Abstract
This study investigated the utility of quantifying iodine concentration (IC) in perigastric adipose tissue, using dual-energy computed tomography (DECT), for the detection of T4a-stage gastric cancer. Fifty-four patients with gastric cancer were enrolled at the Fourth Hospital of Hebei Medical University between January and June 2013. Patients were imaged preoperatively with conventional computed tomography (CT) scans and DECT, and the IC in perigastric fat adjacent to the tumor calculated from arterial phase (AP) and portal venous phase (PVP) images. The patients subsequently received surgical treatment (gastrectomy), and histologic analysis of resected specimens was used as a ‘gold standard’ reference for cancer staging. Receiver operating characteristic (ROC) curve analysis was employed to assess the utility of DECT for identifying T4a-stage gastric cancer, with optimal IC thresholds determined from the area under the ROC curve (AUC). Postoperative histology revealed that 32 patients had serosal invasion (group A), and 22 did not (group B). The accuracy of conventional CT for distinguishing stage T4 from non-T4 stages was 68.5% (37/54). IC was significantly higher in group A than in group B (AP: 0.60±0.34 vs. 0.09±0.19 mg/mL, p<0.001; PVP: 0.83±0.41 vs. 0.27±0.21 mg/mL, p<0.001). The sensitivity, specificity and AUC for detecting serosal invasion were 77.1%, 79.2% and 0.89 at an IC threshold of 0.25 mg/mL for AP images; and 80.0%, 79.2% and 0.90 at an IC threshold of 0.45 mg/mL for PVP images. These results indicated that Iodine quantification in perigastric fat using DECT is an accurate method for detecting serosal invasion by gastric cancer.
Highlights
Gastric cancer is one of the most frequently diagnosed cancers, and is a leading cause of cancer-related deaths worldwide [1,2,3]
Neoadjuvant chemotherapy is strongly recommended for patients with T4 staging and lymph node metastasis, and may be beneficial to those with T4a stage in down grading the tumor prior to resection allowing in some cases curative resection [10]
Neoadjuvant chemotherapy is recommended for stage T4 tumors in our hospital so those patients who were included with confirmed T4 stage tumors had opted according to their own judgement to receive early surgery. 5 patients with fat layers that were too thin for measurement by computed tomography (CT), considered to have technique failure, were included in the calculation for sensitivity and specificity but not in the Receiver operating characteristic (ROC) curve analysis
Summary
Gastric cancer is one of the most frequently diagnosed cancers, and is a leading cause of cancer-related deaths worldwide [1,2,3]. The preoperative staging of gastric cancer is widely recognized as an invaluable aid for determining the optimal therapy and evaluating tumor resectability and patient prognosis [4,5,6]. Differentiating T4a-stage gastric cancer from T3 or earlier stages is important with regard to preoperative selection of appropriate treatment strategies, including the requirement for multi-organ surgery [7,8,9]. Multi-detector computed tomography (MDCT) is often chosen as the modality for preoperative staging, and has been shown to have an overall accuracy that approaches 90% [5,7,9]. As MDCT does not show complete agreement with postoperative staging by histologic analysis of surgically resected specimens new approaches are needed to improve the sensitivity, specificity and accuracy of imaging modalities for the preoperative staging of gastric cancer
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