Added value of spectral parameters in diagnosing metastatic lymph nodes of pT1-2 rectal cancer

Spectral CT in the evaluation of perineural invasion status in rectal cancer

PURPOSE

To investigate whether preoperative spectral CT quantitative parameters can assess perineural invasion (PNI) status in rectal cancer.

METHODS

Sixty-two patients diagnosed with rectal cancer who underwent preoperative spectral CT were retrospectively enrolled and divided into positive and negative PNI groups according to histopathologic results. The CT attenuation value (HU) of virtual monochromatic images (40-70 keV), spectral curve slope (K(HU)), effective atomic number (Zeff), and iodine concentration (IC) from spectral CT were compared between these two groups using t test or rank sum test. A nomogram was established by incorporating the independent predictors to assess the overall diagnostic efficacy. The area under the ROC curves (AUCs) were compared using the DeLong test.

RESULTS

The preoperative spectral CT parameters (40-70 keV attenuation, K(HU), Zeff, and IC) were significantly higher in the PNI-positive group compared to the PNI-negative group (all p < 0.05). The highest predictive efficiency of PNI was observed at 40 keV attenuation, with an area under the curve (AUC), sensitivity, specificity, and accuracy of 0.847, 81.8%, 72.5%, and 75.8%, respectively. Binary logistic regression demonstrated that the clinical feature (cN stage) and 40 keV attenuation were independent predictors of PNI status. The nomogram incorporating these two predictors (cN stage and 40 keV attenuation) exhibited the best evaluation efficacy, with an AUC, sensitivity, specificity, and accuracy of 0.885, 86.4%, 77.5%, and 80.6%.

CONCLUSION

Spectral CT quantitative parameters proved valuable in the preoperative assessment of PNI status in rectal cancer patients. The combination of spectral CT parameters and clinical features could further enhance the diagnostic efficiency.

Dual-Energy Computed Tomography in Urological Diseases: A Narrative Review

Dual-Energy computed tomography (DECT) with its various advanced techniques, including Virtual Non-Contrast (VNC), effective atomic number (Z-eff) calculation, Z-maps, Iodine Density Index (IDI), and so on, holds great promise in the diagnosis and management of urogenital tumours. In this narrative review, we analyze the current status of knowledge of this technology to provide better lesion characterization, improve the staging accuracy, and give more precise treatment response assessments in relation to urological tumours.

Impact of neoadjuvant therapy on nodal harvest in clinical stage III rectal cancer: Establishing optimum cut-offs by disease response

INTRODUCTION

A minimum lymph node harvest (LNH) of 12 is the current standard for appropriate nodal staging in resectable rectal cancer. However, the rise of neoadjuvant chemoradiation (NCRT) and total neoadjuvant therapy (TNT) has been associated with decreasing number of LNH. We hypothesize that as tumor response to neoadjuvant therapy increases, the optimum for LNH to achieve appropriate nodal staging should decrease.

METHODS

Patients with clinical stage III rectal adenocarcinoma who underwent NCRT/TNT followed by resection were identified from the National Cancer Database. A JoinPoint regression analysis was used to determine the LNH for each tumor regression grade (TRG) category beyond which the rate of positive nodes does not significantly change.

RESULTS

Thirteen thousand four hundred and twenty-six patients met inclusion criteria. Of these, 2406 (17.9%) achieved TRG 0 or ypT0 and 8210 (61.2%) achieved ypN0. Collectively, 2043 patients (15.2%) were reported to have a pathologic complete response (ypT0 ypN0). Positive pathologic nodes were found in 15%, 23%, 31%, 54%, and 53% as ypT stage increased from ypT0 to ypT4, respectively. Similarly, ypN+ rates were 15%, 36%, 41%, and 55% in TRG 0-3. No JoinPoint was identified for TRG 0, whereas inflection points were found at 6-10 nodes for TRG1 (p = 0.002) and TRG 2 (p = 0.016), and at 11-15 nodes for TRG 3.

CONCLUSION

The benchmark of retrieving 12 nodes in resectable stage III rectal cancer is not consistently achieved after NCRT/TNT. We demonstrate that the LNH requirement to establish accurate pathologic nodal staging can vary depending on the tumor response to neoadjuvant therapies.