Variation in Hounsfield unit calculated using dual-energy computed tomography: comparison of dual-layer, dual-source, and fast kilovoltage switching technique.

The purpose of the study is to investigate the variation in Hounsfield unit (HU) values calculated using dual-energy computed tomography (DECT) scanners. A tissue characterization phantom inserting 16 reference materials were scanned three times using DECT scanners [dual-layer CT (DLCT), dual-source CT (DSCT), and fast kilovoltage switching CT (FKSCT)] changing scanning conditions. The single-energy CT images (120 or 140 kVp), and virtual monochromatic images at 70 keV (VMI70) and 140 keV (VMI140) were reconstructed, and the HU values of each reference material were measured. The difference in HU values was larger when the phantom was scanned using the half dose with wrapping with rubber (strong beam-hardening effect) compared with the full dose without the rubber (reference condition), and the difference was larger as the electron density increased. For SECT, the difference in HU values against the reference condition measured by the DSCT (3.2 ± 5.0 HU) was significantly smaller (p < 0.05) than that using DLCT with 120 kVp (22.4 ± 23.8 HU), DLCT with 140 kVp (11.4 ± 12.8 HU), and FKSCT (13.4 ± 14.3 HU). The respective difference in HU values in the VMI70 and VMI140 measured using the DSCT (10.8 ± 17.1 and 3.5 ± 4.1 HU) and FKSCT (11.5 ± 21.8 and 5.5 ± 10.4 HU) were significantly smaller than those measured using the DLCT120 (23.1 ± 27.5 and 12.4 ± 9.4 HU) and DLCT140 (22.3 ± 28.6 and 13.1 ± 11.4 HU). The HU values and the susceptibility to beam-hardening effects varied widely depending on the DECT scanners.

Dose length product and outcome of CT fluoroscopy-guided interventions using a new 320-detector row CT scanner with deep-learning reconstruction and new bow-tie filter.

OBJECTIVES: To investigate the dose length product (DLP) and outcomes of CT fluoroscopy (CTF)-guided interventions using a novel 320-detector row CT scanner with deep-learning reconstruction (DLR) and a new bow-tie filter (i.e., Aquilion ONE Prism Edition) and compare with a 320-detector row CT system without DLR and the new bow-tie filter (i.e., Aquilion ONE Vision Edition) (Vision). METHODS: CTF-guided interventions performed using Prism and Vision were retrospectively investigated in terms of the technical success rates, clinical success rates of biopsies, complications, DLPs of total CT scans (total DLPs) from February 2019 to January 2021. The total CT scans included pre-interventional CT scans, CTF scans during the CTF-guided procedure, additional CT scans for additional treatment, CTF scans for additional treatment, and post-interventional CT scans. RESULTS: In this study, 87 and 85 CTF-guided interventions were performed using Vision (Vision group) and Prism (Prism group), respectively. There was no significant difference in the technical success rate (96.6% vs 98.8%, p = 0.621), clinical success rate of biopsies (92.9% vs 93.4%, p = 1.000), and minor (8.0% vs 7.1%, p = 0.807) and major (0% vs 3.5%, p = 0.119) complications between the Prism and Vision groups. The total DLPs for the Prism group were significantly lower than those for the Vision group regardless of the procedure (278 vs 548 mGy*cm, p < 0.001, in the biopsy and 246 vs 667 mGy*cm, p < 0.001, in the drainage and aspiration). CONCLUSIONS: CTF-guided interventions on Prism reduce the total DLP without performance degradation of the intervention. ADVANCES IN KNOWLEDGE: The total DLPs of biopsies and drainages/aspirations in the Prism group decreased by 49 and 63%, respectively.

CT-guided bone biopsy using electron density maps from dual-energy CT.

Computed tomography (CT) -guided bone biopsy is a diagnostic procedure performed on the musculoskeletal system with a high diagnostic yield and low complications. However, CT-guided bone biopsy has the disadvantage that it is difficult to confirm the presence of tumor cells during the biopsy procedure. Recently, the clinical benefits of dual-energy CT (DECT) over single-energy CT have been revealed. DECT can provide material decomposition images including calcium suppression images, and effective atomic number (Zeff) and electron density (ED) maps. ED maps have been reported to indicate cellularity. A 61-year-old woman with a history of breast cancer surgery was admitted to our hospital and underwent a CT-guided bone biopsy of the right ilium using ED maps. As a result, she was diagnosed with breast cancer metastases of intertrabecular bone. A comparison of ED maps with a pathological specimen revealed that high ED values occurred exclusively in the tumor area with high cellularity. This study indicates that ED maps produced using DECT may have potential utility in the accurate identification of metastases with high cellularity in bone lesions.

First experience of efficacy and radiation exposure in 320-detector row CT fluoroscopy-guided interventions.

OBJECTIVE: We investigated the efficacy and exposure to radiation in 320-detector row computed tomography fluoroscopy-guided (CTF-guided) interventions. METHODS: We analysed 231 320-detector row CTF-guided interventions (207 patients over 2 years and 6 months) in terms of technical success rates, clinical success rates, complications, scanner settings, overall radiation doses (dose-length product, mGy*cm), patient doses of peri-interventional CT series, and interventional CT (including CTF), as a retrospective cohort study. The relationships between patient radiation dose and interventional factors were assessed using multivariate analysis. RESULTS: Overall technical success rate was 98.7% (228/231). The technical success rates of biopsies, drainages, and aspirations were 98.7% (154/156), 98.5% (66/67), and 100% (8/8), respectively. The clinical success rate of biopsies was 93.5% (146/156). All three major complications occurred in chest biopsies. The median total radiation dose was 522.4 (393.4-819.8) mGy*cm. Of the total radiation dose, 87% was applied during the pre- and post-interventional CT series. Post-interventional CT accounted for 24.4% of the total radiation dose. Only 11.4% of the dose was applied by CTF-guided intervention. Multilinear regression demonstrated that male sex, body mass index, drainage, intervention time, and helical scan as post-interventional CT were significantly associated with higher dose. CONCLUSION: The 320-detector row CTF interventions achieved a high success rate. Dose reduction in post-interventional CT provides patient dose reduction without decreasing the technical success rates. ADVANCES IN KNOWLEDGE: This is the first study on the relationship between various interventional outcomes and patient exposure to radiation in 320-detector row CTF-guided interventions, suggesting a new perspective on dose reduction.

Low psoas muscle index is a poor prognostic factor for lower gastrointestinal perforation: a single-center retrospective cohort study.

BACKGROUND: Various body composition indices have been reported as prognostic factors for different cancers. However, whether body composition affects prognosis after lower gastrointestinal tract perforation requiring emergency surgery and multidisciplinary treatment has not been clarified. This study examined whether body composition evaluations that can be measured easily and quickly from computed tomography (CT) are useful for predicting prognosis. METHODS: Subjects comprised 64 patients diagnosed with perforation at final diagnosis after emergency surgery for a preoperative diagnosis of lower gastrointestinal tract perforation and penetration. They were divided into a survival group and a non-survival (in-hospital mortality) group and compared. Body composition indices (psoas muscle index (PMI); psoas muscle attenuation (PMA); subcutaneous adipose tissue index (SATI); visceral adipose tissue index (VATI); visceral-to-subcutaneous fat area ratio (VSR)) were measured from preoperative CT. Cross-sectional psoas muscle area at the level of the 3rd lumbar vertebra was quantified. Optimal cut-off values were calculated using receiver operating characteristic curve analysis. Poor prognostic factors were investigated from multivariate logistic regression analyses that included patient factors, perioperative factors, intraoperative factors, and body composition indices as explanatory variables. RESULTS: The cause of perforation was malignant disease in 12 cases (18.7%), and benign disease in 52 cases (81.2%). The most common cause was diverticulum of the large intestine. Emergency surgery for the 64 patients led to survival in 52 patients and death in 12 patients. On multivariate logistic regression analysis, independent predictors of poor prognosis were Sequential Organ Failure Assessment score (odds ratio 1.908; 95% confidence interval (CI) 1.235-3.681; P = 0.0020) and PMI (odds ratio 13.478; 95%CI 1.342-332.690; P = 0.0252). The cut-off PMI was 4.75 cm2/m2 for males and 2.89 cm2/m2 for females. Among survivors, duration of hospitalization was significantly longer in the low PMI group (29 days) than in the high PMI group (22 days, p = 0.0257). CONCLUSIONS: PMI is easily determined from CT and allows rapid evaluation of prognosis following lower gastrointestinal perforation.

Urethra-sparing high-intensity focused ultrasound for localized prostate cancer: Functional and oncological outcomes.

OBJECTIVES: To evaluate longitudinal changes in urinary function and quality of life, and the oncological outcomes of patients treated with urethra-sparing high-intensity focused ultrasound for localized prostate cancer. METHODS: Patients with negative findings in the urethra and the anterior urethral zone using transrectal ultrasound-guided targeted biopsies, and magnetic resonance imaging, received urethra-sparing or whole-gland high-intensity focused ultrasound as the primary therapy for localized prostate cancer without transurethral resection of the prostate. Longitudinal changes in urinary function and quality of life, and the oncological outcomes of the patients were analyzed retrospectively. RESULTS: The median follow-up times for urethra-sparing and whole-gland high-intensity focused ultrasound were 36 and 30 months, respectively. Comparing the patients treated with urethra-sparing high-intensity focused ultrasound (n = 45) with those treated with whole-gland high-intensity focused ultrasound (n = 65), there were significant differences in the International Prostate Symptom Score (P = 0.014) at 3 months, International Prostate Symptom Score quality of life (P = 0.033) at 3 months, maximum urinary flow rate (mL/s; at 3 months, P = 0.010; at 6 months, P = 0.038) and residual urine volume (mL; at 3 months, P < 0.0001; at 6 months, P = 0.016; at 12 months, P = 0.028). For quality of life, there were significant differences in Functional Assessment of Cancer Therapy - General (at 3 months, P = 0.022) and Functional Assessment of Cancer Therapy - Prostate (at 3 months, P = 0.028; at 6 months, P = 0.034). There were no significant differences in oncological outcomes regarding negative biopsy rates on follow up (91% vs 92%; P = 0.8) or biochemical disease-free survival rates (86.7% vs 89.2%; P = 0.7). CONCLUSIONS: Urethra-sparing high-intensity focused ultrasound might prevent prolonged bladder outlet obstruction, and could be a treatment option for localized prostate cancer.

Morphological analysis of the effects of intraoperative transrectal compression of the prostate during high-intensity focused ultrasound for localized prostate cancer.

OBJECTIVES: To evaluate the effects of transrectal compression of the prostate for intra-operative prostatic swelling and intraprostatic point shift during high-intensity focused ultrasound treatment of localized prostate cancer. METHODS: Patients treated with whole-gland high-intensity focused ultrasound as primary monotherapy for localized prostate cancer were enrolled in the study. Using the standard and compression method, the volumes of degassed water in the balloon covering the high-intensity focused ultrasound probe were 50 mL and 80-160 mL, respectively. To identify prostatic swelling and shift during high-intensity focused ultrasound and the volume occupied by the non-enhanced area, three-dimensional prostate models were reconstructed using ultrasound and contrast-enhanced magnetic resonance imaging. RESULTS: In comparison with the standard (n = 40) and compression (n = 48) methods, intraoperative increase in the prostate volume (21% vs 5.3%; P = 0.044), intraprostatic point shift (4 mm vs 2 mm, P = 0.040 in the transition zone; 3 mm vs 0 mm; P = 0.001 in the peripheral zone) and the volume occupied by the non-enhanced area (89% vs 96%; P = 0.001) were significantly suppressed. The biochemical disease-free survival rate in patients treated using the compression method was significantly improved relative to the standard method (92.6% vs 76.5%; P = 0.038). Regarding complications, there was no significant difference in the rate of urethral stricture (P = 0.9), urinary tract infection (P = 0.9), incontinence (P = 0.3), erectile dysfunction (P = 0.9) or recto-urethral fistula between the patients treated using the standard and compression methods. CONCLUSIONS: Intraoperative transrectal compression suppresses intraoperative increase in the prostate volume and intraprostatic point shift during high-intensity focused ultrasound, having the potential to achieve precise whole-gland and lesion-targeted focal therapy.

Dynamic cross-sectional changes of the middle cerebral artery in atherosclerotic stenosis detected by 3·0-Tesla MRI.

OBJECTIVES: Atherosclerotic stenosis of the middle cerebral artery (MCA) is one of the causes of ischemic stroke, but aside from investigations using magnetic resonance angiography (MRA), studies evaluating stenosis are rare. The purpose of this study was to assess dynamic changes of MCA cross section between the systolic and diastolic phases in patients with cerebral infarction using 3·0-Tesla magnetic resonance imaging (3T MRI). METHODS: We assessed 12 stroke patients with M1 stenosis in the MCA and 12 healthy volunteers. We measured MCA cross sections (proximal/distal to stenosis and on the stenosis) in the systolic and diastolic phases by synchronizing imaging with heartbeats, as well as the maximum flow velocity by using cine-phase contrast (PC) MRI. Each patient also underwent conventional MRA. RESULTS: Differences in cross sections between systolic and diastolic phases were significantly smaller in the stenosed artery compared to the distal (P < 0·05) and proximal areas (P < 0·01) in stroke patients. The difference in maximal blood velocity between systolic and diastolic phases at the M1 stenosis was significantly larger than that in the area proximal to the stenosis (P < 0·05). DISCUSSION: We clearly demonstrated dynamic cross-sectional changes in the stenotic areas by 3T MRI, suggesting hemodynamic shear stress, which may further enhance MCA atherosclerosis.

[Problem of spectral attenuated with inversion recovery fat suppression method with respiratory-gated].

The purpose of this study was to investigate the effect of fat suppression when we use respiratory-gated spectral attenuated with inversion recovery (SPAIR) method with respiratory-gated. We experimented on phantom and in-vivo study using simulated wave of respiratory-gated SPAIR at 1.5 tesla and 3.0 tesla. As a result, the effect of fat suppression becomes wrong with longer intervals of inspiration and expiration by wave of respiratory-gated. The signal intensity also varies with each slice. This result had the same trend on phantom and in-vivo study. The longitudinal magnetization of fat becomes a stable state when SPAIR pulse is shot more than once. However, the SPAIR method with respiratory-gated collect signal before the longitudinal magnetization of fat to be stable state, and fat suppression effect becomes bad, because the inversion time does not match the null point of the fat. Therefore, when we use SPAIR method with respiratory-gated it always causes bad fat suppression.

Preoperative virtual simulation of adrenal tumors.

BACKGROUND: Retroperitoneal endoscopic adrenalectomy (EA) is recognized as a principal procedure for benign adrenal tumors. However, a limited visual field and a narrow working space make this approach difficult, particularly in cases of obese patients or small tumors. Using multidetector row CT (MD-CT), this study investigated the use of preoperative virtual simulation (PVS) to identify tumor and central vein locations for EA, and verified these findings during EA surgery. PATIENTS AND METHODS: The study enrolled 11 cases comprising 10 adrenal adenomas and one ACTH-independent macronodular adrenal hyperplasia admitted to Jichi Medical University Hospital, Tochigi, Japan, between November 2003 and October 2006. Patients were evaluated in a lateral bending position using MD-CT. 3D PVS images of ribs, vertebrae, kidneys, and adrenal tumors were generated and compared with real images obtained during EA. RESULTS: The PVS images clearly showed the relative locations of the adrenal tumor, kidney, and adjacent anatomical structures. These locations were verified during EA. The central vein was identified in the PVS images in all cases. Information derived from the PVS images assisted in the performance of EA surgery. CONCLUSIONS: Preoperative 3D-simulation images using MD-CT contributed to the safety and efficiency of performing EAs.