Japanese Journal of Radiology

CT gastrography “wall-carving technique” of gastric cancer: impact of contrast enhancement based on layer depth Abstract Purpose Wall-carving technique (WC) is a special volume rendering technique of three-dimensional CT gastrography that can illustrate the enhancement of gastric wall at an arbitrary depth. We conducted the present study to evaluate the impact of contrast enhancement based on layer depth on WC of gastric cancer and to correlate them with pathological findings. Methods The subjects of this retrospective study consisted of 36 patients with advanced gastric cancer (22 men, 14 women; age range, 39–90 years; median, 67 years) who underwent contrast-enhanced CT before surgery. WC images of arterial phase were divided into first and second layer. Two radiologists in consensus evaluated the contrast enhancement of WC images for each layer and correlated with pathologic factors. Results Twenty-six (72%) of the gastric cancers showed a well-enhanced lesion in the first layer at the arterial phase on WC images, and 18 (50%) showed a well-enhanced lesion in the second layer. The study of second layers showed that the well-enhanced group had significantly more cases of differentiated type histology and intermediate stroma than the normally to poorly enhanced group (p = 0.008 and 0.0026). Conclusion The contrast enhancement on WC of gastric cancer showed a significant relationship with pathological factors based on layer depth.

Comparison of magnetization transfer contrast of conventional and simultaneous multislice turbo spin echo acquisitions focusing on excitation time interval Abstract Purpose Image contrast differs between conventional multislice turbo spin echo (conventional TSE) and multiband turbo spin echo (SMS-TSE). Difference in time interval between excitations for adjacent slices (SETI) might cause this difference. This study aimed to evaluate the influence of SETI on MT effect for conventional TSE and compare conventional TSE with SMS-TSE in this respect. Materials and methods Three different agar concentration phantoms were scanned with conventional TSE by adjusting SETI and TR. Signal change for different SETI was evaluated using Pearson’s correlation analysis. SMS-TSE was acquired by changing TR similarly. Three human volunteers were scanned with similar settings to evaluate reproducibility of the phantom results in human brain. Results In conventional TSE, shorter SETI induced larger signal reduction. Longer TR and higher agar concentration emphasized this characteristic. Significant linear correlation (P < 0.05) was found in the major cases. The SMS-TSE signal intensity in each TR and phantom was smaller than the assumable levels in conventional TSE when the slices were simultaneously excited. Similar characteristic was observed in human brain. Conclusion Shorter SETI results in larger MT effect in conventional TSE. The contrast change in SMS-TSE was larger than the supposable level from simultaneous excitation, which needs consideration in clinics.

Improvement of the MRI and clinical features of Asian Graves’ ophthalmopathy by radiation therapy with steroids Abstract Purpose To evaluate the effectiveness of radiation therapy and steroids for Asian patients with Graves’ ophthalmopathy using the clinical activity score (CAS), and changes in external ocular muscles and eye proptosis determined by magnetic resonance imaging (MRI). Materials and methods We retrospectively reviewed 48 patients who received combined orbital radiation and systemic glucocorticoids in our hospital. MRI was performed both before and 1 month after treatment in all patients. We calculated the areas of five extraocular muscles and the degree of proptosis on transverse sections, and we evaluated the activity of the disease using CAS before and 1 month after treatment and toxicity. Results The areas of external ocular muscles, the length of eye prominence and CAS were significantly improved by the combination of orbital radiation and steroids. The change in the area of the medial rectus muscle had a significant correlation with the change in CAS (P < 0.05). Graves’ ophthalmopathy progressed again in 4 of the 48 patients; however, there were no patients with serious side effects in a median observation period of 41.5 months. Conclusion Treatment with the combination of orbital radiation and systemic glucocorticoids is subjectively and objectively effective for Asian Graves’ ophthalmopathy without severe toxicity.

Cinematic rendering: a new imaging approach for ulcerative colitis Abstract Purpose Cinematic rendering (CR) is a new technique for visualizing volumetric three-dimensional data. The purpose of this study was to investigate the added value of CR to conventional computed tomography (CT) in the diagnosis and evaluation of ulcerative colitis (UC). Materials and methods We retrospectively evaluated the CT data of 48 patients (33 men, 15 women; mean age, 44.35 years) with a definitive diagnosis of UC. All patients underwent conventional CT and CR, and had colonoscopy results. Two radiologists independently reviewed the conventional CT images first without and then with CR. Then, the imaging value of CR was evaluated by both radiologists together. The readers were blinded to the disease extent. The diagnostic performance of CR for both readers was assessed by receiver-operating characteristic (ROC) curve analysis. Results There were 23 cases of mild to moderate UC and 25 cases of severe UC, which were divided into two groups. Both readers showed improved diagnostic performance with the addition of CR (the area under the ROC curve improved from 0.676 to 0.804, P = 0.0255, and from 0.679 to 0.826, P = 0.0049, for readers 1 and 2, respectively). Full view of the lesion and contrast enhancement was not significantly different between the two groups (P > 0.05). Increased mesenteric vascularity and the comb sign on CR were more clearly observed in the severe group (P < 0.05). Conclusion Adding CR to conventional CT improved the diagnostic performance of evaluating the extent of UC.

Displacement of the transverse colon is a highly specific computed tomography finding for the preoperative diagnosis of a transomental hernia Abstract Purpose A transomental hernia (TOH) is a rare type of internal hernia and is associated with a high strangulation rate and high mortality rate. Displacement of the transverse colon on computed tomography (CT) may be specific to a TOH and may facilitate an early diagnosis. The aim of this study was to verify the effectiveness of a novel approach assessing displacement of the transverse colon for the preoperative diagnosis of a TOH. Materials and methods We retrospectively reviewed the CT and operative data of 113 patients who underwent surgery for small bowel obstruction (SBO) between 2011 and 2018. The proportion of transverse colon loops posterior to dilated intestinal loops (PTPI) was calculated. Results The patients were divided into a TOH group (n = 7) and other SBO group (n = 106). The median PTPI was significantly higher in the TOH group than in the other SBO group (67% [0–97%] vs. 0% [0–100%], Wilcoxon’s test, p = 0.03). A receiver operating characteristic curve showed that when the PTPI was ≥ 57%, its sensitivity and specificity for a TOH were 71% and 94%, respectively. Conclusion The PTPI is a reliable quantitative measure to distinguish a TOH from other types of SBOs.

Single-isocenter volumetric-modulated Dynamic WaveArc therapy for two brain metastases Abstract Purpose A new irradiation technique, volumetric-modulated Dynamic WaveArc therapy (VMDWAT), based on sequential non-coplanar trajectories, can be performed using the Vero4DRT. This planning study compared the dose distribution and treatment time between single-isocenter volumetric-modulated arc therapy (VMAT) with multiple straight non-coplanar arcs and single-isocenter VMDWAT in patients with two brain metastases. Materials and methods Twenty patients with two planning target volumes exceeding 2.0 cm3 were included. Both VMAT and VMDWAT plans were created with single isocenter and a prescribed dose of 28 Gy delivered in five fractions. Target conformity was evaluated using indices modified from the RTOG-CI (mRTOG-CI) and IP-CI (mIP-CI). Results VMDWAT significantly improved both mRTOG-CI and mIP-CI and reduced the volume of normal brain tissue receiving 25 and 28 Gy compared to VMAT. The two modalities did not significantly differ in terms of the volume of normal brain tissue receiving 5, 10, 12, 15, and 20 Gy. The mean treatment time was significantly shorter in the VMDWAT group. Conclusion VMDWAT significantly improved dose distribution in a shorter treatment time compared to VMAT in patients treated for two brain metastases. Single-isocenter VMDWAT may thus be a promising treatment for two brain metastases.

Carotid-vertebrobasilar anastomosis: magnetic resonance and computed tomographic angiographic demonstration Abstract Carotid-vertebrobasilar (VB) anastomoses are rare and usually found incidentally, but they can have clinical significance. Their variance can represent aneurysm formation at the origin of the anomalous artery, cerebral ischemia due to unique blood flow, or other complications. Thus, recognition and correct diagnosis of these anomalous vessels are important when interpreting magnetic resonance (MR) and computed tomography (CT) angiography. This pictorial essay presents MR and CT angiographic images of several types of persistent fetal carotid-VB anastomoses, including those involving the proatlantal, hypoglossal, and trigeminal arteries as well as their variants. Images depict types 1 and 2 proatlantal arteries, persistent second cervical intersegmental artery, persistent hypoglossal artery (PHA), PHA of external carotid origin, two types of the PHA variant, posterior inferior cerebellar artery arising from the jugular branch of the ascending pharyngeal artery, lateral and medial types of persistent trigeminal arteries (PTAs), and four types of PTA variants.

The opacity of mineral ion-loaded bead (DC beads ® ) on low-keV monochromatic images from dual energy CT and T1-weighted gradient-echo MRI Abstract Purpose To evaluate the opacity of DC beads® (DCB) loaded with mineral ions on low-keV monochromatic images from dual energy computed tomography (DECT) and T1-weighted gradient-echo (T1-GRE) MRI. Materials and methods Fe2+ or Ca2+-loaded DCBs were prepared by mixing DCBs in 100 mM FeSO4 or CaSO4 solution and scanned by DECT from 10 min to 27 h after mixing. The Hounsfield units (HUs) of sedimented DCBs on 40-keV monochromatic images were measured. Next, we mixed DCBs in 100, 10, 5 and 1 mM FeSO4 solutions, and scanned these solutions from 15 to 120 min after mixing using a 3 T MR scanner. The signal–noise ratios (SNRs) of sedimented DCBs on T1-GRE were measured. Venous blood was scanned to compare with DCBs. Results The CT values of DCBs in FeSO4 and CaCl2 solutions gradually increased, and were 113.3 and 43.1 HU at 27 h, respectively; that of blood was 17.8 HU. The SNR of DCB in 1 mM FeSO4 solution increased and achieved equilibrium at 120 min, and was 120.5 and higher than in the other FeSO4 solutions. The SNR of blood was 49.7. Conclusion Optimally Fe2+-loaded DCBs can be discriminated from venous blood on 40-keV monochromatic images from DECT and T1-GRE.

Liver imaging reporting and data system (LI-RADS) v2018: comparison between computed tomography and gadoxetic acid-enhanced magnetic resonance imaging Abstract Purpose To determine the consistency of major hepatocellular carcinoma (HCC) features between CT and MRI based on Liver Imaging Reporting and Data System (LI-RADS) v2018 and to investigate the additional value on gadoxetic acid-enhanced MRI. Materials and methods Patients who underwent dynamic CT and gadoxetic acid-enhanced MRI within 1 month were investigated. Two radiologists evaluated the presence of major HCC features and categorized observations using LI-RADS v2018 algorithm. In addition, each observation was recorded as hyper-, iso-, or hypo-intensity on hepatobiliary-phase (HBP) images. Results Sixty-one patients with 110 observations were identified. Among 88 observations classified as LR-3, 4 or 5, arterial phase hyper-enhancement and washout appearance showed higher frequencies on CT than on MRI (75.0% vs. 58.0%, P < 0.001, and 60.2% vs. 44.3%, P = 0.014, respectively). Of the 59 LR-3 observations categorized on MRI, 70.0% of observations with hypo-intensity on HBP images were HCCs, whereas 89.5% of observations with iso- or hyper-intensity on HBP images were non-HCCs (P < 0.001) Conclusion The frequencies of arterial phase hyper-enhancement and washout appearances were higher on CT than on gadoxetic acid-enhanced MRI. For LR-3 observations, adding the hepatobiliary-phase hypo-intensity to major features improved the diagnostic performance of MRI in distinguishing HCCs from non-HCC lesions.

Effect of renal denervation procedure on left ventricular mass, myocardial strain and diastolic function by CMR on a 12-month follow-up Abstract Purpose To investigate the effects of renal denervation (RDN) on left ventricular (LV) mass, myocardial strain and diastolic function in patients with treatment-resistant arterial hypertension by cardiac magnet resonance imaging on a 12-month follow-up. Materials and methods Sixteen patients (38% female) were examined before and 12 months after RDN. LV morphology and strain were analyzed. Diastolic function was determined by early (EPFR) and atrial peak filling rates (APFR) derived from differential volume–time-curve analysis. Clinical visits included 24-h ambulant blood pressure monitoring (ABPM). Results Twelve months after RDN LV mass decreased from 80 ± 21 g/m2 to 74 ± 20 g/m2 (P < 0.05). Global radial (35 ± 12% vs. 41 ± 10%, P < 0.05) and longitudinal strain improved (− 15 ± 4% vs. − 17 ± 3%, P < 0.05). Global circumferential strain (− 16 ± 5% vs. − 18 ± 4%, P = 0.12) remained unchanged. The parameter of diastolic LV function PFRR (EPFR/APFR) improved following RDN (0.9 ± 0.4 vs. 1.1 ± 0.5, P < 0.05). Individual changes of LV mass were associated with an increase of EPFR (r = − 0.54, P < 0.05) and a reduction of APFR by trend (r = 0.45, P = 0.08). Systolic ABPM showed a decrease by trend (152 mmHg vs. 148 mmHg, P = 0.08). Conclusions After RDN we observed a reduction of LV mass, improvement of global strain and diastolic function.