Dynamic Contrast Enhanced MRI as a Biomarker of Tumor Response and Oncologic Outcomes in Head and Neck Cancer: Results of a Single Institution Prospective Imaging Study

PURPOSE/OBJECTIVE(S)

We aim to determine the correlation between vascular parameters of Dynamic contrast enhanced (DCE) MRIs and tumor response and outcomes in head and neck (HNC) patients treated with definitive radiation therapy (RT).

MATERIALS/METHODS

Eighty-two HNC patients are included in this prospective study in one institute. All patients had malignant head and neck neoplasm indicative of curative- intent treatment. Patients were imaged using MRIs pre-, mid-, and post-RT completion at 8-12 weeks. T2-weighted sequences were used for tumor contouring then it was co-registered to respective DCE images. The response to treatment was checked at mid-radiotherapy (mid-RT) and at the end of RT. Mid-RT MRI was co-registered to baseline images and the manually segmented baseline primary tumor regions of interest were propagated to mid-RT images. Quantitative maps (Ktrans, Kep, Ve and Vp) were generated with the extended Tofts pharmacokinetic models and were used for analysis. These vascular parameters were presented as a mean value and percentile using histogram analysis and the following parameters were extracted using an in-house programming environment script: mean, 5th, 10th, 20th, 30th, 40th, 50th (i.e., median), 60th, 70th, 80th, 90th, 95th percentile. The non-parametric Wilcoxon signed-rank test was used to assess the changes of mid-RT DCE parameters compared to baseline. Recursive partitioning analysis (RPA) was used to identify the delta DCE threshold associated with relapse. We assessed the identified thresholds' correlation with oncological and survival endpoints using Cox regression with and without standard clinical variables.

RESULTS

The median age for patients is 61 years old (33-78 range). Never smokers are 39 (47%), 35 (43%) are former smoker and 8 (10%) are current smoker with a mean value of 14 pack per year and 26 standard deviations. Using AJCC 8th edition, 39 (47%) are stage I and 19 (23%) are stage II and stage III and IV are 15 (18%) and 9 (10%) respectively. HPV positive are 72 (88%). For patients with GTV-P at baseline (n = 60), 11 (18%) had mid-RT CR at the primary site which increased to 50 (83%) post-RT. The LC and RFS for the entire cohort were 91.4%, and 79.2% respectively. In GTV-P, none of the pre-radiotherapy DCE parameters were correlated with LC or RFS. Wilcoxon signed rank test was statistically significant in 80, 90 and 95 percentiles with (p<0.05). RPA analysis identified different thresholds for each DCE parameter, and its inclusions to the multivariate model improved its performance. In GTV-P, RPA analysis identified ΔKtrans 40 percentiles >15.6% at mid-RT as the most significant point. When this value of ΔKtrans added to the multivariate analysis it was associated with a significantly better model performance in RFS (p = 0.00001).

CONCLUSION

DCE parameters are a very promising tool to correlate with response and outcomes in H&N cancer patients. Future work is warranted for external validation of our findings.

Deep Learning Based Prognostic Prediction in Oropharyngeal Cancer Patients Using Multiparametric MRI Inputs

PURPOSE/OBJECTIVE(S)

While prognostic outcomes for oropharyngeal cancer (OPC) patients have improved in recent years, patients still face a non-negligible risk of disease recurrence or death. Accurately predicting post-therapy prognosis would be highly valuable for risk stratification and treatment guidance for OPC patients. Recent studies using PET/CT data have demonstrated the effectiveness of large-scale, end-to-end image-based deep learning (DL) models for predicting progression-free survival (PFS) in OPC patients. Multiparametric MRI (mpMRI), which combines anatomical and functional MRI sequences, has the potential to offer similar results, and has the added advantage of high-frequency longitudinal imaging capabilities, such as through MR-Linac devices. Therefore, this study aimed to develop a DL model using mpMRI data to predict PFS, and to evaluate the impact of anatomical and functional input channels on model performance.

MATERIALS/METHODS

From a large-scale head and neck cancer database at MD Anderson Cancer Center, treatment-naïve OPC patients with available pre-radiotherapy mpMRI imaging were selected for this study. mpMRI images used for this study included T2-weighted images (T2) and apparent diffusion coefficient (ADC) maps. PFS event status was defined as having either a local, regional, or distant failure, and/or death; data were right censored if an event had not occurred. Images were resampled to the T2 resolution, normalized to a [-1,1] scale, and cropped to the field of view of the ADC image for use in DL models. A DL convolutional neural network model based on the DenseNet121 architecture from the Medical Open Network for AI (MONAI) Python package using a negative log-likelihood loss function was implemented. The model used mpMRI images as input channels and 20 output channels representing the different time intervals of the predicted PFS conditional probabilities of surviving that time interval; final PFS in days was obtained by summing the cumulative probability of surviving each interval times the interval duration. A 5-fold cross validation approach was used for model training and evaluation. Separate models using only T2, only ADC, and T2 + ADC channel inputs were compared. Model performance was measured using the C-index.

RESULTS

Out of 1154 patients, 404 met inclusion criteria. The overall PFS event rate was 16%. Median C-index values from the 5-fold cross validation were 0.62, 0.67, and 0.69 for the ADC, T2, and T2+ADC models, respectively.

CONCLUSION

Using large-scale datasets and open-source DL implementations, we find that OPC PFS prediction models using mpMRI data yield modest but comparable performance to existing models (i.e., state-of-the-art reference performance using PET/CT). Moreover, combining mpMRI channels may increase the performance of models for OPC prognostic prediction. Future work will involve integration of additional timepoints, additional mpMRI images, clinical variables, and saliency maps.

Assessment of Dynamic Contrast Enhanced (DCE) MRI for Detection of Radiotherapy Induced Alteration in Mandibular Vasculature

PURPOSE/OBJECTIVE(S)

We aim to determine the kinetics of DCE-MRI changes in various mandibular risk volumes based on radiation (RT) dose received.

MATERIALS/METHODS

Eighty-eight head and neck cancer (HNC) patients (Pts) who underwent definitive RT were enrolled in this prospective study after IRB approval and informed consent. Images were acquired at pre-RT (Baseline), 3 weeks after RT start date (Mid-RT), 3 mos post-RT (PostRT1), and 6 mos post-RT (PostRT2). Manually segmented mandibular volumes on T2-weighted images were propagated to co-registered DCE-MRIs. Planning CTs and dose grids were also co-registered to corresponding baseline T2 images to create 3-D dose subvolumes. These were used to create 3 risk subvolumes; <30 Gy, 30-50 Gy, and >50 Gy ROIs. DCE images of different timepoints (TPs) were deformably co-registered and the dose subvolumes were propagated to each TP. We used the extended-Tofts model to generate the vascular quantitative maps (Ktrans and Ve). Each subvolume histogram parameters were extracted at each TP. Wilcoxon Signed Rank test was used to compare the changes at different TPs compared to baseline. We classified Pts' delta parameters at different TPs -based on our prior extensive QA assessment- into Pts with stable vascular profile (±25% change), Pts with significant increase (>25% change) and Pts with significant decrease (<-25%). Chi-square test was used to assess the change at different TPs.

RESULTS

For <30 Gy subvolumes, there were no significant changes (p > 0.05) in the studied DCE parameters at all TPs except a significant decrease (p < 0.001) in median Ktrans at PostRT2. For 30-50 Gy subvolumes, there was a significant increase in median Ktrans that started at MidRT (p = 0.006) and continued at PostRT1 (p = 0.04) but recovered to baseline values at PostRT2. Median Ve on the other hand only showed significant increase at PostRT1 (p = 0.001), but other TPs were not significantly different compared to baseline. Similarly, subvolumes >50 Gy showed same kinetics as in 30-50 Gy with significant increase of Ktrans at MidRT and PostRT1 and significant increase in Ve in only PostRT1 (P <0.05). For <30 Gy, there was significant increase in the number of Pts with stable or decrease in Ktrans at PostRT2 compared to earlier TPs (70% vs. 60% at PostRT1 and 54% at MidRT p = 0.003). 30-50 Gy subvolumes showed similar profile like <30 Gy with significant increase in the percentage of Pts with recovery at PostRT2. However, for >50 Gy, there was no significant increase in the number of Pts who recovered at PostRT2 (p = 0.3). Ve showed no significant increase in the percentage of Pts with recovery at different TPs (p > 0.05).

CONCLUSION

Results showed that for all dose mandibular subvolumes, there is an acute vascular insult that tends to recover at +6 months post-RT except for a selective group of patients who continue to have persistence of the vascular insult at high dose subvolumes. These findings are of importance for future selection of high risk population for prophylactic intervention against osteoradionecrosis.

Effect of Norplant implants on the pituitary-adrenal axis function and reserve capacity

The present work investigated the effects of Norplant implants on the pituitary-adrenal function among 15 users of Norplant implants prior to and 6 months after insertion of the implants. Serum cortisol levels and their diurnal variations, ACTH and 24-h urinary 17-ketosteroids, ketogenic steroids, 17-hydroxy steroids, and creatinine, were measured. Also, a dynamic test (the 5-h Synacthen depot = ACTH stimulation test) was done before and 6 months after implants insertion. The 9 a.m. cortisol levels were blunted (within the normal ranges) while the 6 p.m. values were unaltered. The 24-h urinary ketogenic, hydroxy, and ketosteroids were also unchanged after Norplant implants use. The ACTH stimulation test showed a decreased adrenal response which was also within normal ranges. These data should raise the question related to suprarenal response to acute or prolonged stresses, such as surgical operations or shock in women using Norplant implants.

Ocular histoplasmosis due to Histoplasma farciminosum in Egyptian donkeys

In this study 19 donkeys suffering from face excoriations below the medial canthas and lesions in the lacrymal apparatus were subjected to clinical radiological and microbiological investigations. Also histopathological examination of biopsy materials from ocular lesions were made. Eleven out of 19 donkeys (57.9%) showed specific lesions in the lacrymal apparatus. Mycological examination revealed the isolation of Histoplasma cells from 10 out of 19 examined cases. The isolated Histoplasma culture, although not completely identical to H. farciminosum, was more related to this than to other Histoplasma species. Histopathological examination revealed the presence of marked tissue infiltration by lymphocytes, monocytes and macrophages. Also the fungal organism appeared as double-contoured yeast cells lying within macrophages and giant cells.

Urinary hormonal profile during the first cycle of low-dose oral contraceptive pills in women

Ovarian function was studied in ten normal fertile women before and during the first cycle on a low-dose micropill containing 30 mcg ethinyl estradiol and 150 mcg L-norgestrel. In a control cycle and the first treatment cycle, steroid metabolites estrone-3-glucuronide (E1-3G) and pregnanediol-3 alpha-glucuronide (Pd-3G) were measured in daily early morning urine (EMU) samples. Also, luteinizing hormone (LH) was estimated during the expected periovulatory period. During the first cycle of micropill intake, ovarian function was suppressed in all cases. This is evidenced by significantly lower E1-3G and Pd-3G and absent midcycle LH peak compared to control cycles. The pattern of steroid metabolites was almost flat with no peaks. It is concluded that there is no need to cover the first cycle of micropill intake with other contraceptive methods.

Clinicopathological studies on neurectomy in equids

Clinical and pathological changes following neurectomy were studied experimentally in 46 male and female equids. Sixty-three operations were performed using either the traditional or the Fackelman and Clodius methods of neurectomy. The effect of arteriovenous ligation was studied in 12 animals and 20 angiograms were performed post mortem to study the arterial pattern of the extremities of the operated limb. Neuroma formation (31 cases) and sloughing of the hoof (five cases) were the two main untoward sequelae. Neurectomy by the technique of Fackelman and Clodius proved superior to the traditional method. No essential changes were observed after ligation of the blood vessels, except in one case where collateral circulation was established.

Effect of heat on uterine contractions during normal labor

The effect of local application of heat on the abdominal wall on uterine activity was evaluated in 15 full-term multiparous women early in the first stage of labor. Cardiotocographic monitoring showed that heat induces a significant increase in uterine activity without causing any abnormal fetal heart changes. The stimulated contractions return back to base line level following removal of heat. The application of heat on the abdominal wall of women in early labor appears to offer a new non-pharmacological modality for the stimulation of uterine activity.

[Onchocerca raillieti n.sp. (Filarioidea) from a domestic donkey in Africa]

Onchocerca raillieti sp. n. (Filarioidea), from the domestic donkey (Equus asinus) in Africa, is described. The species is compared to O. bohmi (Supperer, 1953) n.comb, O. reticulata Diesing, 1841, O. cervicalis Railliet et Henry, 1910, O. flexuosa (Wedl, 1856) and O. armillata Railliet et Henry, 1909 and can be differentiated by numerous characters of which the most important are the anterior region of the female (which is straight and slender, 6 to 8 cm long, and bears longitudinal striae) and the 10 symmetrically arranged pairs of caudal papillae. O. raillieti seems to be a primitive species by several characters (caudal papillae, cervical papillae, oesophagus, vulva and cuticle.)