In this study, we propose an automatic contour outlining method to measure the spatial resolution of homemade automatic tube current modulation (ATCM) phantom by outlining the edge contour of the phantom image, selecting the region of interest (ROI), and measuring the spatial resolution characteristics of computer tomography (CT) phantom image. Specifically, the method obtains a binarized image of the phantom outlined by an automated fast region convolutional neural network (AFRCNN) model, measures the edge spread function (ESF) of the CT phantom with different tube currents and layer thicknesses, and differentiates the ESF to obtain the line spread function (LSF). Finally, the values passing through the zeros are normalized by the Fourier transform to obtain the CT spatial resolution index (RI) for the automatic measurement of the modulation transfer function (MTF). In this study, this algorithm is compared with the algorithm that uses polymethylmethacrylate (PMMA) to measure the MTF of the phantom edges to verify the feasibility of this method, and the results show that the AFRCNN model not only improves the efficiency and accuracy of the phantom contour outlining, but also is able to obtain a more accurate spatial resolution value through automated segmentation. In summary, the algorithm proposed in this study is accurate in spatial resolution measurement of phantom images and has the potential to be widely used in real clinical CT images.
Phantoms, Imaging ; Tomography, X-Ray Computed/instrumentation* ; Algorithms ; Neural Networks, Computer ; Image Processing, Computer-Assisted/methods* ; Humans ; Polymethyl Methacrylate

OBJECTIVE: To define a safe distance range from the LC-Ⅱ screw trajectory to the apex of the greater sciatic notch based on pelvic CT measurements, and to clinically assess the feasibility of using this range under iliac oblique view combined with iliac tangential view fluoroscopy to guide screw insertion. METHODS: CT scans of 104 normal pelvises collected between January 2022 and February 2025 were analyzed. There were 52 males and 52 females, with a median age of 45.8 years (range, 19-76 years). The RadiAnt DICOM Viewer software was used to reconstruct coronal, sagittal, and axial sections of the potential LC-Ⅱ screw trajectory. The maximum safety distance (Dmax) and the optimal safety distance (Dopt) from this trajectory to the greater sciatic notch were measured on the coronal and sagittal views. A retrospective analysis was conducted on 21 patients with LC-Ⅱ type pelvic fractures treated with the LC-Ⅱ screws fixation. And the screws were placed within the pre-defined safe distance under guidance from the iliac oblique view and iliac tangential view. Postoperative CT scans were obtained to evaluate the accuracy of screw placement. RESULTS: Radiographic measurements from the 104 cases showed that Dmax ranged from 1.87 to 3.87 cm (mean, 2.79 cm), and Dopt ranged from 1.01 to 2.92 cm (mean, 1.84 cm). Both Dmax and Dopt were significantly greater in the males than in the females ( P>0.05). No significant difference was found between the left and right sides within the same gender ( P>0.05). All 21 patients successfully underwent fracture reduction and fixation, with a total of 23 LC-Ⅱscrews implanted. According to the Lonstein grading system, the screw placement accuracy was rated as excellent in 16 screws, good in 3, fair in 3, and poor in 1, with an excellent and good rate of 82.6%. CONCLUSION Utilizing a CT-defined safe distance range from the screw trajectory to the greater sciatic notch, and adhering to this range under iliac oblique view combined with iliac tangential view fluoroscopy, enables the accurate and precise placement of LC-Ⅱ screws.
Humans ; Male ; Female ; Middle Aged ; Bone Screws ; Adult ; Tomography, X-Ray Computed/methods* ; Aged ; Ilium/surgery* ; Pelvic Bones/diagnostic imaging* ; Fracture Fixation, Internal/instrumentation* ; Retrospective Studies ; Fluoroscopy ; Fractures, Bone/diagnostic imaging* ; Young Adult

OBJECTIVES: To develop a measurement software of lung compression degree to calculate the lung compression ratio in pneumothorax patients accurately and quickly, and then provide an objective assessment of damage degree in forensic clinical identification. METHODS: A volume calculation software was established according to the working principle of the CT instrument. CT data of 15 pneumothorax patients were selected as research objects. The lung compression ratio of pneumothorax patient was calculated by the lung compression volume calculation software of the CT instrument. Meanwhile, the lung compression ratio was also calculated by the developed volume calculation software. The lung compression ratio and operation time calculated by the two methods were analyzed statistically. Scatter plot graphs were draw based on related data, and the developed volume calculation software was verified. RESULTS: The difference between the lung compression ratios calculated by the two methods was not statistically significant, but showed a linear correlation （P<0.05）. The operation time of the developed volume calculation software was obviously shorter. CONCLUSIONS The volume calculation software developed in this study can calculate the lung compression degree of pneumothorax more conveniently and rapidly with easy accessibility, which shows an application value in the forensic practice.
Forensic Medicine/instrumentation* ; Humans ; Image Processing, Computer-Assisted/methods* ; Lung/diagnostic imaging* ; Pneumothorax ; Software ; Tomography, X-Ray Computed

OBJECTIVETo investigate the preoperative assessment value of spectral CT quantitative parameters in lymph node metastasis of gastric cancer.

METHODSFrom December 2013 to June 2015, clinical and image data of 86 patients with gastric cancer confirmed by gastroscope pathology undergoing preoperative enhanced CT were prospectively collected. Enhanced CT included nonenhanced CT of conventional 120 kVp mode, arterial phase (AP) and venous phase (VP) with GSI mode on Discover GSI CT scanner. The raw data were transferred to ADW4.6 workstation to reconstruct the monochromatic images at 70 keV and iodine-based images in AP and VP with 1.25 mm thickness. The short diameter, long diameter, ratio of short to long diameter, CT attenuation and iodine value of lymph nodes in each phase were measured and recorded. Pathology results were used as golden standard. The spectral CT quantitative parameters of positive and negative lymph nodes were compared by t test and the sensitivity and specificity analyses were performed by ROC curves. This clinical study registration number 81271573.

RESULTSAmong these 86 gastric cancer patients (53 male and 33 female), tumors of 28 cases were in upper part, of 12 cases in middle part, of 27 cases in distal part and of 19 cases involved two parts. Thirty-five cases were differentiated type and 51 cases were undifferentiated type. A total of 1 072 lymph nodes were found in operation, of which 412 nodes were positive and 660 were negative. Among 552 lymph nodes found in CT images, 338 nodes were positive and 214 were negative. Compared to negative lymph nodes, short diameter [(9.52±3.58) mm vs. (6.48±2.94) mm, t=4.639, P=0.000], ratio of short to long diameter (0.82±0.14 vs. 0.61±0.08, t=13.514, P=0.000), CT attenuation in precontrast [(20.44±6.77) Hu vs. (16.06±7.14) Hu, t=3.154, P=0.002], CT attenuation in AP[(61.71±11.78) Hu vs. (40.11±10.18) Hu, t=9.588, P=0.000], CT attenuation in VP[(71.34±13.03) Hu vs. (53.81±11.39) Hu, t=7.888, P=0.000], iodine value in AP [(16.17±4.22) 100 μg/cmvs. (8.03±3.10) 100 μg/cm, t=9.781, P=0.000], the iodine value in VP [(20.13±6.04) 100 μg/cmvs. (11.58±4.13) 100 μg/cm, t=10.147, P=0.000] of positive lymph nodes were greater. The long diameter was not significantly different between positive and negative lymph nodes [(11.71±5.63) mm vs. (10.64±3.20) mm, t=1.380, P=0.169]. The area under ROC curve of short diameter, ratio of short to long diameter, CT attenuation in precontrast, AP and VP, iodine value in AP and VP of lymph nodes was 0.600, 0.880, 0.648, 0.832, 0.755, 0.864, 0.835, respectively. Taking the ratio of short to long diameter over 0.72 as diagnosis standard, the sensitivity was 75.6% and the specificity was 93.5%. Taking the CT number in AP over 49.75 Hu, the sensitivity was 66.9% and the specificity was 88.8%. Taking the CT number in VP over 59.80 Hu, the sensitivity was 69.9% and the specificity was 77.6%. Taking the iodine value in AP over 9.65 (100 μg/cm), the sensitivity was 80.4% and the specificity was 82.2%. Taking the iodine value in VP over 15.65 (100 μg/cm), the sensitivity was 69.9% and the specificity was 86.9%. Combinong the ratio of short to long diameter with the iodine value in AP, the sensitivity was 95.2% and the specificity was 76.9%.

CONCLUSIONSThe ratio of short to long diameter, the iodine value and CT attenuation in AP and VP of lymph nodes in spectral CT are important criteria to evaluate the metastasis of gastric cancer. Combining the ratio of short to long diameter with the iodine value in AP can obviously improve the sensitivity.

Female ; Gastroscopy ; Humans ; Iodine Radioisotopes ; Lymph Nodes ; diagnostic imaging ; pathology ; Lymphatic Metastasis ; diagnostic imaging ; Male ; ROC Curve ; Sensitivity and Specificity ; Stomach Neoplasms ; diagnostic imaging ; Tomography, X-Ray Computed ; instrumentation ; methods

Oesophageal rupture is a life-threatening complication of balloon tamponade for bleeding oesophageal varices. We herein describe the clinical course and imaging findings in a 33-year-old Indian man who had a Sengstaken-Blakemore (SB) tube inserted for uncontrolled haematemesis, which was unfortunately complicated by malposition of the gastric balloon with resultant oesophageal rupture. The inflated SB tube gastric balloon was visualised within the right hemithorax on chest radiography after the SB tube insertion. Further evaluation of the thorax on computed tomography confirmed the diagnosis of oesophageal rupture associated with right-sided haemopneumothorax. It is crucial for both the referring clinician and reporting radiologist to recognise early the imaging features of an incorrectly positioned SB tube gastric balloon, so as to ensure prompt intervention and a reduction in patient morbidity and mortality.
Adult ; Diagnosis, Differential ; Esophagus ; injuries ; Gastric Balloon ; adverse effects ; Gastrointestinal Hemorrhage ; diagnosis ; etiology ; Humans ; Intubation, Gastrointestinal ; adverse effects ; instrumentation ; Male ; Radiography, Thoracic ; methods ; Rupture ; Tomography, X-Ray Computed ; methods

OBJECTIVE: To evaluate the influence of high-pitch mode (HPM) in dual-source computed tomography (DSCT) on the accuracy of three-dimensional (3D) volumetry for solid pulmonary nodules. MATERIALS AND METHODS: A lung phantom implanted with 45 solid pulmonary nodules (n = 15 for each of 4-mm, 6-mm, and 8-mm in diameter) was scanned twice, first in conventional pitch mode (CPM) and then in HPM using DSCT. The relative percentage volume errors (RPEs) of 3D volumetry were compared between the HPM and CPM. In addition, the intermode volume variability (IVV) of 3D volumetry was calculated. RESULTS: In the measurement of the 6-mm and 8-mm nodules, there was no significant difference in RPE (p > 0.05, respectively) between the CPM and HPM (IVVs of 1.2 +/- 0.9%, and 1.7 +/- 1.5%, respectively). In the measurement of the 4-mm nodules, the mean RPE in the HPM (35.1 +/- 7.4%) was significantly greater (p < 0.01) than that in the CPM (18.4 +/- 5.3%), with an IVV of 13.1 +/- 6.6%. However, the IVVs were in an acceptable range (< 25%), regardless of nodule size. CONCLUSION: The accuracy of 3D volumetry with HPM for solid pulmonary nodule is comparable to that with CPM. However, the use of HPM may adversely affect the accuracy of 3D volumetry for smaller (< 5 mm in diameter) nodule.
Humans ; Imaging, Three-Dimensional/instrumentation/*methods ; Lung/radiography ; Lung Neoplasms/*radiography ; Multiple Pulmonary Nodules/*radiography ; Phantoms, Imaging ; Solitary Pulmonary Nodule/*radiography ; Tomography, X-Ray Computed/instrumentation/*methods

Computed tomography (CT) is widely used in postmortem investigations as an adjunct to the traditional autopsy in forensic medicine. To date, several studies have described postmortem CT findings as being caused by normal postmortem changes. However, on interpretation, postmortem CT findings that are seemingly due to normal postmortem changes initially, may not have been mere postmortem artifacts. In this pictorial essay, we describe the common postmortem CT findings in cases of atraumatic in-hospital death and describe the diagnostic pitfalls of normal postmortem changes that can mimic real pathologic lesions.
Adult ; Aged ; Autopsy/instrumentation/*methods ; Brain/pathology/radiography ; Female ; Forensic Medicine/instrumentation/*methods ; Gastrointestinal Tract/pathology/radiography ; Heart/radiography ; Humans ; Lung/pathology/radiography ; Male ; Middle Aged ; Myocardium/pathology ; Postmortem Changes ; Tomography, X-Ray Computed/*methods

OBJECTIVE: To evaluate the technical feasibility and clinical outcome of percutaneous aspiration embolectomy for embolic occlusion of the superior mesenteric artery (SMA). MATERIALS AND METHODS: Between January 2010 and December 2013, 9 patients with embolic occlusion of the SMA were treated by percutaneous aspiration embolectomy in 2 academic teaching hospitals. The aspiration embolectomy procedure was performed with the 6-Fr and 7-Fr guiding catheter. Thrombolysis was performed with urokinase using a multiple-sidehole infusion catheter. The clinical outcome was investigated retrospectively. RESULTS: Superior mesenteric artery occlusion was initially diagnosed by computed tomography (CT) in all patients, and all patients had no obvious evidence of bowel infarction on CT scan. Percutaneous aspiration embolectomy was primarily performed in 6 patients, and thrombolysis was initially performed in 3 patients. In 3 patients who received primary thrombolysis, percutaneous aspiration was undertaken because the emboli were resistant to urokinase. Complete angiographic success was achieved in 6 patients and partial angiographic success was accomplished in 3 patients. One patient underwent bowel resection. One patient died of whole bowel necrosis and sepsis, and 8 patients survived without complications. CONCLUSION: Percutaneous aspiration embolectomy is a useful tool in recanalization of embolic occlusion of the SMA in select patients.
Adult ; Aged ; Aged, 80 and over ; Angiography/methods ; Embolectomy/*methods ; Embolism/complications/radiography/*surgery ; Female ; Humans ; Male ; Mesenteric Artery, Superior/radiography/*surgery ; Mesenteric Vascular Occlusion/etiology/radiography/*surgery ; Middle Aged ; Retrospective Studies ; Suction/instrumentation/methods ; Thrombolytic Therapy/methods ; Tomography, X-Ray Computed ; Treatment Outcome ; Urokinase-Type Plasminogen Activator/administration & dosage ; Vascular Access Devices

OBJECTIVE: To investigate the accuracy, efficiency and radiation dose of a novel laser navigation system (LNS) compared to those of free-handed punctures on computed tomography (CT). MATERIALS AND METHODS: Sixty punctures were performed using a phantom body to compare accuracy, timely effort, and radiation dose of the conventional free-handed procedure to those of the LNS-guided method. An additional 20 LNS-guided interventions were performed on another phantom to confirm accuracy. Ten patients subsequently underwent LNS-guided punctures. RESULTS: The phantom 1-LNS group showed a target point accuracy of 4.0 +/- 2.7 mm (freehand, 6.3 +/- 3.6 mm; p = 0.008), entrance point accuracy of 0.8 +/- 0.6 mm (freehand, 6.1 +/- 4.7 mm), needle angulation accuracy of 1.3 +/- 0.9degrees (freehand, 3.4 +/- 3.1degrees; p < 0.001), intervention time of 7.03 +/- 5.18 minutes (freehand, 8.38 +/- 4.09 minutes; p = 0.006), and 4.2 +/- 3.6 CT images (freehand, 7.9 +/- 5.1; p < 0.001). These results show significant improvement in 60 punctures compared to freehand. The phantom 2-LNS group showed a target point accuracy of 3.6 +/- 2.5 mm, entrance point accuracy of 1.4 +/- 2.0 mm, needle angulation accuracy of 1.0 +/- 1.2degrees, intervention time of 1.44 +/- 0.22 minutes, and 3.4 +/- 1.7 CT images. The LNS group achieved target point accuracy of 5.0 +/- 1.2 mm, entrance point accuracy of 2.0 +/- 1.5 mm, needle angulation accuracy of 1.5 +/- 0.3degrees, intervention time of 12.08 +/- 3.07 minutes, and used 5.7 +/- 1.6 CT-images for the first experience with patients. CONCLUSION: Laser navigation system improved accuracy, duration of intervention, and radiation dose of CT-guided interventions.
Adult ; Female ; Humans ; Image-Guided Biopsy/methods ; *Lasers ; Male ; Middle Aged ; Needles ; Phantoms, Imaging ; Punctures/*methods ; Tomography, X-Ray Computed/*instrumentation/*methods

The development of cardiac CT has provided a non-invasive alternative to echocardiography, exercise electrocardiogram, and invasive angiography and cardiac CT continues to develop at an exponential speed even now. The appropriate use of cardiac CT may lead to improvements in the medical performances of physicians and can reduce medical costs which eventually contribute to better public health. However, until now, there has been no guideline regarding the appropriate use of cardiac CT in Korea. We intend to provide guidelines for the appropriate use of cardiac CT in heart diseases based on scientific data. The purpose of this guideline is to assist clinicians and other health professionals in the use of cardiac CT for diagnosis and treatment of heart diseases, especially in patients at high risk or suspected of heart disease.
Chest Pain/*diagnosis/radiography ; Exercise ; Heart/radiography ; Heart Diseases/diagnosis/*radiography ; Humans ; Republic of Korea ; Tomography, X-Ray Computed/instrumentation/*methods/*standards