T2-weighted Signal Intensity Ratio Research Articles

Myocardial Tissue Characterization in Patients with Hypertensive Crisis, Positive Troponin, and Unobstructed Coronary Arteries: A Cardiovascular Magnetic Resonance-Based Study.

Hypertensive crisis can present with cardiac troponin elevation and unobstructed coronary arteries. We used cardiac magnetic resonance (CMR) imaging to characterize the myocardial tissue in patients with hypertensive crisis, elevated cardiac troponin, and unobstructed coronary arteries. Patients with hypertensive crisis and elevated cardiac troponin with coronary artery stenosis <50% were enrolled. Patients with troponin-negative hypertensive crisis served as controls. All participants underwent CMR imaging at 1.5 Tesla. Imaging biomarkers and tissue characteristics were compared between the groups. There were 19 patients (63% male) with elevated troponin and 24 (33% male) troponin-negative controls. The troponin-positive group was older (57 ± 11 years vs. 47 ± 14 years, p = 0.015). The groups had similar T2-weighted signal intensity ratios and native T1 times. T2 relaxation times were longer in the troponin-positive group, and the difference remained significant after excluding infarct-pattern late gadolinium enhancement (LGE) from the analysis. Extracellular volume (ECV) was higher in the troponin-positive group (25 ± 4 ms vs. 22 ± 3 ms, p = 0.008) and correlated strongly with T2 relaxation time (rs = 0.701, p = 0.022). Late gadolinium enhancement was 32% more prevalent in the troponin-positive group (82% vs. 50%, p = 0.050), with 29% having infarct-pattern LGE. T2 relaxation time was independently associated with troponin positivity (OR 2.1, p = 0.043), and both T2 relaxation time and ECV predicted troponin positivity (C-statistics: 0.71, p = 0.009; and 0.77, p = 0.006). Left ventricular end-diastolic and left atrial volumes were the strongest predictors of troponin positivity (C-statistics: 0.80, p = 0.001; and 0.82, p < 0.001). The increased T2 relaxation time and ECV and their significant correlation in the troponin-positive group suggest myocardial injury with oedema, while the non-ischaemic LGE could be due to myocardial fibrosis or acute necrosis. These CMR imaging biomarkers provide important clinical indices for risk stratification and prognostication in patients with hypertensive crisis.

Correlation of T1- to T2-weighted signal intensity ratio with T1- and T2-relaxation time and IDH mutation status in glioma

The current study aimed to test whether the ratio of T1-weighted to T2-weighted signal intensity (T1W/T2W ratio: rT1/T2) derived from conventional MRI could act as a surrogate relaxation time predictive of IDH mutation status in histologically lower-grade gliomas. Strong exponential correlations were found between rT1/T2 and each of T1- and T2-relaxation times in eight subjects (rT1/T2 = 1.63exp−0.0005T1-relax + 0.30 and rT1/T2 = 1.27exp−0.0081T2-relax + 0.48; R2 = 0.64 and 0.59, respectively). In a test cohort of 25 patients, mean rT1/T2 (mrT1/T2) was significantly higher in IDHwt tumors than in IDHmt tumors (p < 0.05) and the optimal cut-off of mrT1/T2 for discriminating IDHmt was 0.666–0.677, (AUC = 0.75, p < 0.05), which was validated in an external domestic cohort of 29 patients (AUC = 0.75, p = 0.02). However, this result was not validated in an external international cohort derived from TCIA/TCGA (AUC = 0.63, p = 0.08). The t-Distributed Stochastic Neighbor Embedding analysis revealed a greater diversity in image characteristics within the TCIA/TCGA cohort than in the two domestic cohorts. The failure of external validation in the TCIA/TCGA cohort could be attributed to its wider variety of original imaging characteristics.

Evaluation of the T2-weighted (T2W) adrenal MRI calculator to differentiate adrenal pheochromocytoma from lipid-poor adrenal adenoma

To evaluate the T2-weighted (T2W) MRI calculator to differentiate adrenal pheochromocytoma from lipid-poor adrenal adenoma. Twenty-nine consecutive pheochromocytomas resected between 2010 and 2019 were compared to 23 consecutive lipid-poor adrenal adenomas. Three blinded radiologists (R1, R2, R3) subjectively evaluated T2W signal intensity and heterogeneity and extracted T2W signal intensity ratio (SIR) and entropy. These values were imputed into a quantitative and qualitative T2W adrenal MRI calculator (logistic regression model encompassing T2W SIR + entropy and subjective SI [relative to renal cortex] and heterogeneity) using a predefined threshold to differentiate metastases from adenoma and accuracy derived by a 2 × 2 table analysis. Subjectively, pheochromocytomas were brighter (p < 0.001) and more heterogeneous (p < 0.001) for all three radiologists. Inter-observer agreement was fair-to-moderate for T2W signal intensity (K = 0.37-0.46) and fair for heterogeneity (K = 0.24-0.32). Pheochromocytoma had higher T2W-SI-ratio (p < 0.001) and entropy (p < 0.001) for all three readers. The quantitative calculator differentiated pheochromocytoma from adenoma with high sensitivity, specificity, and accuracy (100% [95% confidence intervals 88-100%], 87% [66-97%], and 94% [86-100%] R1; 93% [77-99%], 96% [78-100%], and 94% [88-100%] R2; 97% [82-100%], 96% [78-100%], and 96% [91-100% R3]). The qualitative calculator was specific with lower sensitivity and overall accuracy (48% [29-68%], 100% [85-100%], and 74% [65-83%] R1; 45% [26-64%], 100% [85-100%], and 72% [63-82%] R2; 59% [39-77%], 100% [85-100%], and 79% [70-88% R3]). T2W signal intensity and heterogeneity differ, subjectively and quantitatively, in pheochromocytoma compared to adenoma. Use of a quantitative T2W adrenal calculator which combines T2W signal intensity ratio and entropy was highly accurate to diagnose pheochromocytoma outperforming subjective analysis. • Pheochromocytomas have higher T2-weighted signal intensity and are more heterogeneous compared to lipid-poor adrenal adenomas evaluated subjectively and quantitatively. • The quantitative T2-weighted adrenal MRI calculator, a logistic regression model combining T2-weighted signal intensity ratio and entropy, is highly accurate for diagnosis of pheochromocytoma. • The qualitative T2-weighed adrenal MRI calculator had high specificity but lower sensitivity and overall accuracy compared to quantitative assessment and agreement was only fair-to-moderate.

Histopathologic correlation of pancreatic fibrosis with pancreatic magnetic resonance imaging quantitative metrics and Cambridge classification

To determine the correlation of the T1-weighted signal intensity ratio (T1 SIR, or T1 Score) and arterial-to-delayed venous enhancement ratio (ADV ratio) of the pancreas with pancreatic fibrosis on histopathology. Sixty consecutive adult CP patients who had an MRI/MRCP study prior to pancreatic surgery were analyzed. Three blinded observers measured T1 SIR of pancreas to spleen (T1 SIR p/s), pancreas-to-paraspinal muscle (T1 SIR p/m), ADV ratio, and Cambridge grade. Histopathologic grades were given by a gastrointestinal pathologist using Ammann's fibrosis score. Statistical analysis included Spearman's correlation coefficient of the T1 SIR, ADV ratio, Cambridge grade with the fibrosis score, and weighted kappa for interobserver agreement. The study population included 31 female and 29 male patients, with an average age of 52.1 (26-78years). Correlations between fibrosis score and T1 SIR p/s, T1 SIR p/m, and ADV ratio were ρ = - 0.54 (p = 0.0001), ρ = - 0.19 (p = 0.19), and ρ = - 0.39 (p = 0.003), respectively. The correlation of Cambridge grade with fibrosis score was ρ = 0.26 (p = 0.07). There was substantial interobserver agreement (weighted kappa) for T1 SIR p/s (0.78), T1 SIR p/m (0.71), and ADV ratio (0.64). T1 SIR p/s of ≤ 1.20 provided a sensitivity of 74% and specificity of 50% (AUC: 0.74), while ADV ratio of ≤ 1.10 provided a sensitivity of 75% and specificity of 55% (AUC: 0.68) to detect a fibrosis score of ≥ 6. There is a moderate negative correlation between the T1 Score (SIR p/s) and ADV ratio with pancreatic fibrosis and a substantial interobserver agreement. These parenchymal metrics show a higher correlation than the Cambridge grade.

The Utility of Multiparametric MRI or Difffferentiating Adrenal Adenomas from Adrenal Metastases

Purpose: To evaluate the possibility of multiparametric MRI in the differential diagnosis of benign adrenal adenomas and adrenal metastases.Material and methods: In our study we evaluated 27 adenomas and 13 adrenal metastases using MRI in 35 patients who underwent examination and treatment at the basis of the N.N. Blokhin National Research Center of Oncology during the follow-up period from 2019 to 2021. The following parameters were evaluated: contours, homogeneity (homogeneous and heterogeneous), T2-weighted SI ratio (isointensive, moderately hyperintensive or sharply hyperintensive) relative to muscle and spleen, signal intensity (SI) decrease on chemical-shift MRI, measurement of the chemical-shift SI index, adrenal-to-spleen SI ratio, areas under the ROC curve (AUC) for contrast-enhanced MRI, absolute and relative percentage wash-out. Sensitivity, specificity, and positive and negative predictive values were calculated. DWI with b-values 400 and 800 s/mm2 and ADCs imaging were measured in adrenal lesions.Results: Metastases were subjectively more heterogeneous than adenomas (76.9 % vs 63 % of cases, p = 0.0181). Adenomas had higher T2-weighted SI (average value = 228; range from 91 to 732) than metastases (average value = 331; range from 114 to 581), both quantitatively (p = 0.0326) and subjectively by visual assessment (p = 0.0171).According to the T1-WI out-of-phase data, a more intense MR signal was observed in metastases (average value 162; range from 102 to 242) compared with adenomas (average value = 74; range from 17 to 183) (p &lt; 0.0001), which was confirmed by normalization to muscle (p &lt; 0.0001) and spleen (p = 0.0002). Adrenal metastases were characterized by a significantly lower chemical shift index (average value = 3.8; range from –16.4 to 47.8; p &lt; 0.0001) compared with adenomas (average value 55.4; range from –4.2 to 85.5), and a higher chemical shift index in the ratio adrenal gland/spleen (p = 0.0079). There were no significant difference in the value of ADC-cards of adenomas and adrenal metastases. However, a higher level of SI on DWI at b = 800 s/ mm2 without normalization (p = 0.0262) and with normalization to muscle (p = 0.0064) and spleen (p = 0.0007) was evaluated in metastases, as well as on DWI at b = 400 s/mm2 with normalization for muscle (p = 0.0086) and spleen (p = 0.035). On native T1-WI FS, there was a lower level of SI revealed in adenomas compared to adrenal metastases (p = 0.0025), which was confirmed by normalization to the muscle (p = 0.0028) and spleen (p = 0.0035). In the venous and delayed phases of scanning the SI in adenomas was also lower than in metastases both without normalization (p = 0.0123 and p = 0.007, respectively), and with normalization to the muscle (p = 0.013 and p = 0.0011, respectively) and the spleen (p = 0.0084 and p = 0.0012, respectively). However, the SI in the arterial phase of scanning with and without normalization, the accumulation of MRCS in all phases of MRI scanning, the absolute and relative percentage wash-out of MRCS and the area under the MRCS accumulation curve in the groups had no statistically significant difference.

Evaluation of the effect of multiple administrations of gadopentetate dimeglumine or gadoterate meglumine on brain T1-weighted hyperintensity in pediatric patients.

Repeated administrations of linear gadolinium-based contrast media (GBCM) are associated with T1-weighted (T1-W) signal intensity change in brain structures. The purpose of this study was to compare different brain structures in children after unconfounded, repeated administrations of either a macrocyclic or linear GBCM. We performed a retrospective cohort study, identifying subjects with ≥5 unconfounded administrations of gadoterate meglumine. We matched subjects with repeated administrations of gadopentetate dimeglumine to the gadoterate meglumine arm based on the number of unconfounded GBCM administrations. Two reviewers drew regions of interest on 27 structures in and around the brain. We recorded demographic, modality and study parameters and evaluated them to determine whether they were associated with T1-W signal intensity (SI) changes. Linear mixed effects models evaluated the relationships between the number of GBCM doses and T1-W SI ratio. Finally, we identified differences in the rate of T1-W SI ratio change among individuals using a linear mixed effects model with random slope. We included a total of 52 patients (age range at first MRI: 6.0months to 17.1years), 26 in each arm. We detected a significant change in the T1-W SI ratio with repeated administrations of GBCM in one location in the gadoterate meglumine arm and in four locations in the gadopentetate dimeglumine arm. Patient gender and age were not associated with T1-W SI change. Modality vendor, imaging sequence and field strength were variably associated with a systematic difference in the ability to detect a T1-W SI change. Finally, linear mixed effects model with random slope showed that there were individual differences in the slope of SI change at various structures among individuals for both arms. This effect was present in more brain structures in the gadopentetate dimeglumine arm (14 vs. 8). There is a significant change in the T1-W SI ratio over time in multiple brain structures after repeated gadopentetate dimeglumine administrations. This effect was only seen in one ratio after repeated administrations of gadoterate meglumine. There are individual differences in the rate of change of SI ratios over time after repeated administration of gadopentetate dimeglumine and gadoterate meglumine, suggesting that individual differences are present.

The association between intracompartmental pressure and skeletal muscle recovery after tibial diaphyseal fractures: an ambispective cohort study

BackgroundDue to the special anatomy of the lower leg, tibial diaphyseal fracture causes increased intracompartmental pressure (ICP). Not only is this increased ICP the manifestation of skeletal muscle injury, but it induces further deterioration of the injury. The aim of this study was to assess the association between short-term ICP elevation and long-term skeletal muscle recovery after severe limb trauma.MethodsIn this single-center ambispective cohort study, we retrospectively screened and recruited a cohort of tibial diaphyseal fracture patients with integrated ICP data during the early post-traumatic period, and performed a prospective observational study to evaluate their skeletal muscle recovery through long-term follow-up and MR imaging after the removal of the implants. We analyzed the association between ICP elevation and skeletal muscle recovery using statistical methods.ResultsA total of 46 patients with healed fractures underwent intramedullary nail removal and MR imaging. The absolute values of the Pearson product-moment correlation coefficients between various ICP parameters and the cross-sectional area ratio (CSAR) ranged from 0.588 to 0.793, and the correlation coefficients between the ICP parameters and the average T2-weighted signal intensity ratio (T2SIR) varied from 0.566 to 0.775. Statistically significant associations were observed between the ICP parameters and the MR imaging parameters when simple linear regression analysis was performed. Among the ICP parameters, the accumulated ΔP (ΔP = diastolic blood pressure minus ICP) had the highest determination coefficient and explained 62.1% and 59.1% of the variance in CSAR and T2SIR, respectively.ConclusionsShort-term ICP elevation was associated with long-term skeletal muscle recovery following tibial diaphyseal fracture, especially for ICP data that integrated time factors.Level of evidenceLevel 3.

Utility of T2-weighted MRI to Differentiate Adrenal Metastases from Lipid-Poor Adrenal Adenomas.

To evaluate T2-weighted MRI features to differentiate adrenal metastases from lipid-poor adenomas. With institutional review board approval, this study retrospectively compared 40 consecutive patients (mean age, 66 years ± 10 [standard deviation]) with metastases to 23 patients (mean age, 60 years ± 15) with lipid-poor adenomas at 1.5- and 3-T MRI between June 2016 and March 2019. A blinded radiologist measured T2-weighted signal intensity (SI) ratio (SInodule/SIpsoas muscle), T2-weighted histogram features, and chemical shift SI index. Two blinded radiologists (radiologist 1 and radiologist 2) assessed T2-weighted SI and T2-weighted heterogeneity using five-point Likert scales. Subjectively, T2-weighted SI (P < .001 for radiologist 1 and radiologist 2) and T2-weighted heterogeneity (P < .001, for radiologist 1 and radiologist 2) were higher in metastases compared with adenomas when assessed by both radiologists. Agreement between the radiologists was substantial for T2-weighted SI (Cohen κ = 0.67) and T2-weighted heterogeneity (κ = 0.62). Metastases had higher T2-weighted SI ratio than adenomas (3.6 ± 1.7 [95% confidence interval {CI}: 0.2, 8.2] vs 2.2 ± 1.0 [95% CI: 0.6, 4.3], P < .001) and higher T2-weighted entropy (6.6 ± 0.6 [95% CI: 4.9, 7.5] vs 5.0 ± 0.8 [95% CI: 3.5, 6.6], P < .001). At multivariate analysis, T2-weighted entropy was the best differentiating feature (P < .001). Chemical shift SI index did not differ between metastases and adenomas (P = .748). Area under the receiver operating characteristic curve (AUC) for T2-weighted SI ratio and T2-weighted entropy were 0.76 (95% CI: 0.64, 0.88) and 0.94 (95% CI: 0.88, 0.99). The logistic regression model combining T2-weighted SI ratio with T2-weighted entropy yielded AUC of 0.95 (95% CI: 0.91, 0.99) and did not differ compared with T2-weighted entropy alone (P = .268). There was no difference in logistic regression model accuracy comparing the data by either field strength, 1.5- or 3-T MRI (P > .05). Logistic regression models combining T2-weighted SI and T2-weighted heterogeneity can differentiate metastases from lipid-poor adenomas. Validation of these preliminary results is required.Keywords: Adrenal, MR-Imaging, UrinarySupplemental material is available for this article.© RSNA, 2020.

Validation of threshold values for pancreas thickness and T1-weighted signal intensity ratio in the pediatric pancreas.

Pancreas atrophy and the loss of T1-weighted signal intensity by magnetic resonance imaging (MRI) are findings of chronic pancreatitis. The purpose of this study was to test published normal values and cutoffs for pancreas thickness and the pancreas:spleen T1-weighted signal intensity ratio in children without pancreatic disease. This was a secondary analysis of prospectively collected MRI data for 50 children (range: 6.3-15.9years; 27 female) with no history of pancreatic disease. Two observers (R1, R2) measured linear pancreas thickness on axial T1-weighted, fat-saturated gradient recalled echo images and placed regions of interest in the pancreas and spleen to calculate the T1-weighted signal intensity ratio. Measurements were compared to published pediatric normal values (computed tomography [CT], ultrasound [US]) and adult cutoffs (CT, MRI). Compared to published pediatric values for CT, 68% (R1: 34/50) or 40% (R2: 22/50) of participants had ≥1 pancreas segment with thickness below the normal range. No participant had a thickness value below the normal range published for US. Compared to cutoff values in adults, 84% (R1: 42/50) or 80% (R2: 40/50) of participants met the criteria for pancreas atrophy. Mean T1-weighted signal intensity ratio was 1.33±0.15 (R1) and 1.32±0.16 (R2). Twelve (R1: 24.5% of 49) or 11/49 (R2: 22.4%) participants had a T1-weighted signal intensity ratio below the threshold associated with exocrine insufficiency in adults. Previously defined thresholds for pancreas thickness and pancreas:spleen T1-weighted signal intensity ratio appear too restrictive for a pediatric population. Further study is needed to define optimal quantitative metrics for findings of chronic pancreatitis in children.

MR imaging of palatine gland lesion-associated IgG4-related disease: a preliminary study.

The purpose of this study was to present the novel MRI findings of palatine gland lesion-associated IgG4-related disease (PGL-IgG4-RD) and to compare the imaging features with those in normal individuals. We retrospectively evaluated the MRI scans of 12 patients with PGL-IgG4-RD and 12 control individuals. We measured the thickness of the palatal regions and calculated the T2-weighted signal intensity ratio of palatal regions to cerebral white matter (HWR) and compared them between the PGL-IgG4-RD and control groups. In univariate analysis, the HWR of the palatal regions on T2-weighted imaging was smaller in the PGL-IgG4-RD group than in the control group (average = 1.2 vs. 1.9, p < 0.001). The palate thickness in patients with PGL-IgG4-RD was significantly greater than that in controls (average = 12 vs 6mm, p < 0.001). The cut-off value of the between-group palate thickness on coronal MRI was 8mm. The thickening of the palatal regions seen with low signal intensity on T2-weighted imaging may be a characteristic imaging feature of PGL-IgG4-RD. Such findings will be useful for the timely diagnosis and subsequent treatment planning of IgG4-RDHP.

Multifidus Muscle Changes After Biportal Endoscopic Spinal Surgery: Magnetic Resonance Imaging Evaluation

We used magnetic resonance imaging (MRI) to assess the radiological status of the multifidus muscles (MFMs) after biportal endoscopic spinal surgery (BESS) and evaluated the extent of MFM injury and atrophy. A total of 88 patients who had met the inclusion and exclusion criteria were enrolled in the present study. T2-weighted signal intensity MRI was performed 3 times: preoperatively, immediately postoperatively, and at the final follow-up examination. We measured the cross-sectional area of the MFM on both sides (ipsilaterally and contralaterally) and recorded the operative times. The association between the interval from surgery to the final follow-up MRI and changes in the MFMs and between the operative time and changes in the MFMs were analyzed. For the group comparisons, the patients were divided into 3 groups according to the follow-up interval. Group 1 was followed up within 2 weeks, group 2 within 2-4 weeks, and group 3 after 4 weeks. The MFM changes were recorded. The operative time correlated significantly with the percentage of change in the T2-weighted signal intensity ratio (SIR) for both sides (P < 0.01). At the final follow-up examination, the SIR of the ipsilateral side had decreased in group 3 (P= 0.002). The percentage of change in the SIR was smallest in group 3 (P= 0.004). The MFM change on MRI after BESS became significant on both sides as the operative time increased. However, the change showed a tendency to reverse within several months, and no substantial change in the MFM cross-sectional area was found. We have concluded that MFM changes after BESS might correlate with an increased operative time but will resolve over time.

Magnetic Resonance Imaging as a Valid Noninvasive Tool for the Assessment of Pancreatic Fibrosis.

The aim of this study was to evaluate the utility of magnetic resonance imaging (MRI) for the noninvasive assessment of pancreatic fibrosis (PF). Fifty-two patients who underwent surgical resection of the pancreas, histological examination of resection margins, preoperative abdominal MRI, and fecal elastase-1 test were enrolled in the study. Pancreatic tissue was identified on the MRI T1-, T2-, and diffusion-weighted imaging sequences. Apparent diffusion coefficient (ADC) was measured at the expected resection margin of the pancreas. There was a significant negative correlation between the ADC mean and histologically determined PF (r = -0.752, P = 0.001). For equal to or greater than 25% of PF, the ADC cutoff value was 1.331 or less, with a sensitivity of 77% and specificity of 88%. The unenhanced T1-weighted signal intensity ratio (T1SI) cutoff value was 172.1 or less. For equal to or greater than 50% of PF, the ADC cutoff value was 1.316 or less with a sensitivity of 85% and specificity of 88%. The highest sensitivity was obtained by combining ADC and T1SI values. Combining both the ADC and T1SI measurement allows the detection of early PF with good sensitivity and specificity. Magnetic resonance imaging has the advantage of being noninvasive and widely used in the clinical setting, thus making our results easily transferable to routine clinical practice.

Cardiac Magnetic Resonance Quantitative Tissue Markers in the Clinical Application Value for the Diagnosis of Acute Myocarditis

Objectives: To determine the value of cardiac magnetic resonance (CMR) quantitative tissue markers in the diagnosis of acute myocarditis, compared with the traditional Lake-Louise criteria (LLC). Methods: Totally 35 cases of patients diagnosed as acute myocarditis in Beijing Anzhen Hospital and 35 healthy volunteers were enrolled in our study, from May 2014 to August 2016. CMR protocol included quantitative assessment of T1 relaxation times using modified Look-Locker inversion recovery (MOLLI), extracellular volume fraction (ECV), T2 relaxation times. Established Lake-Louise criteria (LLC) consisting of T2-weighted signal intensity ratio (T2-ratio), early gadolinium enhancement ratio (EGEr), and late gadolinium enhancement (LGE) were assessed. Receiver operating characteristics analysis was performed to compare diagnostic performance. Results: T2-ratio (1.85±0.21 vs. 1.58±0.15; P = 0.002) and EGEr (3.87±1.62 vs. 2.15±1.36; P =0.024) were significantly higher in myocarditis subjects than in control subjects. Non-ischemic LGE was found in 27/35 (77.1%) of all myocarditis patients. Regional myocardial edema was found in 23/35 (65.7%) of all myocarditis patients. Myocardial T1 and T2 relaxation times and ECV were significantly prolonged in the myocarditis group compared with the control group (T1 native relaxation time: 1310±62 vs. 1247±27 ms, T2 native relaxation time: 65.46±8.49 vs. 55.17±3.59 ms; ECV: 34.47±8.52 vs. 27.68±5.82, P &lt; 0.001, respectively). Areas under the curve of native T1 (0.94) and T2 relaxation times (0.91) were higher compared with those of the other CMR parameters (T2-ratio: 0.73, EGEr: 0.72, LGE: 0.88, LLC: 0.90, ECV: 0.79). Combined with LGE, each native mapping technique outperformed the diagnostic performance of LLC (P &lt; 0.01, respectively). A combination of native parameters (T1, T2 relaxation times) significantly increased the diagnostic performance of CMR compared with LLC without need of contrast media application (0.99 vs. 0.90; P &lt; 0.05). Conclusion: CMR quantitative tissue markers has good diagnostic efficiency for acute myocarditis, it may be potential to replace the Lake-Louise criteria in the future in patients with contraindications for the use of gadolinium-based contrast agents.

Multiple Administrations of Gadobutrol in the Pediatric Brain: No Change in T1 Signal at MRI.

Purpose To determine whether multiple doses of gadobutrol increase the T1 signal intensity in the brains of children. Materials and Methods This retrospective imaging study evaluated 91 children (median age, 5.4 years; age range, 0-17 years) with brain tumors who underwent five or more MR brain examinations at a single institution. A subgroup of 46 patients received five or more administrations of gadobutrol (0.1 mmol/kg) and underwent follow-up MRI. T1 signal intensity in the globus pallidus and dentate nucleus was measured at the first to sixth unenhanced MR brain examination in these children. Globus pallidus-to-corpus callosum and dentate nucleus-to-corpus callosum signal intensity ratios were analyzed by linear mixed-effect analysis. Subgroup analysis was performed for six children who underwent 14 or more administrations of gadobutrol. Results The globus pallidus-to-corpus callosum ratio increased with patient age (absolute change, 0.0052 per year; 95% confidence interval: 0.0033, 0.0071; P < .0001). There was no change in the dentate nucleus-to-corpus callosum ratio with age (P = .30). Among 46 children who received five or more doses of gadobutrol (median dose, 11 mL; range, 3.9-31 mL), there was no change in signal intensity ratio of the globus pallidus (P = .17) or dentate nucleus (P = .44). Among six children who underwent more than 14 administrations of gadobutrol (median dose, 64 mL; range, 40-91 mL) there was no change in signal intensity ratio of the globus pallidus (P = .15) or dentate nucleus (P = .50). Conclusion No increase in T1-weighted signal intensity ratio was observed in the globus pallidus or dentate nucleus after the administration of at least five doses of gadobutrol. © RSNA, 2018 Online supplemental material is available for this article.

Multifidus Muscle Atrophy Not Observed Following Two-segment Anterior Interbody Fusion: A Rabbit Model Study With a 12-Month Follow-up.

Experimental study evaluated magnetic resonance imaging (MRI) and histologic changes in the multifidus muscle after anterior spinal fusion. To determine the effect of spinal fusion on the multifidus muscle in an anterior rabbit model through the use of MRI and histologic evaluation. Retraction and splitting approach are known to be important factors in postoperative injury and atrophy of the multifidus muscle. The effect and possible mechanism of spinal fusion as an independent factor remains unknown. Thirty-six New Zealand white rabbits were divided into two groups. Animals in the fusion group underwent two-level anterior spinal fusion whereas those in the control group underwent similar surgery without spinal fusion. The status of the multifidus muscle was evaluated with MRI and histological analysis at preoperative, 3 weeks, 6 weeks, 3 months, 6 months, and 12 months postoperatively. All rabbits in the fusion group achieved solid fusion. The mean T1-weighted and T2-weighted signal intensity ratios of gross multifidus to psoas muscles were all approximately 1.0 postoperatively, with no remarkable difference between the groups. The mean lesser diameter of myofibrils in either group did not significantly differ between the preoperative and postoperative specimens. There was no significant fibrotic change or fatty degeneration for either group. Decrease in acetylcholine activity or granular degeneration of the neuromuscular junction were not observed, and normal shape and size were found in nearly all samples at all time points in both groups (P > 0.05). After two-segment anterior spinal fusion, multifidus atrophy was not observed throughout a 12-month follow up. The rabbit model of anterior fusion is better suited to study the effect of fusion alone on the status of the multifidus muscle. 3.

Evaluation of T1-Weighted MRI to Detect Intratumoral Hemorrhage Within Papillary Renal Cell Carcinoma as a Feature Differentiating From Angiomyolipoma Without Visible Fat.

The objective of the present study is to determine whether hemorrhage within papillary renal cell carcinoma (RCC) can be detected using T1-weighted MRI and to ascertain whether it can be used to differentiate papillary RCC from angiomyolipoma (AML) without visible fat. A retrospective case-control study compared 11 AMLs without visible fat with 58 papillary RCCs smaller than 5 cm that were evaluated using MRI between 2003 and 2015. Two blinded radiologists subjectively evaluated MR images to identify the presence of intratumoral hemorrhage on the basis of a decrease in signal intensity (SI) on in-phase, compared with opposed-phase, chemical-shift MRI and also on the basis of the SI of the lesion compared with that of the renal cortex on fat-suppressed T1-weighted MRI. A third radiologist established consensus and measured the ratio of the SI of the lesion to that of the renal cortex (hereafter referred to as the "SI ratio") on T2-weighted MRI; the SI loss index, as calculated using the equation [(SItumorIP - SItumorOP) / SItumorOP] × 100, where IP denotes the in-phase image and OP denotes the opposed-phase image; and the SI ratio on fat-suppressed T1-weighted MRI. Analyses were performed using tests of association and ROCs. When AMLs without visible fat were compared with papillary RCCs, no statistically significant difference in the T2-weighted SI ratio was noted (p = 0.08). Papillary RCCs had a lower mean (± SD) SI loss index (-3.7% ± 17.3%; range, -51.3% to 31.3%) than did AMLs without visible fat (37.8% ± 76.1%; range, -15.6% to 184.4%) (p < 0.001). A mean SI loss index of less than -16% resulted in an AUC of 0.71 (95% CI, 0.52-0.91), with a sensitivity and specificity of 22.8% and 100%, respectively, for the diagnosis of papillary RCC. After consensus review, none of the AMLs without visible fat and 16 of the 58 papillary RCCs (27.6%) were found to have a decrease in SI on subjective analysis (p = 0.06, κ = 0.60). Between groups, no differences were noted in the SI ratio on fat-suppressed T1-weighted MRI (p = 0.58) or in the SI observed on subjective analysis of fat-suppressed T1-weighted MRI (p = 0.20, κ = 0.48). The presence of intratumoral hemorrhage within papillary RCC is a specific feature that differentiates papillary RCCs from AMLs without visible fat. Subjective analysis may be more clinically appropriate than chemical-shift MRI because of limitations in the quantitative measurement of T2* signal with the use of chemical-shift MRI.

Comparison of Quantitative MRI and CT Washout Analysis for Differentiation of Adrenal Pheochromocytoma From Adrenal Adenoma.

The purpose of this study was to use quantitative analysis to assess MRI and washout CT in the diagnosis of pheochromocytoma versus adenoma. Thirty-four pheochromocytomas (washout CT, 5; MRI, 24; both MRI and CT, 5) resected between 2003 and 2014 were compared with 39 consecutive adenomas (washout CT, 9; MRI, 29; both MRI and CT, 1). A blinded radiologist measured unenhanced attenuation, 70-second peak CT enhancement, 15-minute relative and absolute percentage CT washout, chemical-shift signal intensity index, adrenal-to-spleen signal intensity ratio, T2-weighted signal intensity ratio, and AUC of the contrast-enhanced MRI curve. Comparisons between groups were performed with multivariate and ROC analyses. There was no difference in age or sex between the groups (p > 0.05). For CT, pheochromocytomas were larger (4.2 ± 2.5 [SD] vs 2.3 ± 0.9 mm; p = 0.02) and had higher unenhanced attenuation (35.7 ± 6.8 HU [range, 24-48 HU] vs 14.0 ± 20.9 HU [range, -19 to 52 HU]; p = 0.002), greater 70-second peak CT enhancement (92.8 ± 31.1 HU [range, 41.0-143.1 HU] vs 82.6 ± 29.9 HU [range, 50.0-139.0 HU ]; p = 0.01), lower relative washout CT (21.7 ± 24.7 [range, -29.3 to 53.7] vs 65.3 ± 22.3 [range, 32.9-115.3]; p = 0.002), and lower absolute washout CT (31.9 ± 42.8 [range, -70.6 to 70.2] vs 76.9 ± 10.3 [range, 60.3-89.6]; p = 0.001). Thirty percent (3/10) of pheochromocytomas had absolute CT washout in the adenoma range (> 60%). For MRI, pheochromocytomas were larger (5.0 ± 4.2 vs 2.0 ± 0.7 mm; p = 0.003) and had a lower chemical-shift signal intensity index and higher adrenal-to-spleen signal intensity ratio (-3.5% ± 14.3% [range, -56.3% to 12.2%] and 1.1% ± 0.1% [range, 0.9-1.3%] vs 47.3% ± 27.8% [range, -9.4% to 86.0%] and 0.51% ± 0.27% [range, 0.13-1.1%]) (p < 0.001) and higher T2-weighted signal intensity ratio (4.4 ± 2.4 vs 1.8 ± 0.8; p < 0.001). There was no statistically significant difference in contrast-enhanced MRI AUC (288.9 ± 265.3 vs 276.2 ± 129.9 seconds; p = 0.96). The ROC AUC for T2-weighted signal intensity ratio was 0.91 with values greater than 3.8 diagnostic of pheochromocytoma. In this study, the presence of intracellular lipid on unenhanced CT or chemical-shift MR images was diagnostic of adrenal adenoma. Elevated T2-weighted signal intensity ratio was specific for pheochromocytoma but lacked sensitivity. There was overlap in all other MRI and CT washout parameters.

Pancreatic Steatosis and Fibrosis: Quantitative Assessment with Preoperative Multiparametric MR Imaging.

To evaluate the diagnostic performance of multiparametric pancreatic magnetic resonance (MR) imaging, including the T2*-corrected Dixon technique and intravoxel incoherent motion (IVIM) diffusion-weighted (DW) imaging, in the quantification of pancreatic steatosis and fibrosis, with histologic analysis as the reference standard, and to determine the relationship between MR parameters and postoperative pancreatic fistula. This retrospective study was approved by the institutional review board, and the informed consent requirement was waived. A total of 165 patients (93 men, 72 women; mean age, 62 years) underwent preoperative 3-T MR imaging and subsequent pancreatectomy (interval, 0-77 days). Fat fractions, IVIM DW imaging parameters (true diffusion coefficient [D], pseudodiffusion coefficient [D*], and perfusion fraction [f]), pancreas-to-muscle signal intensity ratios on unenhanced T1-weighted images, and pancreatic duct sizes were compared with the fat fractions and fibrosis degrees (F0-F3) of specimens. In 95 patients who underwent pancreatoenteric anastomosis, MR parameters were compared between groups with clinically relevant postoperative pancreatic fistula and those without. The relationship between postoperative pancreatic fistula and MR parameters was evaluated by using logistic regression analysis. Fat fractions at MR imaging showed a moderate relationship with histologic findings (r = 0.71; 95% confidence interval: 0.63, 0.78). Patients with advanced fibrosis (F2-F3) had lower D*([39.72 ± 13.64] ×10(-3)mm(2)/sec vs [32.50 ± 13.09] ×10(-3)mm(2)/sec [mean ± standard deviation], P = .004), f (29.77% ± 8.51 vs 20.82% ± 8.66, P < .001), and unenhanced T1-weighted signal intensity ratio (1.43 ± 0.26 vs 1.21 ± 0.30, P < .001) than did patients with F0-F1 disease. Clinically relevant fistula developed in 14 (15%) of 95 patients, and f was significantly associated with postoperative pancreatic fistula (odds ratio, 1.17; 95% confidence interval: 1.05, 1.30). Multiparametric MR imaging of the pancreas, including imaging with the T2*-corrected Dixon technique and IVIM DW imaging, may yield quantitative information regarding pancreatic steatosis and fibrosis, and f was shown to be significantly associated with postoperative pancreatic fistulas.

T1 mapping for assessment of myocardial injury and microvascular obstruction at one week post myocardial infarction

ObjectivesTo compare 3T T1 mapping to conventional T2-weighted (T2W) imaging for delineating myocardial oedema one week after ST-elevation myocardial infarction (STEMI), and to explore the confounding effects of microvascular obstruction (MVO) on each technique. MethodsT2W spectral attenuated inversion recovery and native T1 mapping were applied in 10 healthy volunteers and 62 STEMI patients, and late gadolinium enhancement was included for infarct localisation at 1 week and at 6 months post-STEMI. Segmental T1 values and T2W signal intensity ratios were calculated; oedema volumes and salvage indices were determined in patients using image thresholding—a receiver operator characteristic (ROC) derived T1 threshold, and a 2SD T2W threshold; and the results were compared between patients with/without MVO (n=35/27). ResultsNative T1 mapping delineated oedema with significantly better discriminatory power than T2W—as indicated by ROC analysis (area-under-the-curve, AUC=0.89 versus 0.83, p=0.009; and sensitivity/specificity=83/83% versus 73/73%). The optimal ROC threshold derived for T1 mapping was 1241ms, which gave significantly larger oedema volumes than 2SD T2W (p=0.006); with this threshold, patients with and without MVO showed similar oedema volumes, but patients with MVO had significantly poorer salvage indices (p<0.05) than those without. Neither method was significantly affected by MVO, the volume of which was seen to increase exponentially with infarct size. ConclusionsNative T1 mapping at 3T can delineate oedema one week post-STEMI, showing larger oedema volumes and better discriminatory power than T2W imaging, and it is suitable for quantitative thresholding. Both techniques are robust against MVO-related magnetic susceptibility.

Incremental value of quantitative CMR including parametric mapping for the diagnosis of acute myocarditis.

Cardiac magnetic resonance (CMR) can visualize inflammatory tissue changes in acute myocarditis. Several quantitative image-derived parameters have been described to enhance the diagnostic value of CMR, but no direct comparison of these techniques is available. A total of 34 patients with suspected acute myocarditis and 50 control subjects underwent CMR. CMR protocol included quantitative assessment of T1 relaxation times using modified Look-Locker inversion recovery (MOLLI) and shortened MOLLI (ShMOLLI) acquisition schemes, extracellular volume fraction (ECV), T2 relaxation times, and longitudinal strain. Established Lake-Louise criteria (LLC) consisting of T2-weighted signal intensity ratio (T2-ratio), early gadolinium enhancement ratio (EGEr), and late gadolinium enhancement (LGE) were assessed. Receiver operating characteristics analysis was performed to compare diagnostic performance. Areas under the curve of native T1 (MOLLI: 0.95; ShMOLLI: 0.92) and T2 relaxation times (0.92) were higher compared with those of the other CMR parameters (T2-ratio: 0.71, EGEr: 0.71, LGE: 0.87, LLC: 0.90, ECV MOLLI: 0.77, ECV ShMOLLI: 0.80, longitudinal strain: 0.83). Combined with LGE, each native mapping technique outperformed the diagnostic performance of LLC (P < 0.01, respectively). A combination of native parameters (T1, T2, and longitudinal strain) significantly increased the diagnostic performance of CMR compared with LLC without need of contrast media application (0.99 vs. 0.90; P = 0.008). In patients suspected of having acute myocarditis, diagnostic performance of CMR can be improved by implementation of quantitative CMR parameters. Especially, native mapping techniques have the potential to replace current LLC. CLINICALTRIALS. NCT02299856.