Detecting lymph node metastasis of esophageal cancer on dual-energy computed tomography.

BACKGROUND: Using conventional computed tomography (CT), the accurate diagnosis of lymph node (LN) metastasis of esophageal cancer is difficult. PURPOSE: To examine dual-energy CT parameters to predict LN metastasis preoperatively in patients with esophageal cancer. MATERIAL AND METHODS: Twenty-six consecutive patients who underwent dual-energy CT before an esophageal cancer surgery (19 patients with LN metastases) were analyzed. The included LNs had a short-axis diameter of ≥4 mm and were confirmed to be resected on postoperative CT. Their short-axis diameter, CT value, iodine concentration (IC), and fat fraction were measured on early- and late-phase contrast-enhanced dual-energy CT images and compared between pathologically confirmed metastatic and non-metastatic LNs. RESULTS: In total, 51 LNs (34 metastatic and 17 non-metastatic) were included. In the early phase, IC and fat fraction were significantly lower in the metastatic than in the non-metastatic LNs (IC = 1.6 mg/mL vs. 2.2 mg/mL; fat fraction = 20.3% vs. 32.5%; both P < 0.05). Furthermore, in the late phase, IC and fat fraction were significantly lower in the metastatic than in the non-metastatic LNs (IC = 2.0 mg/mL vs. 3.0 mg/mL; fat fraction = 20.4% vs. 33.0%; both P < 0.05). Fat fraction exhibited accuracies of 82.4% and 78.4% on early- and late-phase images, respectively. Conversely, short-axis diameter and CT value on both early- and late-phase images were not significantly different between the metastatic and non-metastatic LNs (P > 0.05). CONCLUSION: Using dual-energy CT images, IC and fat fraction are useful for diagnosing LN metastasis in patients with esophageal cancer.

Comparison of Predictive Values of Magnetic Resonance Biomarkers Based on Scan Timing in Neonatal Encephalopathy Following Therapeutic Hypothermia.

OBJECTIVE: To determine the optimal quantitative magnetic resonance (MR) biomarker in neonatal encephalopathy following therapeutic hypothermia based on scan timing. STUDY DESIGN: This retrospective study included 98 neonates (35-41 weeks of gestation) with neonatal encephalopathy, who underwent therapeutic hypothermia; diffusion-weighted imaging and proton MR spectroscopy were performed at 24-96 hours (n = 56) and 7-14 days (n = 92) after birth, respectively, to estimate apparent diffusion coefficient (ADC) values, N-acetylaspartate and N-acetylaspartylglutamate (tNAA), lactate, and choline concentrations, and lactate/tNAA, tNAA/choline ratios in the deep gray matter. Adverse outcomes included death or neurodevelopmental impairment at 18-22 months of age. We used receiver operating characteristic curves to examine the prognostic accuracy of each MR biomarker. RESULTS: Deep gray matter tNAA concentrations showed the best prognostic value, with an area under the curve (AUC) of 0.97 and 1.00 at 24-96 hours and 7-14 days after birth, respectively. At 24-96 hours of age, ADC values, lactate concentrations, and lactate/tNAA ratios showed prognostic value with AUCs of 0.90, 0.95, and 0.97, respectively. At 7-14 days of age, the AUCs of ADC values, lactate, and lactate/tNAA ratios were 0.61, 0.67, and 0.80, respectively; these were lower than those at 24-96 hours of age. CONCLUSIONS: During the first 2 weeks of life, the deep gray matter tNAA concentration was the most accurate quantitative MR biomarker. Although ADC values, lactate levels, and lactate/tNAA ratios also showed high prognostic value during 24-96 hours of life, only tNAA retained high prognostic value in the second week of life.

Clinical impacts of magnetic resonance thoracic ductography on preventing postoperative chylothorax after thoracoscopic esophagectomy for esophageal cancer.

PURPOSE: The study aimed to determine whether magnetic resonance thoracic ductography (MRTD) is useful for preventing injury to the thoracic duct (TD) during thoracoscopic esophagectomy and for reducing the incidence of postoperative chylothorax. MATERIALS AND METHOD: A total of 389 patients underwent thoracoscopic esophagectomy between September 2009 and February 2019 in Tokai University Hospital. Of them, we evaluated 228 patients who underwent preoperative MRTD (MRTD group) using Adachi's classification and our novel classification (Tokai classification). Then, the clinicopathological factors of the MRTD group (n = 228) were compared with those of the non-MRTD group (n = 161), and comparative analyses were conducted after propensity score matching (PSM). RESULTS: The TD could be visualized by MRTD in 228 patients. The MRTD findings were divided into 9 classifications including normal findings and abnormal TD findings (Adachi classification vs Tokai classification; 5.3% vs 16.2%). After PSM, both groups consisted of 128 patients. The rate of postoperative chylothorax after thoracoscopic esophagectomy was significantly lower in the MRTD group (0.8%) than in the non-MRTD group (6.3%) (p = 0.036). In the multivariate analysis for risk factors for chylothorax, the independent prognostic factors were preoperative therapy and the presence of MRTD. CONCLUSIONS: This study revealed that MRTD was useful for preventing of chylothorax after thoracoscopic esophagectomy for esophageal cancer.

Usefulness of prone-position computed tomography as preoperative simulation prior to thoracoscopic esophagectomy for thoracic esophageal cancer.

PURPOSE: The study aimed to evaluate the usefulness of prone-position computed tomography (CT) for predicting relevant thoracic procedure outcomes in minimally invasive esophagectomy (MIE) for thoracic esophageal cancer. MATERIALS AND METHODS: A total of 59 patients underwent esophagectomy between May 2019 and December 2020 in Tokai University Hospital. Preoperative CT imaging was conducted with the patient in both the supine and prone positions, and the magnitude of change in the intramediastinal space was calculated. In the 56 patients (94.9%) who had undergone MIE, the effects of such a difference on the surgical outcomes were analyzed. RESULTS: A significant correlation of the magnitude of change in VE (distance between ventral aspect of the vertebral body and the midpoint of the esophagus) with the surgical outcome was revealed in the 17 patients (30.4%) in whom the magnitude of change in VE was over the 75th percentile. That is, in this subgroup, the magnitude of change in VE showed a negative correlation with the thoracic operation time (rs = - 0.57, p = 0.01) and blood loss during the thoracic procedure (rs = - 0.46, p = 0.01). Multivariate analysis identified a magnitude of change in VE ≥ 9 mm (OR = 0.14, p = 0.03) as an independent risk factor for postoperative pneumonia. CONCLUSIONS: This study indicates that preoperative prone-position CT imaging is useful for predicting the level of ease or difficulty of securing an adequate operative field, surgical outcomes, and the risk of postoperative pneumonia in MIE.

Visibility of bronchial arteries using virtual and advanced virtual monoenergetic imaging.

BACKGROUND: The utility of virtual monoenergetic imaging (VMI) for fine arteries has not been well clarified. PURPOSE: To assess bronchial artery visualization using VMI and noise-optimized advanced VMI (VMI+). MATERIAL AND METHODS: Eighty-seven patients with esophageal cancer underwent computed tomography (CT) using a third-generation dual-source system before surgery. Tube voltages were set to 90 kVp and 150 kVp, respectively. Images were reconstructed using VMI and VMI+ with energy levels of 40-120 keV (in 10-keV increments); composite images equivalent to CT images at 105 kVp were also generated. The CT attenuation value and contrast-to-noise ratio (CNR) of bronchial arteries using VMI and VMI+ were compared with those obtained using composite imaging. Two radiologists subjectively analyzed bronchial artery visualization with reference to the composite image. RESULTS: CT attenuation values for bronchial arteries using VMI at 40-60 keV and VMI+ at 40 keV and 50 keV were significantly higher than those obtained using composite imaging (P < 0.05). CNR using VMI at 40-60 keV was significantly higher than that obtained using composite imaging (P < 0.05), whereas no differences were noted for values obtained using composite imaging between VMI+ at 40 keV and 50 keV. In the subjective analysis, VMI at 40 keV and 50 keV yielded significantly better visibility of bronchial arteries than VMI+ (P < 0.05). CONCLUSION: VMI and VMI+ at low voltages (40-50 keV) may be useful for bronchial artery visualization. VMI+ may be less effective for fine vessels as bronchial artery visualization.

Magnetic resonance thoracic ductography assessment of serial changes in the thoracic duct after the intake of a fatty meal.

The thoracic duct, a terminal lymph vessel, is thought to dilate after the intake of a fatty meal. However, this physiological change has not been well explored in vivo. Therefore, the present study aimed to assess serial changes in the thoracic duct after the intake of a fatty meal using magnetic resonance thoracic ductography (MRTD). Eight healthy volunteers were subjected to one MRTD scan before a fatty meal and eight serial MRTD scans every hour thereafter. The cross-sectional areas of the thoracic duct were estimated using MRTD measurements of the diameters of the thoracic duct at the upper edge of the aortic arch, the tracheal bifurcation, the mid-point between the tracheal bifurcation and the left part of the diaphragm and the left part of the diaphragm. The change-rates in these areas were calculated before and after the fatty meal intake, and the maximal change-rate and timing of its achievement were determined for each subject. The summed change-rates in the four portions of the thoracic duct ranged from -40.1 to 81.3%, with maximal change-rates for each subject ranging from 22.8 to 81.3% (mean, 50.4%). Although individual variations were observed, most subjects (88.9%) exhibited a maximal change-rate at 4-6 h after meal intake, with subsequent decreases at 7-8 h. In conclusion, MRTD revealed a tendency toward thoracic duct enlargement at 4-6 h after the intake of a fatty meal, followed by contraction.

Clinical Significance of New Magnetic Resonance Thoracic Ductography Before Thoracoscopic Esophagectomy for Esophageal Cancer.

BACKGROUND: Preoperative simulation of the thoracic duct using magnetic resonance thoracic ductography (MRTD) would enable a safe lymph node dissection near the thoracic duct and the prevention of chylothorax after an esophagectomy. The aim of this study was to determine whether MRTD is useful for preventing injury to the thoracic duct during surgery and for reducing the incidence of chylothorax after surgery. METHODS: We evaluated 130 patients who underwent preoperative MRTD followed by a thoracoscopic esophagectomy for the treatment of thoracic esophageal cancer between August 2014 and April 2017 (MRTD group). These patients were then compared with 160 patients with esophageal cancer who underwent a thoracoscopic esophagectomy without preoperative MRTD (non-MRTD group). RESULTS: Four patients in the non-MRTD group developed Type IIIB chylothorax (International Consensus on Standardization), while none of the patients in the MRTD group developed Type III chylothorax. Some type of abnormal finding was found during MRTD in 24 patients (18.5%). Among them, 13 patients (10.0%) exhibited abnormal divergence, which was the most frequent finding, followed by 5 patients (3.8%) with window formation and 2 patients (1.5%) with stitch formation. CONCLUSIONS: The present study revealed the frequencies of abnormal findings of the thoracic duct and of patients with false-negative MRTD findings. Injury to the thoracic duct can be avoided through the use of appropriate care during procedures performed in patients with abnormal findings on preoperative MRTD.

Characteristic phase distribution in the white matter of infants on phase difference enhanced imaging.

BACKGROUND AND PURPOSE: The infantile brain is continuously undergoing development. Non-invasive methods to assess the neurological development of infants are important for the early detection of abnormalities. Some microstructures in the brain have been demonstrated via phase difference-enhanced imaging (PADRE), which may reflect myelin-related microstructures. We aimed to assess the white matter (WM) signal distribution in infants using PADRE and compared it with that using T1-weighted images (T1WI) and diffusion tensor imaging (DTI) on magnetic resonance imaging (MRI). MATERIALS AND METHOD: This study included 18 infants (postmenstrual age at MRI, 37-40 weeks) without abnormal findings on MRI. Signal distribution using T1WI, a fractional anisotropy (FA) map and PADRE was assessed regarding the following intraparenchymal structures: the optic radiation (OR), internal capsule (IC), corpus callosum, corticospinal tract (CST), semiovale center and subcortical regions. RESULTS: We found that the signal distribution was significantly different (P<0.001) with a relatively large signal change found at the IC and CST across the three imaging methods. Signal changes were also greater at the OR and rolandic subcortical WM on PADRE, whereas these were smaller on T1WI and FA. CONCLUSION: PADRE demonstrated a characteristic phase shift distribution in infantile WM, which was different from that observed on T1WI and FA maps, and may demonstrate the developing myelin-related structures. PADRE can be a unique indicator of infantile brain development.

Visualization of the airway in infants with MRI using pointwise encoding time reduction with radial acquisition (PETRA).

PURPOSE: To assess airway visibility in infants using pointwise encoding time reduction with radial acquisition (PETRA). MATERIALS AND METHODS: PETRA was obtained in 37 infants (gestational age: 23-43 weeks; postconceptional age: 34-46 weeks) using 3T magnetic resonance imaging (MRI) without respiratory gating. The visibility of the branching point and the airway structures, including the trachea and bronchi, on PETRA was scored by two experienced pediatric radiologists using a four-point scale (0-3). The rates of good visibility (score 3 or 2) were calculated for each airway structure. Interrater agreement was evaluated by intraclass correlation coefficient (ICC). RESULTS: For readers 1 and 2, good visibility was achieved for the branching point of the main bronchi (76% and 95%, respectively), trachea (97% and 95%, respectively), right main bronchus (92% and 92%, respectively), and left main bronchus (97% and 84%, respectively). Lower rates of visibility were achieved for the lobar bronchi. There was substantial agreement (ICC: 0.61-0.79) between the two readers for all the airway structures, except for the branching point at the right upper/middle lobe bronchi, for which there was moderate agreement (ICC: 0.56). CONCLUSION: PETRA has the potential for good airway visibility in infants, particularly for the trachea and main bronchi. LEVEL OF EVIDENCE: 3 J. Magn. Reson. Imaging 2017;45:839-844.

Optimized 4D time-of-flight MR angiography using saturation pulse.

PURPOSE: To assess arterial visibility on 4D time-of-flight (4D-TOF) by temporal magnetization transfer contrast pulse (t-MTC) and temporal tilted optimized nonsaturating excitation (t-TONE). 3D-TOF magnetic resonance angiography (MRA) is used for the noninvasive assessment of the intracranial arteries. However, it does not provide temporal information for diagnosing hemodynamics. To noninvasively obtain more detailed hemodynamics-related information, we developed a novel time-resolved MRA without the arterial spin labeling technique, termed 4D-TOF MRA using saturation pulse. MATERIALS AND METHODS: On a 3.0T MRI, three techniques were compared to optimize the visibility of the arteries above the circle of Willis; 1) simple 4D-TOF, 2) 4D-TOF with t-MTC, and 3) 4D-TOF with t-MTC and t-TONE. Eight healthy volunteers were scanned with these three sequences. The contrast changes between the background tissue and the arteries in temporal phases were assessed and compared quantitatively and qualitatively. RESULTS: The contrast between the background and the arteries for 4D-TOF with t-MTC and t-TONE was significantly higher than those for the other methods in delayed phases (P < 0.001).The qualitative assessment showed that 4D-TOF with t-MTC and with t-MTC and t-TONE provided better visualization of the intracranial artery than simple 4D-TOF (P < 0.001). CONCLUSION: 4D-TOF with t-TONE and t-MTC enabled observation of the intracranial hemodynamics. Optimized 4D-TOF provides high-quality images without image subtraction, and good visibility of the intracranial arteries even in the prolonged observation time. J. Magn. Reson. Imaging 2016;43:1320-1326.

Interhemispheric Lipoma, Callosal Anomaly, and Malformations of Cortical Development: A Case Series.

Intracranial lipomas are rare congenital malformations. The most common type of intracranial lipoma is the interhemispheric lipoma, which is frequently associated with callosal anomalies such as hypogenesis or agenesis of the corpus callosum. In contrast, interhemispheric lipomas are less often accompanied with malformations of cortical development (MCD). We report magnetic resonance imaging findings of three infants with an interhemispheric lipoma, associated with a callosal anomaly, and MCD: two infants with nodular interhemispheric lipoma, agenesis of the corpus callosum, and polymicrogyria, and one infant with interhemispheric curvilinear lipoma, hypoplasia of the corpus callosum, and heterotopias. An association was suggested regarding the occurrence of these malformations.

Improved image quality of helical computed tomography of the head in children by iterative reconstruction.

BACKGROUND AND PURPOSE: Iterative reconstruction (IR) offers noise reduction and improved image quality of computed tomography (CT). Our aim was to assess the imaging quality of non-contrast helical CT of the head in children using IR. MATERIALS AND METHODS: This study recruited 78 consecutive children aged ≤5 years (range: from 3 months to 5 years; mean: 1.7 years) who underwent an emergent non-enhanced helical CT of the head with no abnormal findings. The acquired data were reconstructed using filtered back projection (FBP) and sinogram-affirmed IR (SAFIRE) with strength levels of 2 (IR2) and 4 (IR4). The imaging quality of FBP, IR2 and IR4 was scored by two experienced neuroradiologists in terms of the contrast between the gray-white matter junction and artifacts from the skull at the level of the semioval center, basal ganglia and fourth ventricle. FBP, IR2 and IR4 scores were compared at each slice level. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for FBP, IR2 and IR4 and were compared among the three reconstruction algorithms. RESULTS: The score of IR2 and IR4 was significantly higher than that of FBP in terms of both the contrast between the gray-white matter junction and artifacts from the skull at each slice level (P<0.001). SNR and CNR on IR4 were the highest followed by those on IR2 and FBP (P<0.001). CONCLUSIONS: IR may improve the image quality of helical CT of the head in children.

Early magnetic resonance detection of cortical necrosis and acute network injury associated with neonatal and infantile cerebral infarction.

BACKGROUND: Knowledge of MRI findings in pediatric cerebral infarction is limited. OBJECTIVE: To determine whether cortical necrosis and network injury appear in the acute phase in post-stroke children and to identify anatomical location of acute network injury and the ages at which these phenomena are seen. MATERIALS AND METHODS: Images from 12 children (age range: 0-9 years; neonates [<1 month], n=5; infants [1 month-12 months], n=3; others [≥1 year], n=4) with acute middle cerebral artery (MCA) cortical infarction were retrospectively analyzed. Cortical necrosis was defined as hyperintense cortical lesions on T1-weighted imaging that lacked evidence of hemorrhage. Acute network injury was defined as hyperintense lesions on diffusion-weighted imaging that were not in the MCA territory and had fiber connections with the affected cerebral cortex. MRI was performed within the first week after disease onset. RESULTS: Cortical necrosis was only found in three neonates. Acute network injury was seen in the corticospinal tract (CST), thalamus and corpus callosum. Acute network injury along the CST was found in five neonates and one 7-month-old infant. Acute network injury was evident in the thalamus of four neonates and two infants (ages 4 and 7 months) and in the corpus callosum of five neonates and two infants (ages 4 and 7 months). The entire thalamus was involved in three children when infarction of MCA was complete. CONCLUSION: In acute MCA cortical infarction, MRI findings indicating cortical necrosis or acute network injury was frequently found in neonates and early infants. Response to injury in a developing brain may be faster than that in a mature one.

Turbo spin-echo-based enhanced acceleration-selective arterial spin labeling without electrocardiography or peripheral pulse unit triggering and contrast enhancement for lower extremity MRA.

PURPOSE: Lower extremity magnetic resonance angiography (MRA) without electrocardiography (ECG) or peripheral pulse unit (PPU) triggering and contrast enhancement is beneficial for diagnosing peripheral arterial disease (PAD) while avoiding synchronization failure and nephrogenic systemic fibrosis. This study aimed to compare the diagnostic performance of turbo spin-echo-based enhanced acceleration-selective arterial spin labeling (eAccASL) (TSE-Acc) of the lower extremities with that of turbo field-echo-based eAccASL (TFE-Acc) and triggered angiography non-contrast enhanced (TRANCE). METHODS: Nine healthy volunteers and a patient with PAD were examined on a 3.0 Tesla magnetic resonance imaging (MRI) system. The artery-to-muscle signal intensity ratio (SIR) and contrast-to-noise ratio (CNR) were calculated. The arterial visibility (1: poor, 4: excellent) and artifact contamination (1: severe, 4: no) were independently assessed by two radiologists. Phase-contrast MRI and digital subtraction angiography were referenced in a patient with PAD. Friedman's test and a post-hoc test according to the Bonferroni-adjusted Wilcoxon signed-rank test were used for the SIR, CNR, and visual assessment. p < 0.05 was considered statistically significant. RESULTS: No significant differences in nearly all the SIRs were observed among the three MRA methods. Higher CNRs were observed with TSE-Acc than those with TFE-Acc (anterior tibial artery, p = 0.014; peroneal artery, p = 0.029; and posterior tibial artery, p = 0.014) in distal arterial segments; however, no significant differences were observed upon comparison with TRANCE (all p > 0.05). The arterial visibility scores exhibited similar trends as the CNRs. The artifact contamination scores with TSE-Acc were significantly lower (but within an acceptable level) compared to those with TFE-Acc. In the patient with PAD, the sluggish peripheral arteries were better visualized using TSE-Acc than those using TFE-Acc, and the collateral and stenosis arteries were better visualized using TSE-Acc than those using TRANCE. CONCLUSION: Peripheral arterial visualization was better with TSE-Acc than that with TFE-Acc in lower extremity MRA without ECG or PPU triggering and contrast enhancement, which was comparable with TRANCE as the reference standard. Furthermore, TSE-Acc may propose satisfactory diagnostic performance for diagnosing PAD in patients with arrhythmia and chronic kidney disease.

Utility of Echo-planar Imaging with Compressed Sensitivity Encoding (EPICS) in the Evaluation of Small Breast Cancers Using Diffusion-weighted Imaging with Background Suppression (DWIBS).

PURPOSE: High b-value acquisition and diffusion-weighted imaging with background suppression (DWIBS) are desirable in high-specificity breast cancer diagnosis on non-contrast-enhanced magnetic resonance imaging; however, this inherently results in a lower signal-to-noise ratio (SNR). Compressed sensitivity encoding (C-SENSE), which combines SENSE with compressed sensing, improves the SNR by reducing noise. Recent technological improvements allow us to incorporate this acceleration technique into echo-planar imaging, called echo-planar imaging with C-SENSE (EPICS). This study aimed to compare image quality and reliability of the apparent diffusion coefficient (ADC) between DWIBS obtained using SENSE and EPICS in patients with small breast cancers. METHODS: Thirty-seven patients with pathologically confirmed breast cancer underwent DWIBS, and images were reconstructed using both conventional SENSE (SENSE-DWIBS) and EPICS (EPICS-DWIBS). Two board-certified radiologists independently evaluated lesion conspicuity (LC) and noise using a 5-point grading scale. The same 2 radiologists independently measured SNR, contrast-to-noise ratio (CNR), and the mean cancer ADC. The Pearson coefficient and Bland-Altman plot were applied to assess the accuracy of ADCs. RESULTS: LC scores were higher with EPICS than with SENSE, reaching significance for one reviewer but not the other reviewer. Noise ratings on visual evaluation were significantly lower with EPICS than with SENSE (P < 0.001 for both reviewers). SNR was significantly higher with EPICS than with SENSE (P < 0.005 for both reviewers). CNR was significantly higher with EPICS than with SENSE (P < 0.001 for both reviewers). Bland-Altman plots of cancer ADCs using EPICS-DWIBS and SENSE-DWIBS showed excellent concordance, with a bias of 0.026 × 10-3 mm2/s and limits of agreement ranging 0.054 × 10-3 mm2/s; the Pearson's correlation coefficient was 0.997 (P < 0.0001). CONCLUSION: EPICS enhances breast DWIBS image quality, with improved SNR and CNR and reduced noise levels. The ADCs of breast cancers obtained using EPICS were almost perfectly correlated with those obtained using conventional SENSE.

Syndromes associated with vascular tumors and malformations: a pictorial review.

Use of the International Society for the Study of Vascular Anomalies (ISSVA) classification system has been strongly recommended in recent years because of the need for separate therapeutic measures for patients with vascular tumors and malformations. In the ISSVA classification system, vascular tumors, which are neoplastic, are distinguished from vascular malformations, which are caused by vascular structural anomalies and are not neoplastic, on the basis of the presence or absence of neoplastic proliferation of vascular endothelial cells. It is important that radiologists be familiar with the development, diagnosis, and treatment of vascular tumors and malformations, especially the imaging features of low- and high-flow vascular malformations. Some vascular tumors and malformations develop in isolation, whereas others develop within the phenotype of a syndrome. Syndromes that are associated with vascular tumors include PHACE syndrome. Syndromes that are associated with vascular malformations include Sturge-Weber, Klippel-Trénaunay, Proteus, blue rubber bleb nevus, Maffucci, and Gorham-Stout syndromes, all of which demonstrate low flow, and Rendu-Osler-Weber, Cobb, Wyburn-Mason, and Parkes Weber syndromes, all of which demonstrate high flow. Because imaging findings may help identify such syndromes as systemic, it is important that radiologists familiarize themselves with these conditions.

[Visualization of Cerebrospinal Fluid Dynamics by Respiratory Motion Using Phase Dispersion: Optimization of Spatial and Temporal Resolutions].

PURPOSE: The purpose of this study was to investigate the optimal spatial resolution and temporal resolution of dynamic improved motion-sensitized driven-equilibrium steady-state free precession for visualization of respiratory-driven cerebrospinal fluid (CSF) dynamics. METHODS: We investigated the differences in the visualization using the midsagittal cross-sections of nine healthy volunteers by three imaging conditions. (A: spatial resolution 0.49×0.49×5 mm, temporal resolution 1000 ms; B: 0.49×0.49×5 mm, 430 ms; and C: 0.78×0.78×5 mm, 200 ms). First, we calculated the CSF of the third and fourth ventricles and the signal-to-noise ratio (SNR) of the pons. Next, we calculated the signal intensity ratio (SIR) of the CSF flowing at 10 cm/s or more and the CSF flowing at 10 cm/s or less due to respiration. We also calculated the difference between the inspiration and expiration SIR. Furthermore, 1) the presence of flow in the third and fourth ventricles centered on the cerebral aqueduct and 2) the change in flow due to respiration was investigated by a three-point scale visual assessment by seven radiological technologists. RESULTS: The SNR was the highest in A, the next highest in B, and the lowest in C in all cases. There were significant differences between A and B, and A and C in CSF of the third and fourth ventricles. However, there was no significant difference between B and C. The CSF signal intensity changed with respiration. The SIR of the third ventricle was higher on inspiration and lower on expiration. Conversely, the SIR of the fourth ventricle was lower on inspiration and higher on expiration. There was a significant difference between A and C and B and C in each SIR (p<0.05). The difference between inspiration and expiration SIR was the highest in B, the next highest in A, and the lowest in C in both the third and fourth ventricles. Significant differences were found between A and C, and between B and C (p<0.05). There was no significant difference in the presence of flow in the third and fourth ventricles centered on the cerebral aqueduct (p=0.264). On the other hand, there was a significant difference between the imaging conditions in the change in flow due to respiration, with B having a higher value than the others (p<0.001). CONCLUSION: The optimal spatial and temporal resolutions were 0.49×0.49×5 mm and 430 ms, respectively. The results also suggest that it is important to carefully set the imaging conditions for the spatial and temporal resolutions because of the use of phase dispersion in this method.

Temperature measurement of intracranial cerebrospinal fluid using diffusion tensor imaging after revascularization surgery in Moyamoya disease.

OBJECTIVE: Brain temperature monitoring using a catheter thermometer has been reported to be a useful technique to predict prognosis in neurosurgery. To investigate the possibility of measuring intracranial cerebrospinal fluid temperature for postoperative monitoring in patients with Moyamoya disease (MMD) after bypass surgery. MATERIALS AND METHODS: This study evaluated fifteen patients with MMD who were indicated for bypass surgery. Diffusion tensor imaging for brain thermometry were performed on a 1.5-T MR scanner. Intracranial cerebrospinal fluid temperature with/without considering the fractional anisotropy component, body temperature, C-reactive protein levels, white blood cell count, and cerebral blood flow measured by 123I-IMP single-photon emission computed tomography were obtained before surgery and 1-3 days after surgery. Pixel values considered to be signal outliers in fractional anisotropy processing were defined as cerebrospinal fluid noise index and calculated. Wilcoxon signed-rank test and effect size were performed to compare the changes before and after revascularization. Spearman's rho correlation coefficient was used to analyze the correlations between each parameter. Statistical significance was defined as p < 0.05. RESULTS: All parameter values became significantly higher compared to those measured before revascularization (p < 0.01 in all cases). The effect sizes were largest for the cerebrospinal fluid temperature with fractional anisotropy processing and for C-reactive protein levels (Rank-biserial correlation = 1.0). The cerebrospinal fluid noise index and cerebrospinal fluid temperatures with fractional anisotropy processing (r = 0.84, p < 0.0001) or without fractional anisotropy processing (r = 0.95, p < 0.0001) showed highly significant positive correlations. Although no significant correlation was observed, cerebrospinal fluid temperatures with fractional anisotropy had small or moderately positive correlations with cerebral blood flow, body temperature, C-reactive protein levels, and white blood cell count (r = 0.37, 0.42, 0.41, and 0.44, respectively; p > 0.05). CONCLUSION: Our findings suggest the possibility of postoperative monitoring for MMD patients by measuring intracranial cerebrospinal fluid temperature with fractional anisotropy processing. Intracranial cerebrospinal fluid temperature might be considered as combined response since cerebrospinal fluid, body temperature, and inflammation are equally correlated.

Simultaneous Visualization of the Thoracic Duct and Blood Vessels Using MRI: A Comparison Between Balanced Turbo-field-echo and Spin-echo.

OBJECTIVE: Magnetic resonance thoracic ductography (MRTD), concomitant with blood vessel imaging, provides useful anatomical information. The purpose of this study was to assess the visibility of the thoracic duct and blood vessels simultaneously by MRTD using balanced turbo-field-echo (bTFE) and turbo spin-echo (TSE). METHODS: MRTDs concomitant with blood vessel imaging on bTFE and TSE were obtained for 10 healthy volunteers with a 1.5T-magnetic resonance unit. Visibility of the thoracic duct, blood vessels in the thoracic region; motion artifacts; and overall image quality were scored by two radiologists using three-to-five-point scales; those were compared between bTFE and TSE. RESULTS: The thoracic duct was generally well-visualized on MRTD sequences. The upper part of the thoracic duct was better visualized on TSE than on bTFE (p < 0.05). The blood vessels were well visualized on bTFE and TSE; the bilateral subclavian arteries and the right subclavian veins were better visualized on TSE than on bTFE (all p < 0.05). Motion artifacts and overall image quality were better on TSE than on bTFE (p = 0.0039 and 0.0020, respectively). CONCLUSION: MRTD concomitant with blood vessel imaging on TSE has better visibility of the thoracic duct and blood vessels than bTFE.

Computed diffusion-weighted imaging with a low-apparent diffusion coefficient-pixel cut-off technique for breast cancer detection.

OBJECTIVE: This study aimed to compare the image quality and diagnostic performance of computed diffusion-weighted imaging (DWI) with low-apparent diffusion coefficient (ADC)-pixel cut-off technique (cDWI cut-off) and actual measured DWI (mDWI). METHODS: Eighty-seven consecutive patients with malignant breast lesions and 72 with negative breast lesions who underwent breast MRI were retrospectively evaluated. Computed DWI with high b-values of 800, 1200, and 1500 s/mm2 and ADC cut-off thresholds of none, 0, 0.3, and 0.6 (×10-3 mm2/s) were generated from DWI with two b-values (0 and 800 s/mm2). To identify the optimal conditions, two radiologists evaluated the fat suppression and lesion reduction failure using a cut-off technique. The contrast between breast cancer and glandular tissue was evaluated using region of interest analysis. Three other board-certified radiologists independently assessed the optimised cDWI cut-off and mDWI data sets. Diagnostic performance was evaluated using receiver operating characteristic (ROC) analysis. RESULTS: When an ADC cut-off threshold of 0.3 or 0.6 (× 10-3 mm2/s) was applied, fat suppression improved significantly (p < .05). The contrast of the cDWI cut-off with a b-value of 1200 or 1500 s/mm2 was better than the mDWI (p < .01). The ROC area under the curve for breast cancer detection was 0.837 for the mDWI and 0.909 for the cDWI cut-off (p < .01). CONCLUSION: The cDWI cut-off provided better diagnostic performance than mDWI for breast cancer detection. ADVANCES IN KNOWLEDGE: Using the low-ADC-pixel cut-off technique, computed DWI can improve diagnostic performance by increasing contrast and eliminating un-suppressed fat signals.