Early-stage esophageal cancer patients usually show no obvious symptoms, by the time they are diagnosed, most are already in the late stage, leading to a large variation in prognosis (1). Early-stage esophageal cancer, if treated with radical resection, is expected to achieve long-term survival. In contrast, for some advanced cases, surgery may be futile or even harmful, increasing patient trauma and hastening death (2). Therefore, how to diagnose esophageal cancer early and accurately stage it preoperatively has become a major and difficult task in the field of esophageal surgery. Accurate preoperative staging helps surgeons select appropriate treatment strategies (3).

To allow early-stage esophageal cancer patients to undergo radical surgical treatment, and to avoid unnecessary or palliative surgery and chemoradiotherapy in late-stage patients, many imaging methods have been applied in clinical diagnosis of esophageal cancer, such as CT (computed tomography), MRI (magnetic resonance imaging), EUS (endoscopic ultrasonography), PET (positron emission tomography), thoracoscopy, and laparoscopy (4). Researchers have been conducting studies on the accuracy of these methods in TNM staging of esophageal cancer, but there is still no consensus. Among these, CT and MRI are the most widely used (5). This study compares preoperative CT and MRI findings with intraoperative and postoperative pathological results, identifying their respective advantages and limitations, in order to guide clinical practice.

From January 2014 to December 2024, a total of 1,209 patients with esophageal cancer underwent preoperative TNM staging via CT (868 cases) or MRI (341 cases). There were no differences in gender, age, BMI, tumor height and pathological types between the two groups (Table 1).

After the diagnosis of esophageal cancer, it is very important for clinical surgeons to accurately determine the TNM stage of the tumor to choose the individualized treatment plan (7). In recent years, with the popularity of CT and MRI, it has brought many benefits for esophageal surgeons and patients to choose the appropriate treatment mode, but its accuracy in preoperative TN staging of esophageal cancer has been controversial (8).

It can be seen from the results of this study that there is no difference between CT and MRI in preoperative TN staging of esophageal cancer (with postoperative gross pathological results as the gold standard) in terms of sensitivity, specificity and accuracy (x test, p > 0.05). The advantage of CT is that the imaging technology is simple, the parameters are less, and it is easy to be grasped by clinicians. The price is relatively low. Enhanced CT scan can also show the relationship between the mass and the large blood vessels of the heart, making up for the lack of traditional X-ray examination, and the vast majority of cases can be diagnosed with X-ray and CT results. However, for some special cases, conventional CT scan has limitations, so MRI examination is necessary. MRI has the advantages of being multi-directional (axial, sagittal, coronal or even oblique), showing tumor components, the relationship between tumor and blood vessels, and the blood vessels within the tumor (9). The disadvantages are that MRI has many imaging parameters, is susceptible to interference by external factors (breathing, heartbeat), and is expensive (10).

A large number of literatures have reported that the accuracy of CT and MRI for preoperative T staging of esophageal cancer ranges from 45 to 73% (11). The results of this study showed that for T1 and T2 tumors, the diagnostic coincidence rate of CT and MRI was not high, especially when T1 tumors were confined to the esophageal mucosa or submucosa, (12) the tumors may only cause changes in the local motor function of the esophagus without changes in the thickness of the esophageal wall, while CT and MRI could only perform static imaging of the esophagus, but could not perform dynamic observation. Therefore, there is a high error rate (13). The low accuracy for T1/T2 staging may due to the atypical imaging features of early-stage lesions. Quint et al. (14) proposed that the normal wall thickness of the esophagus was 3 mm, the anteroposterior diameter was 14 mm, and the left and right diameter was 18 mm when the esophagus collapsed. At present, most domestic and foreign scholars still determine the depth of tumor invasion by observing the thickness of the esophageal wall according to the standard, which is obviously unable to keep up with the development of modern science and technology. How to improve the diagnostic technology of CT and MRI, determine more accurate diagnostic criteria of CT and MRI for esophageal cancer, and achieve early detection of esophageal cancer and screen the depth of tumor invasion still needs to be further discussed by radiologists. Of course, this is one of the main reasons for the current limitations on CT and MRI as alternatives to esophageal barium meal and endoscopy. EUS examination is recommended for patients with suspected early esophageal cancer to improve the accuracy of preoperative staging (15). In the future, we will further combine the EUS with MRI to improve the accuracy.

Although neither CT nor MRI can accurately distinguish each layer of the esophagus and judge the depth of tumor invasion, when esophageal cancer develops to the T3 and T4 stages, CT and MRI can not only show the subtle difference in the density of the tumor and its surrounding tissues, but also display the tumor in multiple directions and carefully distinguish its degree of external invasion in spatial orientation (16). In particular, the accuracy of T4 esophageal cancer was especially high (the T coincidence rate of CT and MRI diagnosis in this group was as high as 92 and 100%, respectively). In addition, CT and MRI can accurately determine whether esophageal cancer has invaded adjacent organs (trachea, bronchus, aorta, pericardium, etc.) and the extent of invasion. Since results demonstrated similar accuracy of CT and MRI, we recommend CT scan for initial screening for its economical and quick characteristic, and MRI for suspected T4 or complex anatomical sites, such as aortic invasion. If cases of suspected T4 stage located at regions with limited medical resources, CT can be the alternative for diagnosis.

CT and MRI have incomparable advantages over traditional X-ray in N staging of esophageal cancer. It is generally believed that pathological enlargement of thoracic lymph nodes >1 cm, subclavian lymph nodes > 0.6 cm, and abdominal lymph nodes > 0.8 cm are pathological enlargement. Due to the high resolution of CT and MRI, the diagnosis rate of mediastinal and abdominal enlarged lymph nodes is relatively high (specificity, sensitivity and diagnostic coincidence rate are >80%), which can provide clinical reference. However, CT and MRI still have high false negative and false positive results. In clinical practice, enlarged lymph nodes are not metastatic lymph nodes, while metastatic lymph nodes are not enlarged. Previous literature reports also confirmed the existence of high false negative and false positive rates in CT and MRI. Therefore, there is still a serious shortage in judging the N stage of esophageal cancer from the size of lymph node findings on CT and MRI alone. The development of tumorophilic contrast imaging is expected to further improve the accuracy of CT and MRI in preoperative TNM staging of esophageal cancer. However, we did not compare the equipment heterogeneity across hospitals. In the future, we will promote the results of this research to other medical centers and conduct a multi-centered prospective study.