Evidence map›Paper›PMID 42021183›Full record

ArticleBMC medical imaging2026

Geometric feature analysis for identifying and characterizing normal variations on chest radiographs.

Shinichi Fujimoto, Takeshi Hara, Masato Tanaka, Hideki Uesaka, Harumi Itoh, Toyohiko Sakai, Toshiki Tateishi, Tetsuya Tsujikawa

Abstract read
In one paragraph

Article in BMC medical imaging, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

0numbers the graph read from it
0cells of the map it votes in
0citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

8 authors.

Shinichi FujimotoRadiological Center, University of Fukui Hospital, Yoshida-gun, 910-1193, Japan.
Takeshi HaraDepartment of Electronic and Computer Engineering, Gifu University, Gifu City, 501-1193, Japan.
Masato TanakaMedical Education Support Center, University of Fukui, Yoshida-gun, 910-1193, Japan.
Hideki UesakaMedical Education Support Center, University of Fukui, Yoshida-gun, 910-1193, Japan.
Harumi ItohDepartment of Electronic and Computer Engineering, Gifu University, Gifu City, 501-1193, Japan.
Toyohiko SakaiDepartment of Radiology, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuoka-Shimoaizuki, Eiheiji-cho, Yoshida-gun, 910-1193, Japan.
Toshiki TateishiRadiological Center, University of Fukui Hospital, Yoshida-gun, 910-1193, Japan.
Tetsuya TsujikawaDepartment of Radiology, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuoka-Shimoaizuki, Eiheiji-cho, Yoshida-gun, 910-1193, Japan. awaji@u-fukui.ac.jp.

Funding

JST, CREST JPMJCR21D4
6 · The paper itself

Abstract

purposeTo develop and evaluate a quantitative method using geometric features of anatomical shadows on chest X-rays (CXRs) to identify normal variant cases and to elucidate the factors characterizing these variations. MATERIALS AND

methodsThis study included 548 normal CXRs confirmed by CT within one month. Shadows of six key anatomical structures (trachea, aorta, right atrium, left ventricle, right/left diaphragm domes) were manually labeled. Geometric features—center of gravity (x, y), length (l), and count (c)—were calculated for each label after image standardization. Cases with features (x, y, l) in the upper/lower 2.5% distribution or with label count (c) ≥ 2 were defined as normal variants. Associated factors were investigated using corresponding CT images and patient age/BMI.

resultsNormal variants were identified in 291/548 cases (53.1%). Analysis of 532 outlier feature instances showed associations with adjacent anatomical structures (41.0%, e.g., vertebrae, pulmonary veins, accessory fissures), spinal curvature/vertebral levels (14.2%, trachea only), and significant correlations with age and/or BMI (44.8%). Age was primarily linked to aortic variations, while BMI correlated more with cardiac and diaphragmatic variations. Notable findings included partial right atrial shadow disappearance near the middle lobe pulmonary vein and a wide normal superior tracheal range (C6-Th2).

conclusionThis quantitative geometric feature method successfully identifies and characterizes a wide range of normal variations on CXRs. It effectively linked feature outliers to specific anatomical structures and patient factors like age and BMI. This approach provides a foundation for automated large-scale analysis, potentially enhancing radiological training and diagnostic accuracy.

Indexed as

Radiographic Image Interpretation, Computer-AssistedRadiography, ThoracicTomography, X-Ray ComputedAdolescentAdultAgedAged, 80 and overAortaChildChild, PreschoolDiaphragmFemaleHeart AtriaHumansInfantMaleAnatomical variationChest radiographyComputed tomographyGeometric feature analysisImage standardizationNormal variationOutlier detectionQuantitative analysis

Identifiers

PMID42021183
PMCPMC13235210

What OpenQuestion holds

Textmetadata
LicenceCC BY-NC-ND
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.