Lung cancer is the leading cause of cancer-related deaths worldwide. Radiation pneumonitis is a major complication in lung cancer radiotherapy. Four-dimensional computed tomography (4DCT) imaging provides dynamic ventilation information, which is valuable for lung function assessment and radiation pneumonitis prevention. Many methods have been developed to calculate lung ventilation from 4DCT, but a systematic comparison is lacking. Prediction of radiation pneumonitis using 4DCT-based ventilation is still in an early stage, and no comprehensive review exists. This paper presented the first systematic comparison of functional lung ventilation algorithms based on 4DCT over the past 15 years, highlighting their clinical value and limitations. It then reviewed multimodal approaches combining 4DCT ventilation imaging, dose metrics, and clinical data for radiation pneumonitis prediction. Finally, it summarized current research and future directions of 4DCT in lung cancer radiotherapy, offering insights for clinical practice and further studies.
Humans ; Lung Neoplasms/diagnostic imaging* ; Four-Dimensional Computed Tomography/methods* ; Radiation Pneumonitis/etiology* ; Algorithms ; Lung/radiation effects* ; Pulmonary Ventilation

Objective To evaluate the application value of four-dimensional CT(4D-CT)in the preoperative localization of primary hyperparathyroidism(PHPT). Methods A retrospective analysis was conducted on the clinical data and parathyroid 4D-CT images of 63 patients who underwent PHPT surgery at Peking Union Medical College Hospital between April 2020 and April 2023.Based on the clinical experience of the hospital's surgeons,parathyroid lesions were categorized into six anatomical regions:around the upper pole of the thyroid,posterior to the mid-thyroid,posterior to the lower pole of the thyroid and the tracheoesophageal groove,below the lower pole of the thyroid and the suprasternal fossa,retrosternal anterior mediastinum,and other rare locations.All images were independently analyzed by two experienced radiologists,with discrepancies resolved through discussion led by a senior radiologist.Using pathological results as the gold standard,the accuracy,sensitivity,specificity,positive predictive value(PPV),negative predictive value(NPV),Youden index,positive likelihood ratio(PLR),and negative likelihood ratio(NLR)of preoperative 4D-CT in diagnosing PHPT were calculated. Results There were no statistically significant differences between preoperative 4D-CT and surgical localization in the following regions:around the upper pole of the thyroid(χ²=0.500,P=0.480),posterior to the mid-thyroid(χ²<0.001,P>0.999),posterior to the lower pole of the thyroid and the tracheoesophageal groove(χ²=0.571,P=0.450),below the lower pole of the thyroid and the suprasternal fossa(χ²<0.001,P>0.999),retrosternal anterior mediastinum(χ²<0.001,P>0.999),and other rare locations(χ²<0.001,P>0.999).The preoperative 4D-CT diagnosis of PHPT lesions demonstrated a sensitivity of 82.09%,specificity of 97.43%,PPV of 87.30%,NPV of 96.19%,accuracy of 94.71%,Youden index of 79.52%,PLR of 31.94,and NLR of 0.18. Conclusion Parathyroid 4D-CT demonstrates good diagnostic efficacy in the preoperative localization of PHPT.
Humans ; Hyperparathyroidism, Primary/surgery* ; Retrospective Studies ; Four-Dimensional Computed Tomography ; Male ; Female ; Middle Aged ; Adult ; Aged ; Parathyroid Glands/diagnostic imaging* ; Preoperative Period

BACKGROUND AND OBJECTIVES: Decreased left atrial appendage (LAA) emptying velocity in transesophageal echocardiography (TEE) is related with higher incidence of thrombus and increased risk of stroke. Patients with valve disease are at higher risk of thrombus formation before and after surgery. The aim of this study was to investigate the role of 4-dimensional cardiac computed tomography (4DCT) to predict the risk of thrombus formation. METHODS: Between March 2010 to March 2015, total of 62 patients (mean 60±15 years old, male: 53.2%) who underwent 4DCT and TEE for cardiac valve evaluation before surgery were retrospectively included in the current study. Fractional area change in TEE view and emptying velocity at left atrial appendage in TEE view (VeTEE) were measured. Ejection fraction (EF) of left atrial appendage in computed tomography (EFCT) was calculated by 4DCT with full volume analysis. The best cut-off value of EFCT predicting presence of spontaneous echo contrast (SEC) or thrombus was evaluated, and correlation between the parameters were also estimated. RESULTS: SEC or thrombus was observed in 45.2%. EFCT and VeTEE were significantly correlated (r=0.452, p < 0.001). However, fractional area change measured by TEE showed no correlation with VeTEE (r=0.085, p=0.512). EFCT < 37.5% best predicted SEC or thrombus in the patients with valve disease who underwent 4DCT and TEE (area under the curve, 0.654; p=0.038). CONCLUSIONS: In the patients who underwent 4DCT for cardiac valve evaluation before surgery, EFCT by volume analysis might have additional role to evaluate LAA function and estimate the risk of thrombus.
Atrial Appendage ; Echocardiography, Transesophageal ; Four-Dimensional Computed Tomography ; Heart Valve Diseases ; Heart Valves ; Humans ; Incidence ; Male ; Retrospective Studies ; Stroke ; Thrombosis

In pediatric thoracic CT, respiratory motion is generally treated as a motion artifact degrading the image quality. Conversely, respiratory motion in the thorax can be used to answer important clinical questions, that cannot be assessed adequately via conventional static thoracic CT, by utilizing four-dimensional (4D) CT. However, clinical experiences of 4D thoracic CT are quite limited. In order to use 4D thoracic CT properly, imagers should understand imaging techniques, radiation dose optimization methods, and normal as well as typical abnormal imaging appearances. In this article, the imaging techniques of pediatric thoracic 4D CT are reviewed with an emphasis on radiation dose. In addition, several clinical applications of pediatric 4D thoracic CT are addressed in various thoracic functional abnormalities, including upper airway obstruction, tracheobronchomalacia, pulmonary air trapping, abnormal diaphragmatic motion, and tumor invasion. One may further explore the clinical usefulness of 4D thoracic CT in free-breathing children, which can enrich one's clinical practice.
Airway Obstruction ; Artifacts ; Child* ; Four-Dimensional Computed Tomography ; Humans ; Thorax ; Tomography, X-Ray Computed ; Tracheobronchomalacia

Four-dimensional cone beam CT (4D-CBCT) imaging can provide accurate location information of real-time breathing for imaging-guided radiotherapy. How to improve the accuracy of 4D-CBCT reconstruction image is a hot topic in current studies. PICCS algorithm performs remarkably in all 4D-CBCT reconstruction algorithms based on CS theory. The improved PICCS algorithm proposed in this paper improves the prior image on the basis of the traditional PICCS algorithm. According to the location information of each phase, the corresponding prior image is constructed, which completely eliminates the motion blur of the reconstructed image caused by the mismatch of the projection data. Meanwhile, the data fidelity model of the proposed method is consistent with the traditional PICCS algorithm. The experimental results showed that the reconstructed image using the proposed method had a clearer organization boundary compared with that of images reconstructed using the traditional PICCS algorithm. This proposed method significantly reduced the motion artifact and improved the image resolution.
Algorithms ; Cone-Beam Computed Tomography ; methods ; Four-Dimensional Computed Tomography ; Humans ; Image Processing, Computer-Assisted ; Organ Motion ; Radiographic Image Enhancement ; instrumentation ; methods ; Respiration

OBJECTIVE: To evaluate the technical feasibility of four-dimensional (4D) CT for the functional evaluation of the pediatric diaphragm. MATERIALS AND METHODS: In 22 consecutive children (median age 3.5 months, age range 3 days–3 years), 4D CT was performed to assess diaphragm motion. Diaphragm abnormalities were qualitatively evaluated and diaphragm motion was quantitatively measured on 4D CT. Lung density changes between peak inspiration and expiration were measured in the basal lung parenchyma. The diaphragm motions and lung density changes measured on 4D CT were compared between various diaphragm conditions. In 11 of the 22 children, chest sonography was available for comparison. RESULTS: Four-dimensional CT demonstrated normal diaphragm (n = 8), paralysis (n = 10), eventration (n = 3), and diffusely decreased motion (n = 1). Chest sonography demonstrated normal diaphragm (n = 2), paralysis (n = 6), eventration (n = 2), and right pleural effusion (n = 1). The sonographic findings were concordant with the 4D CT findings in 90.9% (10/11) of the patients. In diaphragm paralysis, the affected diaphragm motion was significantly decreased compared with the contralateral normal diaphragm motion (−1.1 ± 2.2 mm vs. 7.6 ± 3.8 mm, p = 0.005). The normal diaphragms showed significantly greater motion than the paralyzed diaphragms (4.5 ± 2.1 mm vs. −1.1 ± 2.2 mm, p < 0.0001), while the normal diaphragm motion was significantly smaller than the motion of the contralateral normal diaphragm in paralysis (4.5 ± 2.1 mm vs. 7.6 ± 3.8 mm, p = 0.01). Basal lung density change of the affected side was significantly smaller than that of the contralateral side in diaphragm paralysis (89 ± 73 Hounsfield units [HU] vs. 180 ± 71 HU, p = 0.03), while no significant differences were found between the normal diaphragms and the paralyzed diaphragms (136 ± 66 HU vs. 89 ± 73 HU, p = 0.1) or between the normal diaphragms and the contralateral normal diaphragms in paralysis (136 ± 66 HU vs. 180 ± 71 HU, p = 0.1). CONCLUSION: The functional evaluation of the pediatric diaphragm is feasible with 4D CT in select children.
Child ; Diaphragm ; Diaphragmatic Eventration ; Four-Dimensional Computed Tomography ; Humans ; Lung ; Paralysis ; Pleural Effusion ; Thorax ; Ultrasonography

Patients with locally advanced lung cancer and very limited pulmonary function (forced expiratory volume in 1 second [FEV1] ≤ 1 L) have dismal prognosis and undergo palliative treatment or best supportive care. We describe two cases of locally advanced node-positive non-small cell lung cancer (NSCLC) patients with very limited lung function treated with induction chemotherapy and moderate hypofractionated image-guided radiotherapy (Hypo-IGRT). Hypo-IGRT was delivered to a total dose of 45 Gy to the primary tumor and involved lymph nodes. Planning was based on positron emission tomography-computed tomography (PET/ CT) and four-dimensional computed tomography (4D-CT). Internal target volume (ITV) was defined as the overlap of gross tumor volume delineated on 10 phases of 4D-CT. ITV to planning target volume margin was 5 mm in all directions. Both patients showed good clinical and radiological response. No relevant toxicity was documented. Hypo-IGRT is feasible treatment option in locally advanced node-positive NSCLC patients with very limited lung function (FEV1 ≤ 1 L).
Carcinoma, Non-Small-Cell Lung* ; Electrons ; Four-Dimensional Computed Tomography ; Humans ; Induction Chemotherapy ; Lung Neoplasms ; Lung* ; Lymph Nodes ; Palliative Care ; Prognosis ; Radiotherapy* ; Radiotherapy, Image-Guided ; Tumor Burden

PURPOSE: To see the gross tumor volume (GTV) dependency according to the phase selection and reconstruction methods, we measured and analyzed the changes of tumor volume and motion at each phase in 20 cases with lung cancer patients who underwent image-guided radiotherapy. MATERIALS AND METHODS: We retrospectively analyzed four-dimensional computed tomography (4D-CT) images in 20 cases of 19 patients who underwent image-guided radiotherapy. The 4D-CT images were reconstructed by the maximum intensity projection (MIP) and the minimum intensity projection (Min-IP) method after sorting phase as 40%–60%, 30%–70%, and 0%–90%. We analyzed the relationship between the range of motion and the change of GTV according to the reconstruction method. RESULTS: The motion ranges of GTVs are statistically significant only for the tumor motion in craniocaudal direction. The discrepancies of GTV volume and motion between MIP and Min-IP increased rapidly as the wider ranges of duty cycles are selected. CONCLUSION: As narrow as possible duty cycle such as 40%–60% and MIP reconstruction was suitable for lung cancer if the respiration was stable. Selecting the reconstruction methods and duty cycle is important for small size and for large motion range tumors.
Four-Dimensional Computed Tomography* ; Humans ; Lung Neoplasms* ; Lung* ; Methods* ; Radiotherapy, Image-Guided ; Range of Motion, Articular ; Respiration ; Retrospective Studies ; Tumor Burden*

PURPOSE: To see the gross tumor volume (GTV) dependency according to the phase selection and reconstruction methods, we measured and analyzed the changes of tumor volume and motion at each phase in 20 cases with lung cancer patients who underwent image-guided radiotherapy. MATERIALS AND METHODS: We retrospectively analyzed four-dimensional computed tomography (4D-CT) images in 20 cases of 19 patients who underwent image-guided radiotherapy. The 4D-CT images were reconstructed by the maximum intensity projection (MIP) and the minimum intensity projection (Min-IP) method after sorting phase as 40%–60%, 30%–70%, and 0%–90%. We analyzed the relationship between the range of motion and the change of GTV according to the reconstruction method. RESULTS: The motion ranges of GTVs are statistically significant only for the tumor motion in craniocaudal direction. The discrepancies of GTV volume and motion between MIP and Min-IP increased rapidly as the wider ranges of duty cycles are selected. CONCLUSION: As narrow as possible duty cycle such as 40%–60% and MIP reconstruction was suitable for lung cancer if the respiration was stable. Selecting the reconstruction methods and duty cycle is important for small size and for large motion range tumors.
Four-Dimensional Computed Tomography* ; Humans ; Lung Neoplasms* ; Lung* ; Methods* ; Radiotherapy, Image-Guided ; Range of Motion, Articular ; Respiration ; Retrospective Studies ; Tumor Burden*

INTRODUCTIONA paradigm shift appears to have occurred worldwide in surgery for primary hyperparathyroidism with the advent of sensitive preoperative imaging techniques. Preoperative imaging for parathyroid adenoma localisation was not found to be useful in a study conducted in Singapore in the 1990s. This study aimed to explore what the change has been in preoperative localisation tools compared to the previous study and if the ability of these tools to correctly localise pathologic parathyroid glands has improved.

MATERIALS AND METHODSA retrospective review of patients who had surgery for primary hyperparathyroidism at our institution during the period 2005 to 2014 was carried out. Individuals with positive, as opposed to those with negative preoperative imaging, were compared with regard to whether they underwent limited focal or bilateral neck exploration. Length of hospital stay (LOHS) was also compared between patients who underwent limited versus bilateral exploration.

RESULTSFifty-eight patients who had preoperative imaging and surgery were evaluated. True positive rates of sestamibi, ultrasound and 4-dimensional (4D) computed tomography (CT) scans were 63.8%, 72.4% and 90%, respectively. Eighty percent of patients who had positive localisation had limited exploration. LOHS was 2.8 days (1.6, 4.8) and 4.3 days (2.1, 9.0) for limited and bilateral exploration respectively, P = 0.011.

CONCLUSIONOur study highlights the marked change in the surgical landscape for primary hyperparathyroidism in the last 2 decades in Singapore. Improved preoperative localisation has resulted in a swing from predominantly bilateral, to limited exploration in almost all cases of primary hyperparathyroidism due to solitary adenoma. LOHS was significantly shorter in patients who had limited as compared to those who had bilateral exploration.

Adenoma ; diagnostic imaging ; surgery ; Four-Dimensional Computed Tomography ; Humans ; Hyperparathyroidism, Primary ; diagnostic imaging ; surgery ; Length of Stay ; Parathyroid Neoplasms ; diagnostic imaging ; surgery ; Parathyroidectomy ; Practice Patterns, Physicians' ; Radionuclide Imaging ; Radiopharmaceuticals ; Retrospective Studies ; Sensitivity and Specificity ; Singapore ; Technetium Tc 99m Sestamibi ; Ultrasonography