Radiology Innovation

The role of baseline mesorectal fascia status and its change after neoadjuvant therapy in predicting prognosis in locally advanced rectal cancer

Xueping Li — 2022-06-30

Objective: To analyze the role of baseline mesorectal fascia (MRF) status and the correlation between MRF changes and prognosis after neoadjuvant therapy in patients with locally advanced rectal cancer.

Methods: Totally 321 patients with locally advanced rectal cancer were retrospectively analyzed from January 2014 to December 2016 in Peking University Cancer Hospital. All Patients underwent surgery after neoadjuvant radiotherapy and chemotherapy, and were followed up regularly after surgery. The MRF status, extramural vascular invasion (EMVI) status, tumor location, tumor stage and lymph node status were evaluated on baseline MRI. For patients with positive baseline MRF, preoperative MRF status was also evaluated. Chi‑square test or independent t test were used to compare the characteristics between MRF positive and negative patients. Kaplan‑Meier curve, log‑rank test and multivariate Cox regression were used to analyze the correlation between imaging features and prognosis.

Results: In all of the 321 subjects, 193 (60.1%) had positive baseline MRF, 54 (28.0%) of the 193 patients had negative MRF after neoadjuvant therapy, and 139 (72.0%) of them still had positive MRF preoperatively. The postoperative pathological T and N stages were significantly higher in patients with positive baseline MRF than those with negative MRF, and the proportion of patients achieving complete pathological response was significantly lower than those with negative MRF (All P < 0.05). The postoperative pathological T and N stages of patients with MRF negative conversion were significantly lower than those without MRF negative conversion. In patients with negative baseline MRF and patients with negative MRF conversion after neoadjuvant therapy, the proportion of positive MRI EMVI was significantly lower (All P < 0.05). Univariate survival analysis showed that overall survival and metastasis free survival were poorer in patients with positive MRF at baseline, with a hazard ratio of 3.33 and 1.69, respectively. There was no significant correlation between negative MRF conversion after neoadjuvant therapy and overall survival, metastasis free survival and recurrence free survival. Multivariate Cox analysis showed that baseline MRF and EMVI status were independent factors for overall survival and metastasis free survival, with a risk ratio of 2.15 and 3.35 for overall survival, 1.13 and 2.74 for metastasis free survival, respectively.

Conclusions: Baseline MRF status is one of the independent prognostic predictors in locally advanced rectal cancer patients with neoadjuvant therapy. However, the role of the change in MRF status after neoadjuvant therapy is uncertain for predicting prognosis.

Study on intraoperative ultrasonographic features of small lung cancer lesions with ground glass nodules on computerized tomography

Zhe Chen — 2022-06-30

Objective: This study intends to compare the preoperative high resolution computed tomography (HRCT) and intraoperative ultrasonic (partial contrast-enhanced ultrasonic) images of a group of small lung cancer lesions with ground glass nodules (GGN) on computerized tomography (CT), and to explore the imaging features of small lung cancer lesions with GGN and the sonographic findings of some GGN contrast-enhanced ultrasonic (CEUS).

Methods: 41 patients with CT with ground glass nodules confirmed by pathology in Cancer Hospital of China Medical University from January 2019 to December 2021 were collected. Among them, 15 patients were examined by intraoperative contrast-enhanced ultrasonic. All patients were examined by high resolution computed tomography (HRCT) before operation and intraoperative ultrasonic during video-assisted thoracoscopic surgery (VATS). SPSS 22.0 software was adopted for data processing. If the data were in accordance with normal distribution, t-test was adopted between groups, and Fisher exact probability test was adopted for univariate analysis. P < 0.05 suggested that the difference was statistically significant.

Results: (1) There was significant difference between pure ground glass nodule (pGGN) and partial ground glass nodule (mGGN) in nodule diameter, shape, marginal spiculation sign, lobulation sign, pleural traction or indentation sign. There was significant difference in the edge of nodules and the short diameter of lesions between pGGN and mGGN (P < 0.05). (2) There was significant difference in nodule size between preoperative HRCT and intraoperative ultrasonic (P < 0.05). There was a significant difference in the size of GGN between preoperative HRCT and intraoperative ultrasonic (P < 0.05). There was significant difference in the time to start enhancement (TE) and the time to peak (TTP) between GGN contrast-enhanced ultrasonic and collapsed lung tissue (P < 0.05). Among the 15 cases of CEUS, 13 cases of GGN showed “slow in and fast out” mode compared with collapsed lung tissue, and 2 cases of GGN showed “fast in and fast out” mode compared with collapsed lung tissue.

Conclusion: (1) In VATS operation of GGN lung cancer, the lesions observed by ultrasonic can be distinguished according to the shape and edge characteristics of the lesions on CT before operation. (2) In terms of intraoperative ultrasonographic features of VATS, mGGN has a longer short diameter of lesions than pGGN, and the edge of lesions is more lobulated. (3) Contrast-enhanced ultrasonic mostly showed low enhancement in GGN micro-lung cancer, and its contrast-enhanced mode was “slow in and fast out”. The use of this feature is beneficial to the confirmation of micro-lung cancer nodules during operation.

Locally advanced rectal cancer: an MRI radiomics study on lymph node re-evaluation after neoadjuvant chemoradiotherapy

Xiaoyan Zhang — 2022-06-30

Objective: To develop and validate one optimal MR radiomics model for lymph node (LN) re-evaluation of locally advanced rectal cancer (LARC) after neoadjuvant chemoradiotherapy (NCRT).

Methods: Four hundred and seven patients with clinicopathologically confirmed LARC in Beijing Cancer Hospital were included in this study from July 2010 to June 2015. All patients received NCRT before surgery, and underwent T2WI and DWI before and after NCRT. These patients were chronologically divided in the primary cohort (300 patients) and independent validation cohort (107 patients). The predicting model was trained and validated using postoperative pathological findings as truth values. By using radiomics method, we extracted the features of the tumor and the largest LN before and after neoadjuvant therapy, combined different features of the tumor and /or the largest LN before and/or after neoadjuvant therapy, and constructed 4 different prediction models, compared the performance of four predicting models. The optimal conducted to determine the clinical usefulness of the radiomics nomograms by quantifying the net benefits at different threshold probabilities in the validation dataset.

Results: In the primary cohort, the radiomics signatures from 4 models provided an AUC of 0.637, 0.709, 0.753, 0.835, respectively in LN re-evaluation after chemoradiotherapy. The diagnostic efficacy of model 4 was much better than that of 1, 2 and 3 model. In the validation cohort, the radiomics signatures provided an AUC of 0.795 for LN re-evaluation after chemoradiotherapy. The sensitivity, specificity, positive predictive value, negative predictive value were 0.813, 0.693, 0.531, 0.897, respectively (95% CI: 0.694 to 0.896, 0.647 to 0.911, 0.582 to 0.786, 0.361 to 0.621, 0.792 to 0.952). While the probability of predicting N+ ranges from 17% to 80%, using the proposed radiomics model to predict N+ shows a greater advantage than either the scheme in which all patients were assumed to N+ or the scheme in which all patients are N–. Decision curve analysis demonstrated that the radiomics nomograms were clinically useful.

Conclusion: With a systematic analysis and comparison of both pre-and post-NCRT MRI data, we constructed an optimal individualized LN re-evaluation model based on MR radiomics, combing primary tumor and the largest LN features, compared with other models (only with pre/post tumor or pre/post largest LN features).

Adjustment of the underestimation of coronary artery calcification scoring and risk reclassification in low-dose coronary computed tomography angiography with Knowledge-based Iterative Model Reconstruction

Shaowei Ma — 2022-06-30

Background: Knowledge-based iterative model reconstruction (IMR) can reduce radiation exposure, but trend to underestimate coronary artery calcification score (CACS) on computed tomography. We aimed to adjust the impact of low-dose IMR on CAC scoring and risk reclassification.

Methods: From June 2016 to July 2018, two groups of patients (N = 250 and N = 346) who underwent routine-dose (120kV, 50mA) CAC scan with filtered back projection (FBP) reconstruction were enrolled as training and testing group respectively. A low-dose (120kV, 20mA) scan with IMR reconstruction was performed at the same time. Agatston scores were calculated semi-automatically on the routine-dose FBP and low-dose IMR images. In the training group, a mathematical relationship between the CAC scores obtained from FBP and IMR was modeled by weighted least square method. In the testing group, adjusted IMR (ad-IMR) scores were calculated using the equation from the training group. Differences between ad-IMR and FBP scores, and consistency rates of risk categories by IMR/ad-IMR to FBP scores were analyzed.

Results: In the training group, CAC were underestimated by 26.0% (P < 0.0001) with low-dose IMR, the adjustment equation was Y = 17.45 + 1.14X (Y: FBP, X: IMR R²= 0.96). There was no difference between ad-IMR and FBP scores in testing group. Furthermore, the consistency rate of risk categories was significantly improved by ad-IMR scores (from 74.0% to 85.3%, P < 0.001), greater improvement was observed in patients with FBP score > 10 (91.6%).

Conclusion: The underestimation of CACS by low-dose scan with IMR reconstruction could be adjusted by mathematical adjustment. The impact on risk reclassification can be improved thereby facilitating further dose reductions.

Launch A Voyage of Academic-Discovery in Radiology Innovation

Yingshi Sun — 2022-06-30