material is beneficial in selected cases with equivocal findings or solitary metastasis, although with the disadvantage of increasing the number of false-positive results.     

Spinal cord lesions in patients with multiple sclerosis: comparison of MR pulse sequences.

PURPOSETo compare T2-weighted conventional spin-echo (CSE), fast spin-echo (FSE), shorttau inversion recovery (STIR) FSE, and fluid-attenuated inversion recovery (FLAIR) FSE sequences in the assessment of cervical multiple sclerosis plaques.METHODSTwenty patients with clinically confirmed multiple sclerosis and signs of cervical cord involvement were examined on a 1.5-T MR system. Sagittal images of T2-weighted and proton density-weighted CSE sequences, T2-weighted FSE sequences with two different sets of sequence parameters, STIR-FSE sequences, and FLAIR-FSE sequences were compared by two independent observers. In addition, contrast-to-noise measurements were obtained.RESULTSSpinal multiple sclerosis plaques were seen best on STIR-FSE images, which yielded the highest lesion contrast. Among the T2-weighted sequences, the FSE technique provided better image quality than did the CSE technique, but lesion visibility was improved only with a repetition time/echo time of 2500/90; parameters of 3000/150 provided poor lesion contrast but the best myelographic effect and overall image quality. CSE images were degraded by prominent image noise; FLAIR-FSE images showed poor lesion contrast and strong cerebrospinal fluid pulsation artifacts.CONCLUSIONSThe STIR-FSE sequence is the best choice for assessment of spinal multiple sclerosis plaques. For T2-weighted FSE sequences, shorter echo times are advantageous for spinal cord imaging, long echo times are superior for extramedullary and extradural disease. FLAIR-FSE sequences do not contribute much to spinal imaging for multiple sclerosis detection.     

Preliminary clinical trial of gadodiamide injection: a new nonionic gadolinium contrast agent for MR imaging.

The safety and efficacy of a newly developed intravenous formulation of the nonionic contrast agent gadolinium diethylenetriaminepentaacetic acid-bis(methylamide), formulated as gadodiamide injection, was investigated. In 30 patients who underwent spin-echo magnetic resonance (MR) imaging before and after contrast agent enhancement, the enhanced images had characteristics judged similar to those of images enhanced by means of available gadolinium compounds. In 15 patients, contrast agent administration was of major diagnostic help, either revealing lesions not apparent without enhancement or providing important lesion characterization. In 12 patients, the lack of abnormal enhancement patterns was important in excluding the presence of disease. In three patients, the contrast agent did not provide information additional to that obtained with the unenhanced T1- and T2-weighted images. No clinically significant changes were observed in vital signs, neurologic status, or laboratory results. The authors conclude that, in this limited series, gadodiamide injection proved to be a safe and useful MR imaging contrast agent for evaluation of the central nervous system and surrounding structures.     

Magnetization transfer contrast of hepatic lesions in breath-hold gradient-echo images of different T1 weighting

Seventeen patients with hepatic lesions [six metastases from colon, breast, and gallbladder carcinoma; one gallbladder carcinoma; five hepatocellular carcinoma; three focal nodular hyperplasia (FNH); one adenoma; and one cyst] were examined by MR breath-hold two-dimensional gradient-echo imaging to assess the potential of magnetization transfer contrast (MTC) for improved conspicuity and classification. Imaging sequences were applied with and without irradiation of off-resonant radiofrequency (RF) prepulses, but other parameters were unchanged. Therefore, quantitative assessment of MTC could be performed. In contrast to former examinations of other researchers, no significant difference of MTC was found between malignant liver lesions and benign lesions as FNH or adenoma. MTC might provide differentiation between hemangioma and cysts versus solid tumors, but MTC is not capable of distinguishing benign and malignant types of solid liver tumors. Effects of unchanged MTC prepulses on signal intensity of normal liver tissue and most lesions were more pronounced for nearly proton density-weighted fast low-angle shot (FLASH) images than for T1-weighted FLASH images, obtained by using higher excitation flip angles. Liver-to-lesion contrast could not be improved clearly by MTC prepulses. The contrast between liver and lesions in the gradient-echo breath-hold images was compared with standard T1- and T2-weighted spin-echo images. Liver-to-lesion contrast in the breath-hold images was found to be inferior to T2-weighted spin-echo images in 14 of 17 cases. Lesion conspicuity in regions near the diaphragm was better in breath-hold images, because problems with marked breathing motion (as in standard imaging) could be avoided.     

Verbesserter Tumorkontrast und -abgrenzung in der stereotaktischen Strahlentherapieplanung zerebraler Gliome und Metastasen mit kontrastmittelunterstützter FLAIR-Bildgebung

BACKGROUND: FLAIR MR imaging has shown to be a valuable imaging modality in pathologic lesions of the brain including intra-axial brain tumors. The aim of the study was to assess the value of a FLAIR technique in the planning process of stereotactic radiotherapy in patients with cerebral gliomas and metastases. PATIENTS AND METHODS: Thirty-five patients with cerebral gliomas and 12 patients with a total of 39 cerebral metastases were examined by T2/PD-weighted fast spin-echo, fast FLAIR prior and after contrast and contrast enhanced T1-weighted spin-echo using identical slice parameters. The images were evaluated by using quantitative and qualitative criteria. Quantitative criteria were tumor-to-background and tumor-to-cerebrospinal fluid contrast and contrast-to-noise. The qualitative evaluation was performed as a multireader analysis concerning lesion detection, lesion delineation and image artifacts. RESULTS: In the qualitative evaluation (Table 3 and 6), all readers found the fast FLAIR images to be superior to fast spin-echo in the exact delineation of cerebral tumors (p < 0.001) and the delineation of enhancing and non enhancing tumor parts. Fast FLAIR was superior in the delineation of cortically located and small lesions but was limited in lesions adjacent to the ventricles. Fast FLAIR provided a significantly better tumor-to-CSF contrast and tumor-to-CSF contrast-to-noise (p < 0.001) (Tables 1, 2a, 2b, 4, 5). The tumor-to-background contrast and tumor-to-background contrast-to-noise of the fast FLAIR images were lower than that of T2-weighted spin-echo images but were significantly increased after the application of contrast media. FLAIR images had more image artifacts, but the image interpretation was not influenced. CONCLUSIONS: FLAIR MR imaging was found to be a valuable sequence in the planning protocol of stereotactic radiotherapy. The concurrent presentation of enhancing and non enhancing tumor tissue on contrast enhanced fast FLAIR imaging enables to use a single imaging sequence in the treatment protocol. This enables to load a reduced image amount into the radiotherapy planning software, is therefore time saving and reduces potential errors.     

Hepatic and hepatocarcinoma magnetic resonance: comparison of the results obtained with paramagnetic (gadolinium) and superparamagnetic (iron oxide particles) contrast media

PURPOSE: To compare prospectively dynamic gadolinium (Gd)-enhanced with superparamagnetic iron oxide (SPIO)-enhanced MRI for the detection of hepatocellular carcinoma (HCC). MATERIAL AND METHODS: Twenty-five patients with histologically proven HCC and liver cirrhosis (28% of them in B or C Child class) underwent dynamic Gd-enhanced MRI and, a few days later, (mean interval: three days) SPIO-enhanced MRI. Only patients with availability of clinical and imaging follow-up for at least seven months were enrolled in this prospective study. Axial dynamic Gd-enhanced imaging was performed with T1 gradient-recalled echo (GRE) sequences. Both axial and sagittal SPIO-enhanced imaging were performed with respiratory triggered T2-weighted turbo spin-echo (TSE) and T1-T2*-weighted GRE sequences. MR images were reviewed by two independent radiologists. The readers scored each lesion for the presence of HCC and assigned confidence levels based on a five-grade scale: 1, definitely or almost definitely absent; 2, possibly present; 3, probably present; 4, definitely present; 5, definitely present with optimal liver/lesion contrast or good liver/lesion contrast and morphological signs (intact capsule, intranodular septa, extra-capsular infiltration), useful for locoregional treatment planning. A positive diagnostic value was assessed for scores of 3 or higher. RESULTS: Gd-enhanced and SPIO-enhanced MRI found 44 lesions. The combined use of TSE and GRE SPIO-enhanced sequences detected 11 more lesions (25% improvement in sensitivity) than Gd-enhanced MRI. One lesion (2.27%) was detected only with Gd-enhanced MRI. Eight of twelve lesions visible with a single contrast agent measured less than 1 cm in diameter. HCC detectability was 75% with Gd-enhanced MRI and 97.7% with SPIO-enhanced MRI. SPIO-enhanced T2-weighted TSE images showed significantly higher diagnostic value than SPIO-enhanced T1-T2*GRE images only in three cases, while nodule morphological characteristics (capsule, septa, different cell differentiation components) were better depicted by TSE images. DISCUSSION AND CONCLUSIONS: In our study the combined use of SPIO-enhanced T2-weighted TSE and T1-T2*-weighted GRE sequences showed higher sensitivity than gadolinium-enhanced GRE dynamic imaging (97.7% versus 75%). These results are at least partly related to our study conditions, that is: 1) MRI was performed with a 1T system, 2) both axial and sagittal SPIO-enhanced imaging were performed with respiratory triggered T2-weighted TSE and T1-T2*-weighted GRE, 3) there was a low freaquency of severe cirrhosis.