The essence of the Japan Radiological Society/Japanese College of Radiology Imaging Guideline

Auto-evaluation of skull radiograph accuracy using unsupervised anomaly detection

BACKGROUND

Radiography plays an important role in medical care, and accurate positioning is essential for providing optimal quality images. Radiographs with insufficient diagnostic value are rejected, and retakes are required. However, determining the suitability of retaking radiographs is a qualitative evaluation.

OBJECTIVE

To evaluate skull radiograph accuracy automatically using an unsupervised learning-based autoencoder (AE) and a variational autoencoder (VAE). In this study, we eliminated visual qualitative evaluation and used unsupervised learning to identify skull radiography retakes from the quantitative evaluation.

METHODS

Five skull phantoms were imaged on radiographs, and 1,680 images were acquired. These images correspond to two categories: normal images captured at appropriate positions and images captured at inappropriate positions. This study verified the discriminatory ability of skull radiographs using anomaly detection methods.

RESULTS

The areas under the curves for AE and VAE were 0.7060 and 0.6707, respectively, in receiver operating characteristic analysis. Our proposed method showed a higher discrimination ability than those of previous studies which had an accuracy of 52%.

CONCLUSIONS

Our findings suggest that the proposed method has high classification accuracy in determining the suitability of retaking skull radiographs. Automation of optimal image consideration, whether or not to retake radiographs, contributes to improving operational efficiency in busy X-ray imaging operations.

Diagnostic Performance of Preoperative Imaging in Endometrial Cancer

BACKGROUND

Endometrial cancer is one of the most common gynecological malignancies. Because the findings mentioned in radiogram interpretation reports issued by diagnostic radiologists influence treatment strategies, we aimed to evaluate the diagnostic accuracy of preoperative computed tomography (CT) and magnetic resonance imaging (MRI) interpretation results in clinically relevant settings.

METHODS

The clinical records of patients diagnosed with endometrial cancer treated at Tohoku University Hospital from January 2012 to December 2021 were reviewed. The preoperative and pathologically estimated cancer stages were compared based on the results mentioned in the radiogram interpretation report.

RESULTS

The preoperative and postoperative cancer stages were concordant in 70.0% of the patients. By contrast, the cancer stage was underdiagnosed and overdiagnosed in 21.7% and 8.2% of the patients, respectively. The sensitivities of MRI for deep myometrial invasion, cervical stromal invasion, vaginal invasion, and adnexal metastasis were 65.1%, 58.2%, 33.3%, and 18.4%, respectively. The sensitivity and specificity for pelvic lymph node metastasis using a combination of CT and MRI were 40.9% and 98.4%, respectively. Those for para-aortic lymph node metastases using CT were 37.0% and 99.5%, respectively.

CONCLUSIONS

The low sensitivity observed in this study clarified the limitations of preoperative diagnostic performance in current clinical practice.

Changes in the clinical spectrum of pediatric moyamoya disease over 40 years

OBJECTIVE

To investigate the chronological changes in the clinical presentation and long-term prognosis of pediatric-onset moyamoya disease in our institute over 40 years.

METHODS

We evaluated 282 pediatric-onset (≤ 15 years old) moyamoya disease patients who visited our institute from 1981 to 2020 (divided into the former period, 1981-2000, and the latter period, 2001-2020). Differences in the clinical presentation and the long-term outcome were compared between the periods. Multivariate analysis was also performed to reveal the risk factors for poor long-term outcomes.

RESULTS

Compared to the former period, the total number of patients, the onset age and both the number of patients with family history and relatively older patients without symptoms or with headache were greater in the latter period (p < 0.05). The number of patients with poor long-term outcomes was significantly lower in the latter period (24.9% vs. 6.7%, p < 0.01). Multivariate analysis revealed that stroke onset, late cerebrovascular events and postoperative complications were independent risk factors for poor long-term outcomes (odds ratio = 31.4, 40.8 and 5.4, respectively).

CONCLUSIONS

Over the last 40 years, the number of pediatric moyamoya disease patients has increased, especially in relatively older patients with mild presentation and favorable long-term outcomes. In clinical studies, these chronological changes and the inclusion period of the participants need to be accounted for. Whether the increased diagnostic rate in the recent era has led to a decrease in late cerebrovascular events and favorable outcomes throughout life remains unknown and should be evaluated in the future.

Development of an Algorithm to Differentiate Uterine Sarcoma from Fibroids Using MRI and LDH Levels

BACKGROUND

This study aimed to establish an evaluation method for detecting uterine sarcoma with 100% sensitivity using MRI and serum LDH levels.

METHODS

One evaluator reviewed the MRI images and LDH values of a total of 1801 cases, including 36 cases of uterine sarcoma and 1765 cases of uterine fibroids. The reproducibility of the algorithm was also examined by four evaluators with different imaging experience and abilities, using a test set of 61 cases, including 14 cases of uterine sarcoma.

RESULTS

From the MRI images and LDH values of 1801 cases of uterine sarcoma and uterine fibroids, we found that all sarcomas were included in the group with a high T2WI and either a high T1WI, an unclear margin, or high LDH values. In addition, when cases with DWI were examined, all sarcomas had high DWI. Among the 36 sarcoma cases, the group with positive findings for T2WI, T1WI, margins, and serum LDH levels all had a poor prognosis (p = 0.015). The reproducibility of the algorithm was examined by four evaluators and the sensitivity of sarcoma detection ranged from 71% to 93%.

CONCLUSION

We established an algorithm to distinguish uterine sarcoma if tumors in the myometrium with low T2WI and DWI are present.

Fat Distribution Patterns and Future Type 2 Diabetes

Fat accumulation in the liver, pancreas, skeletal muscle, and visceral bed relates to type 2 diabetes (T2D). However, the distribution of fat among these compartments is heterogenous and whether specific distribution patterns indicate high T2D risk is unclear. We therefore investigated fat distribution patterns and their link to future T2D. From 2,168 individuals without diabetes who underwent computed tomography in Japan, this case-cohort study included 658 randomly selected individuals and 146 incident cases of T2D over 6 years of follow-up. Using data-driven analysis (k-means) based on fat content in the liver, pancreas, muscle, and visceral bed, we identified four fat distribution clusters: hepatic steatosis, pancreatic steatosis, trunk myosteatosis, and steatopenia. In comparisons with the steatopenia cluster, the adjusted hazard ratios for incident T2D were 4.02 (95% CI 2.27-7.12) for the hepatic steatosis cluster, 3.38 (1.65-6.91) for the pancreatic steatosis cluster, and 1.95 (1.07-3.54) for the trunk myosteatosis cluster. The clusters were replicated in 319 German individuals without diabetes who underwent MRI and metabolic phenotyping. The distribution of the glucose area under the curve across the four clusters found in Germany was similar to the distribution of T2D risk across the four clusters in Japan. Insulin sensitivity and insulin secretion differed across the four clusters. Thus, we identified patterns of fat distribution with different T2D risks presumably due to differences in insulin sensitivity and insulin secretion.

Universal Access to Advanced Imaging and Healthcare Protection: UHC and Diagnostic Imaging

Universal Health Coverage (UHC) is a set of principles adopted by the World Health Organization (WHO) aimed to guarantee access to primary care for the entire world population through a range of essential health services without neglecting the diagnostic aspect. Italy is one of the signatory states, which means that diagnostic services should be appropriated and exigible throughout the national territory equally. Our research analyzed and identified the main criticalities in terms of age, territorial distribution, and technological and health appropriateness of installed Computed Tomography (CT) needed to meet the principles of UHC. Data analyzed in our study were published by Assobiomedica at the end of 2016 and by COCIR, which included and investigated the installed fleet of diagnostic equipment in the Italian sanitary system and in various European countries. The 6th point of the Alma Ata Declaration defines the concept of “primary health care”, which includes the importance of the diagnostic phase in the Italian health care system to provide Essential Levels of Assistance (LEA). It is clear from our studies that the technology at the national level is not adequate to satisfy the UHC principles or the European criteria, with negative effects on the diagnostic standards and on advanced screenings. This study conducted on the installed CTs in Italy at the end of 2016 confirms the persistence of progressive aging that has been recorded for several years in the health facilities of the country and suggests incentive policies for the replacement of obsolete equipment, which represent a form of investment rather than a cost, due to the nature of the expenditure itself, one-off and amortizable over time.

Longitudinal association of fatty pancreas with the incidence of type-2 diabetes in lean individuals: a 6-year computed tomography-based cohort study

BACKGROUND

Only a few studies have longitudinally evaluated whether fatty pancreas increases the risk of type-2 diabetes (T2D), and their results were inconsistent. Fatty pancreas is closely linked to overweight and obesity, but previous studies did not exclude overweight or obese individuals. Therefore, in this cohort study, we investigated the association between fatty pancreas and T2D incidence in lean individuals.

METHODS

Between 2008 and 2013, 1478 nondiabetic lean individuals (i.e. body-mass index < 25 kg/m²) underwent health examinations including computed tomography (CT) and were followed for a median of 6.19 years. Fatty pancreas was evaluated by a histologically-validated method using pancreas attenuation (Hounsfield units [HU]) on CT at baseline; lower pancreas attenuation indicates more pancreatic fat. To detect incident T2D, we used fasting plasma glucose, HbA1c, and self-reports of prescribed anti-diabetes medications. Odds ratios (OR) for the association between pancreas attenuation and incident T2D were estimated using logistic regression models adjusted for likely confounders.

RESULTS

T2D occurred in 61 participants (4.13%) during the follow-up period. Lower pancreas attenuation (i.e. more pancreatic fat) at baseline was associated with incident T2D (unadjusted OR per 10 HU lower attenuation: 1.56 [95% CI 1.28-1.91], p < 0.001). The multivariable-adjusted analysis revealed a similar association (adjusted OR per 10 HU lower attenuation: 1.32 [95% CI 1.06-1.63], p = 0.012).

CONCLUSIONS

T2D was likely to develop in lean individuals with the fatty pancreas. Among people who are neither obese nor overweight, the fatty pancreas can be used to define a group at high risk for T2D.

Delayed recognition of childhood arterial ischemic stroke

BACKGROUND

Few population-based surveys of childhood arterial ischemic stroke (AIS) have been conducted in Asian countries. The aim of this study was to investigate the clinical features, time to diagnosis, and prognosis of childhood AIS in a population-based cohort in Japan.

METHODS

Children aged 29 days-15 years 11 months old, residing in the Aichi Prefecture of Japan with radiologically confirmed AIS during 2010-2014, were identified retrospectively through questionnaires. We analyzed 40 children (23 boys, 17 girls; median age, 7 years 3 months), and collected time interval information of 26 patients. The time from clinical onset to first physician assessment and the time to AIS diagnosis were calculated.

RESULTS

The most common presentation was paralysis or paresis in 27 patients (71%). No underlying disorders or possible trigger factors were identified in 14 patients (35%). The median time from symptom onset to first physician assessment was 2.9 h. The median time from symptom onset to the confirmed AIS diagnosis was 27.0 h. The diagnosis of AIS was made in the first 6 h after onset of symptoms in 27% of patients for whom the time was available. Radiological diagnosis took longer than 24 h in 54% of these patients.

CONCLUSIONS

Long in-hospital delays exist in the diagnosis of AIS in children, likely due to lack of awareness of stroke by doctors. Further efforts to increase public and physician awareness of childhood stroke are needed to ensure early diagnosis and treatment.

Large hospital variation in the utilization of Post-procedural CT to detect pulmonary embolism/Deep Vein Thrombosis in Patients Undergoing Total Knee or Hip Replacement Surgery: Japanese Nationwide Diagnosis Procedure Combination Database Study

OBJECTIVE

The purpose of the study was to investigate variation in the use of in-hospital CT for venous thromboembolism (VTE) detection after total knee or hip replacement (TKR/THR) among surgical patients, using a nationwide Japanese in-hospital administrative database.

METHODS

This retrospective study using a national administrative database (4/2012-3/2013) extracted patients who underwent TKR/THR surgeries at hospitals meeting the annual case-volume threshold of ≥ 30. Hospitals were categorized into three equally sized groups by frequency of postoperative CT use (low, middle, and high CT use group) to compare baseline patient-level and hospital-level characteristics. To further investigate between-hospital variation in CT usage, we fitted a hierarchical logistic regression model including hospital-specific random intercepts and fixed patient- and hospital-level effects. The intra class correlation coefficient was used to measure the amount of variability in CT use attributable to between-hospital variation.

RESULTS

A total of 39,127 patients discharged from 447 hospitals met the inclusion criteria. The median hospital stay was 25 days (interquartile range, 20 - 32) and 7,599 (19.4%) patients underwent CT for VTE. CT utilization varied greatly among the hospitals; the crude frequency ranged from 0 to 100 % (median, 7.3 %; interquartile range, 1.8 - 18.3 %). After adjustment for known hospital- and patient-level factors related to CT use, 47 % of the variation in CT use remained attributable to the behavior of individual hospitals.

CONCLUSION

We observed large inter hospital variability in the utilization of post-procedure CT for VTE detection in this Japanese TKR/THR cohort, suggesting that CT utilization is not optimized across the nation.

ADVANCES IN KNOWLEDGE

We observed significant variability in the utilization of post-procedure CT for VTE detection among inpatients who underwent TKR/THR surgeries in a large sample of Japanese hospitals. The large variation suggests that CT utilization is not optimized across the nation, and that there may be potential overutilization of the technology in the highest CT use hospitals.

Association between pancreatic fat and incidence of metabolic syndrome: a 5-year Japanese cohort study

BACKGROUND AND AIM

Previous cross-sectional studies showed that pancreatic fat was associated with metabolic syndrome. However, no longitudinal study has evaluated whether people with high pancreatic fat are likely to develop future metabolic syndrome. This study investigated the association between baseline pancreatic fat and metabolic syndrome incidence.

METHODS

In 2008-2009, 320 participants without metabolic syndrome underwent health checks, which included unenhanced computed tomography, and were followed up annually for 4-5 years. Baseline pancreatic fat amounts were evaluated using a histologically validated method that measured differences between pancreas and spleen attenuations on computed tomography. The participants were divided into low (reference), intermediate, and high pancreatic fat groups based on pancreas and spleen attenuation tertiles. Metabolic syndrome incidence was evaluated annually over a median follow-up period of 4.99 (interquartile range, 4.88-5.05) years, in accordance with the 2009 harmonized criteria. Risk ratios (RRs) for the association between baseline pancreatic fat amounts and metabolic syndrome incidence were estimated using Poisson regression models adjusted for age, sex, body mass index, liver fat, pre-metabolic syndrome, cigarette use, alcohol use, and physical activity.

RESULTS

Metabolic syndrome incidence was 30.6% (98/320). Pancreatic fat was associated with an increased incidence of metabolic syndrome, based on a univariate analysis (RRs [95% confidence interval], 3.14 [1.74-5.67] and 3.96 [2.23-7.03] in the intermediate and high pancreatic fat groups, respectively). The association remained statistically significant in the multivariate analysis (RR [95% confidence interval], 2.04 [1.14-3.64] and 2.30 [1.28-4.14] for the same groups, respectively).

CONCLUSIONS

Pancreatic fat predicts the future risk of metabolic syndrome.

Radiologist involvement is associated with reduced use of MRI in the acute period of low back pain in a non-elderly population

PURPOSE

To test the hypothesis that "acute-period" lumbar MRI in non-elderly patients with low back pain is less frequently performed at clinics/hospitals with greater involvement of full-time radiologists in the imaging workflow.

METHODS

In a national-level claims database, we identified 14,819 non-elderly patients (mean age: 38.7±8.0 years) who visited clinics/hospitals for low back pain in 2013-2015. We classified the clinics/hospitals into four groups based on the level of full-time radiologist involvement and MRI ownership, and compared the frequency of acute-period lumbar MRI using hierarchical logistic regression analysis.

RESULTS

Patients visiting facilities without a full-time radiologist (n=2105) were significantly (p<0.001) more likely to undergo acute-period MRI than those visiting facilities with ≥1 radiologist partially managing imaging workflow (level-1, n=491) or ≥1 radiologist intensively involved in imaging workflow (level-2, n=1190) (15.7% vs. 6.9% and 7.3%; adjusted odds ratio of no-radiologist versus level-2: 2.93, p=0.018). No difference was observed between level-1 and level-2 involvement.

CONCLUSIONS

Facilities with no full-time radiologist were more likely to perform acute-period MRI to assess for low back pain, while no difference was seen between facilities with varying levels of radiologist involvement in the imaging workflow. Radiologist involvement may contribute to optimal utilisation of medical imaging.

KEY POINTS

• Lumbar MRI was more frequently performed at facilities without full-time radiologists. • Full-time radiologists may play an important role in appropriate utilisation of imaging. • Frequency of MRI was similar between moderate and intensive radiologist involvement.