Geographic Distribution of CT, MRI and PET Devices in Japan: A Longitudinal Analysis Based on National Census Data

Worldwide differences in surgeon intraoperative practices for cochlear implantation

OBJECTIVE

To characterize practice patterns of intraoperative imaging and/or functional confirmation of cochlear implant electrode location worldwide.

METHODS

A cross-sectional survey of otolaryngologists performing cochlear implantation was conducted between March 1 and May 6, 2023. Participants were recruited worldwide using an international otologic society membership email list and at professional meetings. Ninety-seven of the 125 invited participants (78%) completed the survey. Participants were categorized by continent.

RESULTS

North American surgeons use intraoperative X-rays more frequently than surgeons in Europe and Asia (p < 0.001). Otolaryngologists in Europe and Asia more frequently use no intraoperative imaging (p = 0.02). There is no regional difference between the intraoperative use of electrophysiologic instruments. European and Asian surgeons implant MED-EL devices (p = 0.012) more frequently than North American surgeons, who more frequently use Cochlear Corporation devices (p = 0.003). MED-EL use is related to less frequent intraoperative X-ray use (p = 0.02). Advanced Bionics use is related to more frequent intraoperative CT use (p = 0.03). No significant association existed between years of practice, number of cochlear implantation surgeries performed yearly, volume of pediatric CI practice, and use of intraoperative tools.

CONCLUSION

Intraoperative practice for radiologic and functional verification of cochlear implant electrode positioning varies worldwide. Practice guidelines may help establish a standard of care for cochlear implantation.

The impact of the Iranian health transformation plan policy on equitable access to medical imaging services in West Iran

OBJECTIVE

Equity in the delivery of health services, including diagnostic imaging, is crucial to achieving universal health coverage. The Health Transformation Plan (HTP), launched in 2014, represents a major healthcare policy to improve the quality and accessibility of healthcare services. This study aimed to explore the impact of the HTP on equity in the access to medical imaging in Lorestan province, located in west Iran, from 2014 to 2023. Annual growth rates (AGR) of imaging devices were calculated, whilst equity assessment of medical imaging distribution was carried out by means of the Gini coefficient and the Lorenz curve per 100,000 population. The latter was generated using the cumulative distribution of imaging devices, as well as the cumulative population ratio.

RESULTS

Between 2014 and 2023, the number of imaging devices has increased threefold. The AGR of installing CT and MRI scanners in Lorestan province increased between 2014 and 2023. The Gini coefficients increased from 0.12 for CT and 0.16 for MRI in 2014 to 0.33 in 2023 for both devices. This indicates a decrease in equity in access to these fundamental health technologies despite the increase in their figures. Policymakers should better allocate medical equipment based on the specific health needs of different regions throughout Iran.

The diagnostic value of dual-layer CT in the assessment of lymph nodes in lymphoma patients with PET/CT as a reference standard

This study aimed to evaluate the diagnostic performances of dual-layer CT (DLCT) for the identification of positive lymph nodes (LNs) in patients with lymphoma and retrospectively included 1165 LNs obtained by biopsy from 78 patients with histologically proven lymphoma, who underwent both pretreatment DLCT and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). According to 18F-FDG PET/CT findings as a reference standard, cases were categorized into the LN-negative and LN-positive groups. LNs were then randomly divided at a ratio of 7:3 into the training (n = 809) and validation (n = 356) cohorts. The patients' clinical characteristics and quantitative parameters including spectral curve slope (λHU), iodine concentration (IC) on arterial phase (AP) and venous phase (VP) images were compared between the LN-negative and LN-positive groups using Chi-square test, t-test or Mann-Whitney U test for categorical variables or quantitative parameters. Multivariate logistic regression analysis with tenfold cross-validation was performed to establish the most efficient predictive model in the training cohort. The area under the curve (AUC) was used to evaluate the diagnostic value of the predictive model, and differences in AUC were determined by the DeLong test. Moreover, the predictive model was validated in the validation cohort. Repeatability analysis was performed for LNs using intraclass correlation coefficients (ICCs). In the training cohort, long diameter (LD) had the highest AUC as an independent factors compared to other parameter in differentiating LN positivity from LN negativity (p = 0.006 to p < 0.001), and the AUC of predictive model jointly involving LD and λHU-AP was significantly elevated (AUC of 0.816, p < 0.001). While the AUC of predictive model in the validation cohort was 0.786. Good to excellent repeatability was observed for all parameters (ICC > 0.75). The combination of DLCT with morphological and functional parameters may represent a potential imaging biomarker for detecting LN positivity in lymphoma.

Evaluation of extracellular volume by computed tomography is useful for prediction of prognosis in dilated cardiomyopathy

Cardiac computed tomography (CT) is useful for the screening of coronary artery stenosis, and extracellular volume fraction (ECV) analysis by CT using new dedicated software is now available. Here, we evaluated the utility of ECV analysis using cardiac CT to predict patient prognosis in cases with dilated cardiomyopathy (DCM). We analyzed 70 cases with DCM and cardiac computed tomography (CT) with available late-phase images. We evaluated the ECV of the left ventricular myocardium (LVM) using commercially available software (Ziostation 2, Ziosoft Inc, Japan). ECV on LVM was 33.96 ± 5.04%. Major adverse cardiac events (MACE) occurred in 21 cases (30%). ECV of the LVM on CT, endo-systolic volume, and rate of significant valvular disease were significantly higher in cases with MACE than in those without (37.16 ± 5.91% vs. 32.59 ± 3.95%, 194 ± 109 vs. 138 ± 78 ml and 57% vs. 20%, all P values < 0.05). LVEF was significantly lower in cases with MACE than in those without (23 ± 8 vs. 31 ± 11%, P = 0.0024). The best cut-off value of ECV on LVM for prediction of MACE was 32.26% based on receiver operating characteristics analysis. Cases with ECV ≥ 32.26% had significantly higher MACE based on Kaplan-Meier analysis (P = 0.0032). Only ECV on LVM was an independent predictor of MACE based on a multivariate Cox proportional hazards model (P = 0.0354). Evaluation of ECV on LVM by CT is useful for predicting MACE in patients with DCM.

Early Diagnosis and Surgical Intervention Within 3 Weeks From Symptom Onset Are Associated With Prolonged Survival of Patients With Glioblastoma

BACKGROUND

Glioblastoma (GBM) is a rapidly growing and most life-threatening malignant brain tumor. The significance of early treatment to the clinical outcomes of patients with GBM is unclear.

OBJECTIVE

To determine whether early diagnosis and surgery improve the preoperative and postoperative Karnofsky performance status (KPS) and prognosis of patients with GBM.

METHODS

Data of isocitrate dehydrogenase-wildtype patients with GBM treated at our institution between January 2010 and December 2019 were reviewed. Patients were classified into early or late diagnosis groups with a threshold of 14 days from initial symptoms. In addition, patients were divided into early, intermediate, and late surgery groups with thresholds of 21 and 35 days. Representative symptoms and patient prognoses were examined.

RESULTS

Of 153 patients, 72 and 81 were classified into the early and late diagnosis groups. The median tumor volume was significantly smaller in the former group. The proportion of patients with preoperative KPS scores 90 was 48.6% and 29.6% in the early and late diagnosis groups ( P = .016). The early, intermediate, and late surgery groups included 43, 24, and 86 patients. The median overall survival was significantly longer in the early surgery group than in the late surgery group (28.4 vs 18.7 months, P = .006). Multivariate analysis demonstrated that significant predictors of shorter survival included extent of tumor resection (partial or biopsy), preoperative and postoperative KPS 60, and O6-methylguanine-DNA-methyltransferase promoter status (unmethylated).

CONCLUSION

Early diagnosis within 2 weeks and surgical interventions within 3 weeks from the symptom onset are associated with prolonged patient survival. Early GBM treatment will benefit patients with GBM.

99m Tc bone scintigraphy does not affect preoperative workup for patients with potentially resectable esophageal squamous cell carcinoma

Background

^99mTc bone scintigraphy (BS) is the mainstay and most widely used technique in evaluation of bone metastasis (BM) in China. This study aimed to investigate the value of ^99mTc BS in preoperative workup for patients with potentially resectable (cT_1−4aN₀₋₃) esophageal squamous cell carcinoma (ESCC).

Methods

This prospective cross‐section clinical trial (ChiCTR1800020304) enrolled a total of 385 patients with ESCC diagnosed at thoracic surgery clinic from October 2018 to September 2020. All patients were diagnosed with stage cT_1−4aN₀₋₃ and were potential candidates for surgical resection. BS was performed preoperatively and the treatment strategy was changed after confirmation of BM. The primary endpoint was the rate of change of the treatment regimen because of BM, while the secondary endpoint was the rate of positive BS findings.

Results

Out of the 385 patients, only two (0.5%) changed their treatment regimen because of BM. The rate of positive BS findings was 1%, while two patients (0.5%) had false‐positive or false‐negative results. The BS diagnostic performance for BM was sensitivity 50%, specificity 99.5%, positive predictive value 50%, negative predictive value 99.5%, and accuracy 99.0%. There was no significant difference in BM in relation to age, sex, tumor location or clinical stage.

Conclusion

Our data demonstrated that ^99mTc bone scintigraphy does not significantly affect the preoperative workup in patients with potentially resectable ESCC, especially in early clinical stage patients.

Adoption of large-scale medical equipment: the impact of competition in the German inpatient sector

The availability of large-scale medical equipment such as computed tomography (CT), magnet resonance imaging (MRI) and positron emission tomography (PET) scanners has increased rapidly worldwide over the last decades. Among OECD countries, Germany ranks high according to the number of imaging technologies and their applications per inhabitant. In contrast to other countries, there is no active governmental planning of large-scale medical equipment. We therefore investigated whether and how the adoption and distribution of CT, MRI and PET scanners in the German inpatient sector is subject to competition. Using a linear-probability model, we additionally examined the impact of regional, hospital- and population-based factors. In summary, our results indicate that the adoption rate by hospital sites decreases with the number of other sites being already equipped with the respective device and their proximity. However, the effect presumably depends on the technologies' stage within the diffusion process. No influence regarding the amount of state subsidies could be identified. Furthermore, hospital size and university status strongly affect the adoption.

How Much Tumor Volume Is Responsible for Development of Clinical Symptoms in Patients With Convexity, Parasagittal, and Falx Meningiomas?

Purpose: Meningiomas are the most common primary intracranial neoplasms and clinical symptom appearance depends on their volume and location. This study aimed to identify factors that influence clinical symptoms and to determine a specific threshold tumor volume for the prediction of symptomatic progression in patients with convexity, parasagittal, and falx meningiomas.

Materials and Methods: We retrospectively studied patients with radiologically suspected convexity, parasagittal, or falx meningiomas at our institution.

Results: The data of three hundred thirty-three patients were analyzed. We further divided patients into two groups based on clinical symptoms: an asymptomatic group (250 cases) and a symptomatic group (83 cases). Univariate analysis revealed significant differences between the groups in terms of sex (p = 0.002), age at the time of volumetric analysis (p < 0.001), hyperintense lesions on T2-weighted images (p = 0.029), peritumoral edema (p < 0.001), maximum tumor diameter (p < 0.001), and tumor volume (p < 0.001). Further multivariate analysis revealed significant differences between the groups in terms of age at the time of volumetric analysis (p = 0.002), peritumoral edema (p < 0.001), and tumor volume (p < 0.001). The receiver operating characteristic curve revealed a threshold tumor volume of 21.1 ml for predicting whether a patient would develop symptoms (sensitivity 0.843, specificity 0.880, an area under the curve 0.919 [95% confidence interval: 0.887–0.951]).

Conclusion: We identified factors predictive of clinical symptoms in patients with convexity, parasagittal, and falx meningiomas and determined the first-ever threshold tumor volume for predicting symptomatic progression in such patients.

Biosorption of different gadolinium (Gd) complexes from water by Eichhornia crassipes (water hyacinth)

Many studies have demonstrated the Eichhornia crassipes (water hyacinth) potency in removing heavy metals, but the plant's potential for sorption of gadolinium (Gd) has not yet been investigated. In this study, water hyacinth was grown in a glass container for 30 days with either GdCl₃ or Gd-based contrast agent (GBCA; gadoterate) with water obtained from the Tone River. On the day 30, the Gd concentration in both the water and the plants was measured by mass spectrometry (ICP-MS). After 30 days, 98.5% of GdCl₃ in the water had been absorbed by the roots, and 3.5% of Gd was transferred to the leaves. On the other hand, the water hyacinth roots absorbed only 12% of the gadoterate. When exposed to 5 mg/L of GdCl₃, the roots of water hyacinth may effectively remove Gd ions in the aquatic environment, with no visible effect on the general health of the plant. However, the water hyacinth roots did not absorb GBCA. This may result in higher accumulation of Gd in the aqueous environment. The GBCA may be broken down by environmental factors and negatively affect the marine ecosystem.

Automated approach for segmenting gross tumor volumes for lung cancer stereotactic body radiation therapy using CT-based dense V-networks

The aim of this study was to develop an automated segmentation approach for small gross tumor volumes (GTVs) in 3D planning computed tomography (CT) images using dense V-networks (DVNs) that offer more advantages in segmenting smaller structures than conventional V-networks. Regions of interest (ROI) with dimensions of 50 × 50 × 6-72 pixels in the planning CT images were cropped based on the GTV centroids when applying stereotactic body radiotherapy (SBRT) to patients. Segmentation accuracy of GTV contours for 192 lung cancer patients [with the following tumor types: 118 solid, 53 part-solid types and 21 pure ground-glass opacity (pure GGO)], who underwent SBRT, were evaluated based on a 10-fold cross-validation test using Dice's similarity coefficient (DSC) and Hausdorff distance (HD). For each case, 11 segmented GTVs consisting of three single outputs, four logical AND outputs, and four logical OR outputs from combinations of two or three outputs from DVNs were obtained by three runs with different initial weights. The AND output (combination of three outputs) achieved the highest values of average 3D-DSC (0.832 ± 0.074) and HD (4.57 ± 2.44 mm). The average 3D DSCs from the AND output for solid, part-solid and pure GGO types were 0.838 ± 0.074, 0.822 ± 0.078 and 0.819 ± 0.059, respectively. This study suggests that the proposed approach could be useful in segmenting GTVs for planning lung cancer SBRT.

Geographical and Temporal Distribution of Radiologists, Computed Tomography and Magnetic Resonance Scanners in Croatia

The aim of the study was to analyse the temporal and geographic distribution of radiologists, computed tomography and magnetic resonance scanners in Croatia. In this observational study we estimated radiologists’ number per 100,000 population for 1997, 2006, and 2017 and compared private and public CT and MR scanners between 2011 and 2018. We analyzed the availability of radiologists and scanners, and the relationship between the radiological workforce and economic strength among counties. The workforce increased significantly from 1997 to 2017 and was associated with economic strength categories in 2017. In 2018, there were more CT scanners in the public sector, while MR scanners were distributed evenly. In 2011, there was similar distribution of CT and MR between sectors, while in 2018 there were significantly more public CT scanners. Counties with a medical school had significantly more radiologists and MR scanners. The high-to-low ratios per CT and MR were 11 and 8.2, suggesting inequality of health care. Croatia significantly increased its radiological workforce; however, cross-county inequality remained. Counties with higher economic strength and medical schools have better availability of radiologists and equipment. To ensure the sustainable activity of the health care system, a precise estimate of supply and demand of radiology services is needed.

Development of a dynamic imaging method for gravitropism in pea sprouts using clinical magnetic resonance imaging system

Although magnetic resonance imaging (MRI) is a useful technique, only a few studies have investigated the dynamic behavior of small subjects using MRI owing to constraints such as experimental space and signal amount. In this study, to acquire high-resolution continuous three-dimensional gravitropism data of pea (Pisum sativum) sprouts, we developed a small-bore MRI signal receiver coil that can be used in a clinical MRI and adjusted the imaging sequence. It was expected that such an arrangement would improve signal sensitivity and improve the signal-to-noise ratio (SNR) of the acquired image. All MRI experiments were performed using a 3.0-T clinical MRI scanner. An SNR comparison using an agarose gel phantom to confirm the improved performance of the small-bore receiver coil and an imaging experiment of pea sprouts exhibiting gravitropism were performed. The SNRs of the images acquired with a standard 32-channel head coil and the new small-bore receiver coil were 5.23±0.90 and 57.75±12.53, respectively. The SNR of the images recorded using the new coil was approximately 11-fold higher than that of the standard coil. In addition, when the accuracy of MR imaging that captures the movement of pea sprout was verified, the difference in position information from the optical image was found to be small and could be used for measurements. These results of this study enable the application of a clinical MRI system for dynamic plant MRI. We believe that this study is a significant first step in the development of plant MRI technique.

Whole Body 3.0 T Magnetic Resonance Imaging in Lymphomas: Comparison of Different Sequence Combinations for Staging Hodgkin's and Diffuse Large B Cell Lymphomas

To investigate the diagnostic value of different whole-body magnetic resonance imaging (WB-MRI) protocols for staging Hodgkin and diffuse-large B-cell lymphomas (HL and DLBCL), twenty-two patients (M/F 12/10, median age 32, range 22-87, HL/DLBCL 14/8) underwent baseline WB-MRI and 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET) fused with computed tomography (CT) scan 18F-FDG-PET-CT. The 3.0 T WB-MRI was performed using pre-contrast modified Dixon (mDixon), T2-weighted turbo-spin-echo (TSE), diffusion-weighted-imaging (DWI), dynamic-contrast-enhanced (DCE) liver/spleen, contrast-enhanced (CE) lung MRI and CE whole-body mDixon. WB-MRI scans were divided into: (1) "WB-MRI DWI+IP": whole-body DWI + in-phase mDixon (2) "WB-MRI T2-TSE": whole-body T2-TSE (3) "WB-MRI Post-C": whole-body CE mDixon + DCE liver/spleen and CE lung mDixon (4) "WB-MRI All ": the entire protocol. Two radiologists evaluated WB-MRIs at random, independently and then in consensus. Two nuclear-medicine-physicians reviewed 18F-FDG PET-CT in consensus. An enhanced-reference-standard (ERS) was derived using all available baseline and follow-up imaging. The sensitivity and specificity of WB-MRI protocols for nodal and extra-nodal staging was derived against the ERS. Agreement between the WB-MRI protocols and the ERS for overall staging was assessed using kappa statistic. For consensus WB-MRI, the sensitivity and specificity for nodal staging were 75%, 98% for WB-MRI DWI+IP, 76%, 98% for WB-MRI Post-C, 83%, 99% for WB-MRI T2-TSE and 87%, 100% for WB-MRI All. The sensitivity and specificity for extra-nodal staging were 67% 100% for WB-MRI DWI+IP, 89%, 100% for WB-MRI Post-C, 89%, 100% for WB-MRI T2-TSE and 100%, 100% for the WB-MRI All. The consensus WB-MRI All read had perfect agreement with the ERS for overall staging [kappa = 1.00 (95% CI: 1.00-1.00)]. The best diagnostic performance is achieved combining all available WB-MRI sequences.

The Haleem-Botchu classification: a novel CT-based classification for lumbar foraminal stenosis

PURPOSE

No clinical CT-based classification system is currently in use for lumbar foraminal stenosis. MRI scanners are not easily available, are expensive and may be contraindicated in an increasing number of patients. This study aimed to propose and evaluate the reproducibility of a novel CT-based classification for lumbar foraminal stenosis.

MATERIALS AND METHODS

The grading was developed as four grades: normal foramen-Grade 0, anteroposterior (AP)/superoinferior (SI) (single plane) fat compression-Grade 1, both AP/SI compression (two planes) without distortion of nerve root-Grade 2 and Grade 2 with distortion of nerve root-Grade 3. A total of 800 lumbar foramen of a cohort of 100 random patients over the age of 60 who had undergone both CT and MRI scans were reviewed by two radiologists independently to assess agreement of the novel CT classification against the MRI-based grading system of Lee et al. Interobserver(n = 400) and intraobserver agreement(n = 160) was also evaluated. Agreement analysis was performed using the weighted kappa statistic.

RESULTS

A total of 100 patients (M:F = 45:55) with a mean age of 68.5 years (range 60-83 years were included in the study. The duration between CT and MRI scans was 98 days (range 0-540, SD-108). There was good correlation between CT and MRI with kappa scores (k = 0.81) and intraobserver kappa of 0.89 and 0.98 for the two readers.

CONCLUSION

The novel CT-based classification correlates well with the MRI grading system and can safely and accurately replace it where required.

Incorporation of a computer-aided vessel-suppression system to detect lung nodules in CT images: effect on sensitivity and reading time in routine clinical settings

PURPOSE

To evaluate whether a computer-aided vessel-suppression system improves lung nodule detection in routine clinical settings.

MATERIALS AND METHODS

We used computer software that automatically suppresses pulmonary vessels on chest CT while preserving pulmonary nodules. Sixty-one chest CT images were included in our study. Three radiologists independently read either standard CT images alone or both computer-aided CT and standard CT images randomly to detect a pulmonary nodule ≥ 4 mm in diameter. After an interval of at least 15 days to avoid recall bias, the three radiologists interpreted the counterpart images of the same patients. The reference standard was decided by an expert panel. The primary endpoint was sensitivity. The secondary endpoint was interpretation time.

RESULTS

The average sensitivity improved with computer-aided CT (72% for standard CT vs. 84% for computer-aided CT, p = 0.02). There was no difference in the false-positive rate (21% for both standard CT and computer-aided CT, p = 0.98). Although the average reading time was 9.5% longer for computer-aided plus standard CT compared with standard CT alone, the difference was not significant (p = 0.11).

CONCLUSION

Vessel-suppressed CT images helped radiologists to improve the sensitivity of pulmonary nodule detection without compromising the false-positive rate.

Geographic distribution and utilisation of CT and MRI services at public hospitals in Myanmar

BACKGROUND

Diagnosis by computed tomography (CT) and magnetic resonance imaging (MRI) is important for patient care. However, the geographic distribution and utilisation of these machines in countries with limited resources, such as Myanmar, have not been sufficiently studied. Therefore, this study aims to identify the geographic distribution and utilisation of CT and MRI services at public hospitals in Myanmar.

METHODS

This nationwide, cross-sectional study was conducted at 43 public hospitals in Myanmar. Data were collected retrospectively using a prepared form from 1st January 2015 to 31st December 2017 at public hospitals in Myanmar. A descriptive analysis was performed to calculate the number of CT and MRI units per million population in each state and region of Myanmar. The distribution of CT and MRI units was assessed using the Lorenz curve and Gini coefficient, which are indicators of inequality in distribution.

RESULTS

In total, 45 CT and 14 MRI units had been installed in public hospitals in Myanmar by 2017. In total, 205,570 CT examinations and 18,981 MRI examinations have been performed within the study period. CT units per million population in 2017 varied from 0.30 in Rakhine State to 3.22 in Kayah State. However, MRI units were available only in public hospitals in five states/regions. The Gini coefficient for CT and MRI was 0.35 and 0.69, respectively. An upward trend in the utilisation rate of CT and MRI was also observed during the study period, especially among patients aged between 36 and 65 years.

CONCLUSIONS

Throughout Myanmar, CT units were more equally distributed than MRI units. CT and MRI units were mostly concentrated in the Yangon and Mandalay Regions, where the population density is higher. The geographic distribution and utilisation rate of CT and MRI units varied among states, regions, and patients' age group. However, the utilisation rates of CT and MRI increased annually in all states and regions during the review period. The Ministry of Health and Sports in Myanmar should consider the utilisation and population coverage of CT and MRI as an important factor when there will be procurement of those medical equipment in the future.

Evaluation of magnetic resonance imaging artifacts caused by fixed orthodontic CAD/CAM retainers-an in vitro study

Objectives

Magnetic resonance imaging (MRI) image quality can be severely impaired by artifacts caused by fixed orthodontic retainers. In clinical practice, there is a trend towards using computer-aided design/computer-aided manufacturing (CAD/CAM) retainers. This study aimed to quantify MRI artifacts produced by these novel CAD/CAM retainers.

Material and methods

Three CAD/CAM retainers and a stainless-steel retainer (“Twistflex”; clinical reference standard) were scanned in vitro at 3-T MRI using a high-resolution 3D sequence. The artifact diameters and three-dimensional artifact volumes (AV) were determined for all mandibular (AV_mand) and maxillary (AV_max) retainers. Moreover, the corresponding ratio of artifact volume to retainer volume (AV/RV_mand, AV/RV_max) was calculated.

Results

Twistflex caused large artifact volumes (AV_mand: 13530 mm³; AV_max: 15642 mm³; AV/RV_mand: 2602; AV/RV_max: 2235). By contrast, artifact volumes for CAD/CAM retainers were substantially smaller: whereas artifact volumes for cobalt–chromium retainers were moderate (381 mm³; 394 mm³; 39; 31), grade-5 titanium (110 mm³; 126 mm³; 12; 12) and nickel–titanium (54 mm³; 78 mm³; 12; 14) both produced very small artifact volumes.

Conclusion

All CAD/CAM retainers caused substantially smaller volumes of MRI artifacts compared to Twistflex. Grade-5 titanium and nickel–titanium CAD/CAM retainers showed the smallest artifact volumes.

Clinical relevance

CAD/CAM retainers made from titanium or nickel–titanium may not relevantly impair image quality in head/neck and dental MRI. Artifacts caused by cobalt–chromium CAD/CAM retainers may mask nearby dental/periodontal structures. In contrast, the large artifacts caused by Twistflex are likely to severely impair diagnosis of oral and adjacent pathologies.

Work-style reform and use of information and communication technology among diagnostic radiologists in Japan: results of the 2018 JRS/JCR joint survey

PURPOSE

The purpose of this study was to investigate recent trends in work-style reform and the use of information and communication technology (ICT) among board-certified diagnostic radiologists in Japan.

MATERIALS AND METHODS

We conducted online questionnaire surveys of board-certified radiologists of the Japan Radiological Society (JRS) and registered training institutions. Completed surveys were obtained from 1192 radiologists and 275 training institutions (response rates of 25.5% and 38.1%, respectively). Respondents were assured of confidentiality.

RESULTS

13.5% (134/991) of full-time radiologists and 56.7% (89/157) of part-time radiologists had shifted some of their work to teleradiology at home. In addition, 52.9% (83/157) of part-time radiologists and 27.3% (12/44) of board-certified individuals who had stopped working as radiologists responded that they would consider starting full-time work in hospitals, if teleradiology at home was permitted as part of full-time work. Furthermore, 16.7% of training institutions (46/275) had introduced teleradiology systems for radiologists, and 47.2% (108/229) of the remaining training institutions wanted to introduce teleradiology systems in the future.

CONCLUSION

Teleradiology using ICT is already a part of Japanese radiologists' workload. Work-style reform may progress with the use of ICT, such as part-time radiologists, and board-certified individuals who stop working as radiologists, becoming full-time radiologists.

Dynamic contrast-enhanced computed tomography for the diagnosis of solitary pulmonary nodules: a systematic review and meta-analysis

INTRODUCTION

A systematic review and meta-analysis were performed to determine the diagnostic performance of dynamic contrast-enhanced computed tomography (DCE-CT) for the differentiation between malignant and benign pulmonary nodules.

METHODS

Ovid MEDLINE and EMBASE were searched for studies published up to October 2018 on the diagnostic accuracy of DCE-CT for the characterisation of pulmonary nodules. For the index test, studies with a minimum of a pre- and post-contrast computed tomography scan were evaluated. Studies with a reference standard of biopsy for malignancy, and biopsy or 2-year follow-up for benign disease were included. Study bias was assessed using QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies). The sensitivities, specificities, and diagnostic odds ratios were determined along with 95% confidence intervals (CIs) using a bivariate random effects model.

RESULTS

Twenty-three studies were included, including 2397 study participants with 2514 nodules of which 55.3% were malignant (1389/2514). The pooled accuracy results were sensitivity 94.8% (95% CI 91.5; 96.9), specificity 75.5% (69.4; 80.6), and diagnostic odds ratio 56.6 (24.2-88.9). QUADAS 2 assessment showed intermediate/high risk of bias in a large proportion of the studies (52-78% across the domains). No difference was present in sensitivity or specificity between subgroups when studies were split based on CT technique, sample size, nodule size, or publication date.

CONCLUSION

DCE-CT has a high diagnostic accuracy for the diagnosis of pulmonary nodules although study quality was indeterminate in a large number of cases.

KEY POINTS

• The pooled accuracy results were sensitivity 95.1% and specificity 73.8% although individual studies showed wide ranges of values. • This is comparable to the results of previous meta-analyses of PET/CT (positron emission tomography/computed tomography) diagnostic accuracy for the diagnosis of solitary pulmonary nodules. • Robust direct comparative accuracy and cost-effectiveness studies are warranted to determine the optimal use of DCE-CT and PET/CT in the diagnosis of SPNs.

The Diagnostic Process for the Evaluation of Acute Abdominal Pain by Resident Trainees in Japan: A Cross-sectional Study

Objective Acute abdominal pain (AAP) of diverse etiology is a common chief complaint of patients who present to the emergency department (ED). AAP may pose a diagnostic challenge to physicians in training. We aimed to evaluate whether or not resident trainee doctors examine patients presenting with AAP in a Japanese acute-care hospital following Kendall's diagnostic algorithm. Methods We conducted a retrospective medical chart review from January 2015 to December 2016. Patients Patients ≥50 years old who presented to the ED within 7 days of the onset of AAP who were evaluated by residents at the ED of an acute care hospital were enrolled in this study. Patients transported by ambulance and referred from other hospitals and classified as level 1 or 2 according to the Japanese version of the Canadian Triage and Acuity Scale were excluded. Data, including the clinical history, location and character of pain, and age and gender of patients as well as the level of experience of residents, were abstracted from charts. We evaluated the concordance rate between the actual diagnostic process followed by residents and Kendall's diagnostic algorithm for AAP. Results We analyzed 466 patients (mean age 67.6 years) in the study who were evaluated and diagnosed by 123 residents. The concordance rate between the diagnostic procedures performed by residents and those suggested by Kendall's diagnostic algorithm was 61.2%. A low concordance rate was observed among patients with peritoneal signs, shock or toxic appearance (25.0%), suggested acute coronary syndromes (ACS) (55.1%), epigastric or right upper-quadrant pain (52.8%), and left upper-quadrant pain (55.6%). Abdominal ultrasonography is one of the recommended examinations for patients with signs of peritoneal irritation, shock or toxic appearance, right lower-quadrant pain, and left upper- or lower-quadrant pain, but the rates were relatively low at 25.0%, 34.4%, 31.8%, and 26.7%, respectively. Conclusion Abdominal ultrasonography required by Kendall's diagnostic algorithm was not performed appropriately in patients with symptoms and signs of peritonitis, shock or toxic appearance, right lower-quadrant pain, and left upper- or lower-quadrant pain or in female patients by resident trainees. Our findings underscore the importance of providing resident doctors with focused training concerning ultrasonography by attending physicians.

The Risk of Developing Secondary Central Nervous System Tumors After Diagnostic Irradiation From Computed Tomography in Pediatrics: A Literature Review

BACKGROUND

Advanced diagnostic imaging has provided tremendous benefits; however, increased use of ionizing radiation modalities such as cranial computed tomography (CT) may be associated with an increased risk of developing central nervous system tumors.

METHODS

A literature review identified studies published for more than the last 50 years from 1968 to 2018 that explored the association between head CT scans and developing central nervous system tumors in pediatrics. We reviewed seven studies that described and analyzed the risk of brain tumors.

RESULTS

A positive correlation between exposure to CT scans and developing central nervous system tumors was evident in all cohorts. The strength of the association varied across the studies. Exclusion of patients with predisposing factors to central nervous system tumors was examined in four studies with a decreased risk to develop central nervous system tumors noted in three studies. Two studies reported nonsignificant reduction in the excess relative risk per milliGray of brain dose after adjusting for predisposing factors, whereas the reduction was significant in one study. The frequency of CT exposure was proportional to the risk of developing tumors in two studies although not significantly maintained in two other studies. Gender had no significant effect on the central nervous system tumor risk. The calendar year at the time of imaging showed decreasing risk in those exposed to CT in more recent years compared with prior decades.

CONCLUSIONS

Prospective epidemiologic studies are needed to examine the precise carcinogenic effect of exposure to ionizing radiation and help tailor further preventive measures.

Diffusion of advanced medical imaging technology, CT, and MRI scanners, in Iran: A qualitative study of determinants

BACKGROUND

Low-income and middle-income countries have a lot of problems in providing the financial, human, and capital resources for advanced medical imaging technologies (AMITs). Proper distribution of such expensive equipment might increase access to these services and enhance the quality and efficiency of health care. The present study aimed to identify the factors affecting the diffusion of AMITs including CT and MRI in Iran.

METHODS

This is a qualitative research conducted in 2017. A number of purposively chosen policy makers and managers from Ministry of Health, medical universities, hospitals, health insurance, and vendor companies were approached for face-to-face and semistructured interviews. Data analysis was done using thematic analysis method.

RESULTS

Three categories of influential factors were identified, including contextual, stakeholder related, and situational factors. With regards to the stakeholders, the ministry and physicians played the most important role in the diffusion process of the AMITs. Health insurance organizations and vendor companies played a minor role in distribution of the equipment. Application of political pressure by the authorities on the Ministry of Health to issue licenses for the acquisition of AMITs was taken as the most important factor and the greatest challenge in the diffusion of devices.

CONCLUSION

The results sought to assist health system authorities to manage diffusion of AMITs effectively and assign an equitable access to the expensive resources. The diffusion management together with utilization management could largely improve efficiency and cost containment. Medical technology diffusion management de facto needs policy instruments in both supply and demand sides.

Association between number of institutions with coronary computed tomography angiography and regional mortality ratio of acute myocardial infarction: a nationwide ecological study using a spatial Bayesian model

Background

Coronary computed tomography angiography (CTA) has demonstrated high diagnostic accuracy for detection of coronary artery stenosis, and healthcare providers can detect coronary artery disease in earlier stages before it develops into more serious clinical conditions such as acute myocardial infarction (AMI). We hypothesized that the mortality ratio of AMI in regions with a higher density of coronary CTA is lower than that in regions with a lower density of coronary CTA.

Methods

This ecological and cross-sectional study using secondary data targeted all secondary medical service areas (SMSAs) in Japan (n = 349). We obtained the numbers of cardiologists, institutions with coronary CTA, and institutions with a cardiac catheterization laboratory (CCL) as medical resources, socioeconomic factors, lifestyle factors, exercise habit factors, and AMI mortality data from a Japanese national database. We evaluated the association between the number of these medical resources and the standardized mortality ratio (SMR) of AMI in each SMSA using a hierarchical Bayesian model accounting for spatial autocorrelation (i.e., a conditional autoregressive model). We assumed a Poisson distribution for the observed number of AMI-related deaths and set the expected number of AMI-related deaths as the offset variable.

Results

The number of institutions with coronary CTA was negatively and significantly associated with the SMR of AMI (relative risk [RR] 0.900; 95% credible interval [CI] 0.848–0.953), while the SMR in each SMSA was not significantly associated with the number of either cardiologists (RR 0.997; 95% CI 0.988–1.004) or institutions with a CCL (RR 1.026; 95% CI 0.963–1.096).

Conclusions

We observed a significant association between the number of institutions with coronary CTA and the SMR of AMI. Effective allocation of coronary CTA in each region is recommended, and it would be important to clarify the standing position of coronary CTA in regional networking for AMI treatment in the future.

Electronic supplementary material

The online version of this article (10.1186/s12942-018-0133-0) contains supplementary material, which is available to authorized users.

Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences

As the number of magnetic resonance imaging (MRI) scanners and patients with medical implants is constantly growing, radiologists increasingly encounter metallic implant-related artifacts in MRI, resulting in reduced image quality. Therefore, the MRI suitability of implants in terms of artifact volume, as well as the development of pulse sequences to reduce image artifacts, are becoming more and more important. Here, we present a comprehensive protocol which allows for a standardized evaluation of the artifact volume of implants on MRI. Furthermore, this protocol can be used to analyze the vulnerability of different pulse sequences to artifacts. The proposed protocol can be applied to T1- and T2-weighted images with or without fat-suppression and all passive implants. Furthermore, the procedure enables the separate and three-dimensional identification of signal loss and pile-up artifacts. As previous investigations differed greatly in evaluation methods, the comparability of their results was limited. Thus, standardized measurements of MRI artifact volumes are necessary to provide better comparability. This may improve the development of the MRI suitability of implants and better pulse sequences to finally improve patient care.

Global and Japanese regional variations in radiologist potential workload for computed tomography and magnetic resonance imaging examinations

PURPOSE

To investigate the global variation in radiologist potential workload for CT and MRI examinations, and the regional variation in potential workload and extent of radiologists' involvement in CT and MRI examinations in Japan.

METHODS

"Radiologist potential workload" was defined as the annual number of CT plus MRI examinations divided by the total number of diagnostic radiologists. The extent of radiologists' involvement was measured as the proportion of CT and MRI examinations to which "Added-fees for Radiological Managements on Imaging-studies (ARMIs)" were applied among eligible examinations. Maximum variation was computed as the ratio of the highest-to-lowest values among the countries or Japanese prefectures.

RESULTS

The radiologist potential workload in Japan was 2.78-4.17 times higher than those in other countries. A maximum prefecture-to-prefecture variation was 3.88. The average percentage of CT plus MRI examinations with ARMI applied was 43.3%, with a maximum prefecture-to-prefecture variation of 3.97. Prefectures with more radiologists tended to have a higher extent of radiologists' involvement.

CONCLUSIONS

Japan had a far greater radiologist potential workload compared with other countries, with a large regional variation among prefectures. Prefectures with more radiologists tended to have a higher extent of radiologists' involvement in CT and MRI examinations.

Regional disparities in medical equipment distribution in the Slovak Republic - a platform for a health policy regulatory mechanism

BACKGROUND

This study aims to examine the localisation of selected parameters in the deployment and use of medical equipment in the Slovak Republic and to verify potential regional disparities. The study evaluates the benefits of an analytical platform for regulatory mechanisms in the healthcare system.

METHODS

The correspondence analysis is applied to the entire data set containing information regarding medical equipment distribution and mortality.

RESULTS

The results highlight regional differences in the use of medical equipment throughout the analysed period from 2008 to 2014. The total amount of medical equipment increased slightly to 9192 devices during the time span. In 2014, there was a significant decrease of 16.44%. Disparities are found in the frequencies and structure of medical equipment. In some regions, medical equipment is not present or is present in low numbers.

CONCLUSIONS

The results regarding regional disparities demonstrate the regional development of the amount of medical equipment. The deployment of medical equipment is not proportional, and not all of the analysed devices are available in each region. The tests also indicate the appropriateness of the amount of medical equipment and create a platform for further investigation. The results of the analysis suggest the unsuitable distribution of medical equipment throughout the Slovak regions, where there are significant regional disparities. These findings can serve as a monitoring platform to evaluate the accessibility and efficiency of medical equipment usage.

TRIAL REGISTRATION

No human participants were involved in the research.

Evaluation on equality and efficiency of health resources allocation and health services utilization in China

Background

China is faced with a daunting challenge to equality and efficiency in health resources allocation and health services utilization in the context of rapid economic growth. This study sought to evaluate the equality and efficiency of health resources allocation and health services utilization in China.

Methods

Demographic, economic, and geographic area data was sourced from China Statistical Yearbook 2012–2016. Data related to health resources and health services was obtained from China Health Statistics Yearbook 2012–2016. Furthermore, we evaluated the equality of health resources allocation based on Gini coefficient. Concentration index was used to measure the equality in utilization of health services. Data envelopment analysis (DEA) was employed to assess the efficiency of health resources allocation.

Results

From 2011 to 2015, the Gini coefficients for health resources by population ranged between 0.0644 and 0.1879, while the Gini coefficients for the resources by geographic area ranged from 0.6136 to 0.6568. Meanwhile, the concentration index values for health services utilization ranged from −0.0392 to 0.2110. Moreover, in 2015, 10 provinces (32.26%) were relatively efficient in terms of health resources allocation, while 7 provinces (22.58%) and 14 provinces (45.16%) were weakly efficient and inefficient, respectively.

Conclusions

There exist distinct regional disparities in the distribution of health resources in China, which are mainly reflected in the geographic distribution of health resources. Furthermore, the people living in the eastern developed areas are more likely to use outpatient care, while the people living in western underdeveloped areas are more likely to use inpatient care. Moreover, the efficiency of health resources allocation in 21 provinces (67.74%) of China was low and needs to be improved. Thus, the government should pay more attention to the equality based on geographic area, guide patients to choose medical treatment rationally, and optimize the resource investments for different provinces.

Assessing equity in the distribution of high-technology medical equipment in Guangxi: evidence from an ethnic minority region in Southern China

Background

High-technology medical equipment (HTME) are important health resources. However, there is unequal distribution of these equipment in favor of metropolis and well equipped health facilities. This study sought to examine the equity gaps in the distribution of HTME in Guangxi. The results of this study could shed light on the future HTME allocation in Guangxi Zhuang Autonomous Region.

Methods

Data related to HTME was sourced from a general investigation of all the hospitals of Guangxi. Concentration index was used to assess the equity status of HTME in Guangxi.

Results

Over all, the total amount of HTME in Guangxi had been increasing from 2011 to 2015, and the per million population HTME of five kinds were all increased at the same time. Meanwhile, the concentration indices ranged between 0.1020 and 0.4617. The five medical equipment were all concentrated among the rich.

Conclusions

The possession of SPECT per million population in Guangxi is lower than the national average level while it is superior to the national average level for CT, MRI, DSA and LA. The equity status in the distribution of the five medical equipment has deteriorated since 2011. In 2015, the equity status of CT was the best, while the equity status of MRI was the worst. Meanwhile, 45.1% of HTME were concentrated in Nanning, Guilin, and Liuzhou.

The effect of concentrating obstetrics services in fewer hospitals on patient access: a simulation

Background

In Japan, the number of obstetrics facilities has steadily decreased and the selection and concentration of obstetrics facilities is progressing rapidly. Obstetrics services should be concentrated in fewer hospitals to improve quality of care and reduce the workload of obstetricians. However, the impact of this intensification of services on access to obstetrics hospitals is not known. We undertook a simulation to examine how the intensification of obstetrics services would affect access to hospitals based on a variety of scenarios, and the implications for health policy.

Methods

The female population aged between 15 and 49 living within a 30-min drive of an obstetrics hospital was calculated using a Geographic Information System for three possible intensification scenarios: Scenario 1 retained facilities with a higher volume of deliveries without considering the geographic boundaries of Medical Service Areas (MSAs, zones of healthcare administration and management); Scenario 2 prioritized retaining at least one hospital in each MSA and then retained higher delivery volume institutions, while Scenario 3 retained facilities to maximize population coverage using location-allocation modeling. We also assessed the impact of concentrating services in academic hospitals and specialist perinatal medical centers (PMCs) alone.

Results

In 2011, 95.0 % of women aged 15–49 years lived within a 30-min drive of one of 1075 obstetrics hospitals. This would fall to 82.7 % if obstetrics services were intensified into academic hospitals and general and regional PMCs. If 55.0 % of institutions provided obstetrics services, the coverage would be 87.6 % in Scenario 1, whereas intensification based on access would achieve over 90.5 % coverage in Scenario 2 and 93.9 % in Scenario 3.

Conclusions

Intensification of obstetrics facilities impairs access, but a greater caseload and better staffing have the potential advantages of better clinical outcomes and reduced costs. It is essential to consult residents of hospital catchment areas when reorganizing clinical services; a simulation is a useful means of informing these important discussions.

Geographic Distribution of Radiologists and Utilization of Teleradiology in Japan: A Longitudinal Analysis Based on National Census Data

BACKGROUND

Japan has the most CT and MRI scanners per unit population in the world, and as these technologies spread, their geographic distribution is becoming equalized. In contrast, the number of radiologists per unit population in Japan is the lowest among OECD countries and their geographic distribution is unknown. Likewise, little is known about the use of teleradiology, which can compensate for the uneven distribution of radiologists.

METHODS

Based on the Survey of Physicians, Dentists and Pharmacists and the Static Survey of Medical Institutions by the Ministry of Health, Labour and Welfare, a dataset of radiologists and CT and MRI utilizations in each of Japan's 1811 municipalities was created. The inter-municipality equity of the number of radiologists was evaluated using Gini coefficient. Logistic regression analysis, based on Static Survey data, was performed to evaluate the association between hospital location and teleradiology use.

RESULTS

Between 2006 and 2012 the number of radiologists increased by 21.7%, but the Gini coefficient remained unchanged. The number of radiologists per 1,000 CT (MRI) utilizations decreased by 17.9% (1.0%); the number was highest in metropolis and lowest in town/village and the disparity has widened from 1.9 to 2.2 (1.6 to 2.0) times. The number of hospitals and clinics using teleradiology has increased (by 69.6% and 18.1%, respectively). Hospitals located in towns/villages (odds ratio 1.61; 95% confidence interval 1.26-2.07) were more likely to use teleradiology than those in metropolises.

CONCLUSIONS

Contrary to the CT and MRI distributions, radiologist distribution has not been evened out by the increase in their number; in other words, the distribution of radiologists was not affected by market-derived spatial competition force. As a consequence, the gap of the radiologist shortage between urban and rural areas is increasing. Teleradiology, which is one way to ameliorate this gap, should be encouraged.