Bone texture analysis using CT-simulation scans to individuate risk parameters for radiation-induced insufficiency fractures

This study deals with the role of texture analysis as a predictive factor of radiation-induced insufficiency fractures in patients undergoing pelvic radiation.

INTRODUCTION

This study aims to assess the texture analysis (TA) of computed tomography (CT) simulation scans as a predictive factor of insufficiency fractures (IFs) in patients with pelvic malignancies undergoing radiation therapy (RT).

METHODS

We performed an analysis of patients undergoing pelvic RT from January 2010 to December 2014, 24 of whom had developed pelvic bone IFs. We analyzed CT-simulation images using ImageJ macro software and selected two regions of interest (ROIs), which are L5 body and the femoral head. TA parameters included mean (m), standard deviation (SD), skewness (sk), kurtosis (k), entropy (e), and uniformity (u). The IFs patients were compared (1:2 ratio) with controlled patients who had not developed IFs and matched for sex, age, menopausal status, type of tumor, use of chemotherapy, and RT dose. A reliability test of intra- and inter-reader ROI TA reproducibility with the intra-class correlation coefficient (ICC) was performed. Univariate and multivariate analyses (logistic regression) were applied for TA parameters observed both in the IFs and the controlled groups.

RESULTS

Inter- and intra-reader ROI TA was highly reproducible (ICC > 0.90). Significant TA parameters on paired t test included L5 m (p = 0.001), SD (p = 0.002), k (p = 0.006), e (p = 0.004), and u (p = 0.015) and femoral head m (p < 0.001) and SD (p = 0.001), whereas on logistic regression analysis, L5 e (p = 0.003) and u (p = 0.010) and femoral head m (p = 0.027), SD (p = 0.015), and sex (p = 0.044).

CONCLUSIONS

In our experience, bone CT TA could be correlated to the risk of radiation-induced IFs. Studies on a large patient series and methodological refinements are warranted.

Assessment of response to chemoradiation therapy in rectal cancer using MR volumetry based on diffusion-weighted data sets: a preliminary report

PURPOSE

This study evaluated the feasibility of magnetic resonance (MR) volumetry using a diffusion-weighted data set (V(DWI)) and compared it with conventional T2-weighted volumetry (V(C)) in patients affected by rectal cancer treated with chemoradiation therapy (CHRT).

MATERIALS AND METHODS

Fourteen patients with a biopsy diagnosis of rectal cancer underwent MR examination before and after CHRT. T2-weighted images were used to extrapolate V(C). A diffusion-weighted (DW) sequence was acquired [spin-echo diffusion-weighted echo-planar imaging (SE-DW-EPI)] with a b-value of 800 s/mm(2) and volume (V(DWI)) was calculated by semiautomatic segmentation of tumour hyperintensity. Two radiologists independently assessed volumes and analysed data in order to establish interobserver agreement and compare and correlate volumes to tumour regression grade (TRG), as evaluable at pathological examination of the surgical specimen.

RESULTS

Interobserver agreement was 0.977 [(95% confidence interval (CI) 0.954-0.989) and 0.956 (95% CI 0.905-0.980) for V(C) and V(DWI) and 0.964 (95% CI 0.896-0.988) and 0.271 (95% CI-0.267 to 0.686) between V(C) and V(DWI) before and after CHRT. The correlation between TRG and V(C) and V(DWI) was, respectively, rho = 0.597 (p<0.05) and r(2)=0.156 (p=0.162) and rho=0.847 (p<0.001).

CONCLUSIONS

V(DWI) seems to be a promising tool for assessing response to CHRT in rectal cancer. Further studies on large series of patients are needed to refine the technique and evaluate its potential predictive value.

[Restaging brain computerized tomography after treatment of non-operable lung neoplasms]

PURPOSE

To assess the role of CT brain scans as a routine restaging procedure after primary, aggressive, drug or radiation therapy of unresectable lung cancer. If early, asymptomatic brain metastases are detected and treated, survival could be improved relative to the patients showing brain involvement in a later CT scan performed during the follow-up, at the onset of neurological symptoms.

MATERIAL AND METHODS

One hundred patients affected with lung cancer, unresectable on account of histology (small-cell carcinoma) or advanced stage (III, IV) were submitted to chemo- and/or radiotherapy, after a clinical staging including brain CT, which was negative in all patients. Brain CT was also repeated at the end of therapy (restaging), in the absence of any neurological symptom. Further scans were obtained during the subsequent follow-up only when clinical symptoms occurred, suggesting metastases to the brain. Survival values were analyzed in the patients whose brain involvement was detected during restaging, vs those showing symptomatic brain metastases during the follow-up.

RESULTS

Only 4 patients had asymptomatic metastases, diagnosed with the restaging brain CT scan. Their survival rate was significantly lower than that of the 20 patients whose brain involvement was shown by a follow-up CT scan, performed after the onset of neurological symptoms. However, death was rarely a consequence of brain metastases: primary or other metastatic sites were involved in the terminal events, in the greatest majority of these cases.

DISCUSSION AND CONCLUSIONS

The sudden, asymptomatic brain involvement, detected at restaging CT scan after primary therapy for unresectable lung cancer, does not correlate with a better prognosis than symptomatic metastases, diagnosed later with a follow-up CT obtained performed for clinical suspicion. Therefore the use of restaging CT scan is not warranted, as a routine procedure, except for the clinical trials intended to define optimal treatment schedules.