Radiology

Influence of virtual monochromatic spectral image at different energy levels on motion artifact correction in dual-energy spectral coronary CT angiography Abstract Purpose To investigate the influence of virtual monochromatic spectral (VMS) CT images at different energy levels on the effectiveness of a motion correction technique (SSF) in dual-energy Spectral coronary CT angiography (CCTA). Materials and methods 29 cases suspected of or diagnosed with coronary artery disease underwent Spectral CCTA using a prospective ECG triggering with 250 ms padding time. SSF was applied to the determined least-motion phase to generate 6 additional sets of VMS images with energy levels from 40 to 100 keV. CT value and standard deviation (SD) in the aortic root and epicardial adipose tissue were measured. Image quality of the RCA, LAD and LCX was evaluated on a per-vessel basis in each patient. Two reviewers evaluated the artery using the score of the segment. Results The low energy VMS images increased CT value and image noise compared with higher-energy VMS images, except 90 keV and 100 keV. The CNR of 40–70 keV were higher than those of 80–100 keV (P < 0.05). The image quality scores for images at 50–80 keV were higher than those of 40, 90, and 100 keV (P < 0.05), and the VMS image quality at 50 keV and 60 keV with SSF was the highest. Conclusion SSF can effectively reduce the motion artifacts when coronary vessels have suitable contrast enhancement which can be achieved by adjusting energy levels of VMS images.

Safety margin of radiofrequency ablation for hepatocellular carcinoma: a prospective study using magnetic resonance imaging with superparamagnetic iron oxide Abstract Purpose In radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC), it is difficult to assess the ablative margin (AM) precisely by comparing pre- and post-RFA CT images. We prospectively studied the AMs using magnetic resonance imaging (MRI) with pre-administered superparamagnetic iron oxide (SPIO). SPIO is safe for kidney disease patients. Materials and methods Hepatocellular carcinoma patients were treated with RFA within 8 h of SPIO administration. On T2*-weighted MRI performed 4–7 days later, AM was visualized as a hypointense rim. The ablation status was classified as AM(+) if the rim completely surrounded the tumor, AM(0) if the rim was partly discontinuous without tumor protrusion, and AM(−) if the rim was partly discontinuous with tumor protrusion. The minimal thickness of AM was measured. AM(−) tumors were re-treated consecutively. Results In total, 85 HCCs ablated in 76 patients were evaluated. The local recurrence rate at 3 years was 2% for AM(+) tumors and 34% for AM(0) tumors (p < 0.01). In addition, no local recurrence was seen in the tumors with an AM of ≥ 2 mm. Conclusion MRI with pre-administered SPIO is useful for determining the AM precisely, and an AM of ≥ 2 mm is recommended for curative RFA. Trial registration number This study was registered with UMIN Clinical Trials Registry (UMIN 000025406).

The usefulness of full-iterative reconstruction algorithm for the visualization of cystic artery on CT angiography Abstract Purpose To evaluate the potential of full-iterative reconstruction (IR) for improving image quality of the cystic artery on CT angiography and to assess observer performance. Methods Thirty patients who underwent both liver dynamic CT and conventional angiography were included in this retrospective study. All CT data were reconstructed through filtered back projection (FBP), adaptive iterative dose reduction 3D (AIDR3D), and forward-projected, model-based, iterative reconstruction solution (FIRST), respectively. In objective study, we analyzed mean ΔCT numbers (the difference between the HU peak of the vessel and the background) and full-width at tenth-maximum (FWTM) of three parts of the cystic artery by profile curve method comparing the three reconstructions. Subjectively, visualization was evaluated using a four-point scale performed by two blinded observers. ANOVA was used for statistical analysis. Results In all parts of the cystic artery, the mean ΔCT number of FIRST was shown to be significantly better than that of FBP and AIDR3D (p < 0.05). FWTM in FIRST was the smallest in all of the vessels. The mean visualization score was significantly better with FIRST than with other CT reconstructions (p < 0.05). Conclusions The FIRST algorithm led to improved CTA visualization of the cystic artery.

Postmortem volume change of the spleen and kidney on early postmortem computed tomography: comparison with antemortem computed tomography Abstract Purpose To clarify an early postmortem change, we investigated the volume changes of the spleen and kidney on postmortem CT compared with antemortem CT in the same patients. Materials and methods We retrospectively evaluated the volumes of 56 spleens (56 cases) and 50 kidneys (25 cases) using antemortem and postmortem CT, which were performed within 168 min after death. We divided the cases of spleen analysis into a hemorrhagic group (n = 12) and a non-hemorrhagic group (n = 44). Results The volumes of the organs before and after death were 101.0 ± 70.9 (cm3, mean ± standard deviation) and 81.1 ± 57.8 in spleens, 120.3 ± 49.2 and 109.2 ± 39.2 in kidneys, respectively. Both spleens and kidneys shrank after death (p < 0.05). The volumes of spleens before and after death were 111 ± 66.5 and 67.5 ± 27.7 in the hemorrhagic group, and 98.2 ± 72.5 and 84.9 ± 63.3 in the non-hemorrhagic group, respectively. The median value of the ratio of postmortem splenic volume to antemortem volume in the hemorrhagic group (65.0%) was smaller than the one in the non-hemorrhagic group (90.5%) (p < 0.05). Conclusion We demonstrated that spleens and kidneys significantly reduced in size after death. The rate of shrinkage of spleens in the hemorrhagic group significantly became larger than the one in the non-hemorrhagic group.

CT findings in diagnosis of gastric bare area invasion: potential prognostic factors for proximal gastric carcinoma Abstract Purpose To investigate the correlation between the preoperative CT findings in diagnosis of gastric bare area (GBA) invasion and the 3-year-overall survival (OS) of patients with proximal gastric carcinoma (PGC). Methods 108 consecutive patients with PGC confirmed by biopsy underwent MDCT scan prior to gastrectomy were enrolled retrospectively from Dec 2009 to Dec 2014. GBA invasion in PGC were evaluated by measuring the direct CT signs including transmural involvement and lymph nodes in the GBA. The indirect signs were also evaluated including the infiltration of the diaphragm, gastrophrenic ligament and perigastric fat. Kaplan–Meier estimates with log-rank test and Cox proportional hazard model were used for analysis. Results The two raters achieved excellent agreement. Univariate Kaplan–Meier estimates indicated that postoperative chemotherapy (p = 0.003), transmural involvement (p < 0.001), lymph nodes in the GBA (p = 0.015) and cT staging (p = 0.002) were associated with OS. Cox proportional hazard model indicated that the transmural involvement (HR = 8.194, 95% CI 2.15–31.266), diaphragm involvement (HR = 0.21, 95% CI 0.042–0.986), perigastric fat infiltration (HR = 0.125, 95% CI 0.018–0.885; HR = 0.02, 95% CI 0.001–0.264), and cT staging were independent prognostic factors for OS. Conclusion CT findings of GBA invasion in patients with PGC, not only the transmural involvement but also the indirect signs are independent prognostic factors potentially, which should be given more emphasis in future clinical practice.

Intra-aneurysmal air after flow diversion treatment in intracranial aneurysms: incidence, characteristics and clinical significance Abstract Objective To describe the rate and characteristics of air bubble retention (ABR) within cerebral aneurysms treated by flow diversion. Methods Procedural flat detector CT (FDCT) studies were scrutinized for the presence of air bubbles (density < − 200 HU) in patients treated by flow diversion. Patients with intrasaccular treatment or previous clipping were excluded. Clinical outcomes, procedural angiograms, aneurysm characteristics and imaging features of air within the aneurysm were evaluated. Results Bubbles were noted in 17.1% of 105 aneurysms in 85 FDCTs. Aneurysms with ABR were significantly larger (mean diameter: 18.9 versus 7.5 mm, P < 0.0001). There was a trend for the use of multiple devices during the treatment of these aneurysms (72.2% vs 49.4%, P = 0.071). All of the bubbles were located rostrally in the aneurysm sac and were smaller than 6 mm (mean diameter: 2.1 ± 1.3 mm). None of the patients had post-procedural neurological deterioration. The air had spontaneously disappeared on follow-up CT images (available in 12 patients) obtained at a mean follow-up duration of 48 h. Conclusions ABR is not infrequent in cerebral flow diversion procedures. It is a clinically silent and self-limited technical complication. We propose air entrapment or filtration through the flow diverter as causative factors.

MR enterography: what is next after Crohn's disease? Abstract Within the gastrointestinal system, the small bowel represents the most difficult site to approach with imaging modalities. During the last decades, magnetic resonance enterography has reached an increasing interest, up to be considered an essential part in the diagnostic framework of Crohn's disease patients. Nevertheless, the distention of the intestinal loops provided by the administration of oral contrast medium, the possibility of a dynamic evaluation, and the lack of radiation exposure are huge advantages that can be exploited for the assessment of other clinical conditions affecting the small bowel. Physicians and radiologists should be aware of the possibilities offered by this technique, looking at it as a trustful alternative to the well-worn radiological examinations. In this respect, the purpose of this work is to show some uncommon clinical conditions that can be assessed with magnetic resonance enterography and that fall within the various differential diagnosis of the intestinal disorders.

Risk factors for local recurrence of hepatocellular carcinoma after transcatheter arterial chemoembolization with drug-eluting beads (DEB-TACE) Abstract Purpose To identify the risk factors for local recurrence in hepatocellular carcinoma (HCC) patients treated with transcatheter arterial chemoembolization (TACE) with drug-eluting beads (DEB-TACE). Materials and methods In this retrospective study, 35 patients (27 males, 8 females; median age 73 years) with 116 tumors (median size 14 mm) treated with DEB-TACE from May 2014 to September 2018 were evaluated. Age, sex, etiology, Child–Pugh class, alpha-fetoprotein, des-gamma-carboxyprothrombin, previous conventional TACE, tumor location, tumor size, tumor number, contact with the liver surface, level of embolization, corona enhancement on CT during hepatic arteriography, vascular lakes, additional embolization with gelatin sponge particles, and supplying vessels on digital subtraction angiography (DSA) after embolization were analyzed. Results Univariate analysis showed that advanced age, female, large tumor, contact with the liver surface, and residual supplying vessels were significant risk factors for local recurrence (p = 0.012, 0.0013, 0.0023, 0.025, and < 0.001, respectively). On multivariate logistic analysis, large tumor, contact with the liver surface, and residual supplying vessels on DSA were significant risk factors for local recurrence (p = 0.0026, 0.038, and < 0.001, respectively). Conclusion Large tumor size, contact with the liver surface, and residual supplying vessels on DSA were significant risk factors associated with local recurrence after DEB-TACE for HCC.

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.

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.

Alexandros Sfakianakis
Anapafseos 5 . Agios Nikolaos
Crete.Greece.72100
2841026182

6948891480

alsfakia@gmail.com