Prognostic radiomic signature for head and neck cancer: Development and validation on a multi-centric MRI dataset.

BACKGROUND AND PURPOSE: Prognosis in locally advanced head and neck cancer (HNC) is currently based on TNM staging system and tumor subsite. However, quantitative imaging features (i.e., radiomic features) from magnetic resonance imaging (MRI) may provide additional prognostic info. The aim of this work is to develop and validate an MRI-based prognostic radiomic signature for locally advanced HNC. MATERIALS AND METHODS: Radiomic features were extracted from T1- and T2-weighted MRI (T1w and T2w) using the segmentation of the primary tumor as mask. In total 1072 features (536 per image type) were extracted for each tumor. A retrospective multi-centric dataset (n = 285) was used for features selection and model training. The selected features were used to fit a Cox proportional hazard regression model for overall survival (OS) that outputs the radiomic signature. The signature was then validated on a prospective multi-centric dataset (n = 234). Prognostic performance for OS and disease-free survival (DFS) was evaluated using C-index. Additional prognostic value of the radiomic signature was explored. RESULTS: The radiomic signature had C-index = 0.64 for OS and C-index = 0.60 for DFS in the validation set. The addition of the radiomic signature to other clinical features (TNM staging and tumor subsite) increased prognostic ability for both OS (HPV- C-index 0.63 to 0.65; HPV+ C-index 0.75 to 0.80) and DFS (HPV- C-index 0.58 to 0.61; HPV+ C-index 0.64 to 0.65). CONCLUSION: An MRI-based prognostic radiomic signature was developed and prospectively validated. Such signature can successfully integrate clinical factors in both HPV+ and HPV- tumors.

Privacy-preserving distributed learning of radiomics to predict overall survival and HPV status in head and neck cancer.

A major challenge in radiomics is assembling data from multiple centers. Sharing data between hospitals is restricted by legal and ethical regulations. Distributed learning is a technique, enabling training models on multicenter data without data leaving the hospitals ("privacy-preserving" distributed learning). This study tested feasibility of distributed learning of radiomics data for prediction of two year overall survival and HPV status in head and neck cancer (HNC) patients. Pretreatment CT images were collected from 1174 HNC patients in 6 different cohorts. 981 radiomic features were extracted using Z-Rad software implementation. Hierarchical clustering was performed to preselect features. Classification was done using logistic regression. In the validation dataset, the receiver operating characteristics (ROC) were compared between the models trained in the centralized and distributed manner. No difference in ROC was observed with respect to feature selection. The logistic regression coefficients were identical between the methods (absolute difference <10-7). In comparison of the full workflow (feature selection and classification), no significant difference in ROC was found between centralized and distributed models for both studied endpoints (DeLong p > 0.05). In conclusion, both feature selection and classification are feasible in a distributed manner using radiomics data, which opens new possibility for training more reliable radiomics models.

Endovascular treatment of iliac artery rupture after septic embolization.

A 56-year man with multiple comorbidities and recent septic embolization presented claudication intermittens (Rutherford3) at right lower limb and complaint in right lower quadrant at abdominal palpation. Duplex and computed tomography angiogram (CTA) showed a 64mm-pseudo-aneurysm (PA) originating from right common iliac artery, occlusion of external iliac and patency of hypogastric artery. An urgent endovascular approach was preferred. By left brachial percutaneous access, coil embolization (Balt SPI™ and Cook MReye™) of hypogastric and common iliac artery and deployment of Amplatzer Vascular PlugII™ into the common iliac artery were performed. Completion angiography showed exclusion of PA. One-day, 3­day and 1-month CTA proofed no vascularization of PA. No fever, no leukocytosis, no signs of infection occurred during follow-up and 10-month CTA showed the complete resolution of pseudoaneurysm.

Gallstone ileus: literature review.

Gallstone ileus is a rare case of mechanical intestinal obstruction observed in patients with history of cholelithiasis or cholecystitis. Its diagnosis is difficult and it is characterized by high mortality rate. Diagnostic Imaging plays an important role in the management of patients with suspected gallstone ileus because an early diagnosis could reduce the mortality. Abdominal Computed Tomography (CT) is the preferred modality because of its rapid diagnosis. Surgery remains the gold standard treatment.

Defecography: a still needful exam for evaluation of pelvic floor diseases.

The aim of this discussion is to describe what is a defecography, how we have to perform it, what can we see and to present the main physio-pathological illnesses of pelvic floor and anorectal region that can be studied with this method and its advantages over other screening techniques. Defecography is a contrastographic radiological examination that highlights structural and functional pelvic floor diseases. Upon preliminary ileum-colic opacification giving to patient radiopaque contrast, are first acquired static images (at rest, in maximum voluntary contraction of the pelvic muscles, while straining) and secondarily dynamic sequences (during evacuation), allowing a complete evaluation of the functionality of the anorectal region and the pelvic floor. Defecography is an easy procedure to perform widely available, and economic, carried out in conditions where the patient experiences symptoms, the most realistic possible. It can be still considered reliable technology and first choice in many patients in whom the clinic alone is not sufficient and it is not possible or necessary to perform a study with MRI.

Imaging of congenital pulmonary malformations.

Congenital pulmonary malformations represent a broad spectrum of anomalies that may result in varied clinical and pathologic pictures, ranging from recurrent pulmonary infections and acute respiratory distress syndrome, which require timely drug therapy, up to large space-occupying lesions needing surgical treatment. This classification includes three distinct anatomical and pathological entities, represented by Congenital Cystic Adenomatoid Malformation, Bronchopulmonary Sequestration and Congenital Lobar Emphysema. The final result in terms of embryological and fetal development of these alterations is a Congenital Lung Hypoplasia. Since even Bronchial Atresia, Pulmonary Bronchogenic Cysts and Congenital Diaphragmatic Hernias are due to Pulmonary Hypoplasia, these diseases will be discussed in this review (1, 2).

An uncommon cause of ascites: uroperitoneum from iatrogenic bladder fistula detected by CT urography.

We report the case of a female who underwent laparoscopic hysterectomy and was referred to the emergency department with massive ascites 10 days later. Anamnestic background and clinical presentation suggested the occurrence of a urinary lesion, which was investigated by CT urography. CT urography with ultra-late excretory phase showed the leakage of iodinated contrast agent from the bladder dome into the peritoneal cavity, as expected in uroperitoneum from iatrogenic bladder laceration. CT cystography is the reference standard for the assessment of bladder leakage; however, this technique is quite invasive, time consuming and does not provide a panoramic overview of the entire excretory system. Conversely, CT urography provides a complete overview of the entire excretory system by means of an optimized protocol with optional ultra-late acquisition to gain adequate bladder distension and depict minor urinary leakage.

Evolution of MIR168 paralogs in Brassicaceae.

BACKGROUND: In plants, expression of ARGONAUTE1 (AGO1), the catalytic subunit of the RNA-Induced Silencing Complex responsible for post-transcriptional gene silencing, is controlled through a feedback loop involving the miR168 microRNA. This complex auto-regulatory loop, composed of miR168-guided AGO1-catalyzed cleavage of AGO1 mRNA and AGO1-mediated stabilization of miR168, was shown to ensure the maintenance of AGO1 homeostasis that is pivotal for the correct functioning of the miRNA pathway. RESULTS: We applied different approaches to studying the genomic organization and the structural and functional evolution of MIR168 homologs in Brassicaeae. A whole genome comparison of Arabidopsis and poplar, phylogenetic footprinting and phylogenetic reconstruction were used to date the duplication events originating MIR168 homologs in these genomes. While orthology was lacking between Arabidopsis and poplar MIR168 genes, we successfully isolated orthologs of both loci present in Arabidopsis (MIR168a and MIR168b) from all the Brassicaceae species analyzed, including the basal species Aethionema grandiflora, thus indicating that (1) independent duplication events took place in Arabidopsis and poplar lineages and (2) the origin of MIR168 paralogs predates both the Brassicaceae radiation and the Arabidopsis alpha polyploidization. Different phylogenetic footprints, corresponding to known functionally relevant regions (transcription starting site and double-stranded structures responsible for microRNA biogenesis and function) or for which functions could be proposed, were found to be highly conserved among MIR168 homologs. Comparative predictions of the identified microRNAs also indicate extreme conservation of secondary structure and thermodynamic stability. CONCLUSION: We used a comparative phylogenetic footprinting approach to identify the structural and functional constraints that shaped MIR168 evolution in Brassicaceae. Although their duplication happened at least 40 million years ago, we found evidence that both MIR168 paralogs have been maintained throughout the evolution of Brassicaceae, most likely functionally as indicated by the extremely high conservation of functionally relevant regions, predicted secondary structure and thermodynamic profile. Interestingly, the expression patterns observed in Arabidopsis indicate that MIR168b underwent partial subfunctionalization as determined by the experimental characterization of its expression pattern provided in this study. We found further evolutionary evidence that pre-miR168 lower stem (the RNA-duplex structure adjacent to the miR-miR* stem) is significantly longer than animal lower stems and probably plays a relevant role in multi-step miR168 biogenesis.

Analysis of the molecular basis of flowering time variation in Arabidopsis accessions.

Allelic variation at the FRI (FRIGIDA) and FLC (FLOWERING LOCUS C) loci are major determinants of flowering time in Arabidopsis accessions. Dominant alleles of FRI confer a vernalization requirement causing plants to overwinter vegetatively. Many early flowering accessions carry loss-of-function fri alleles containing one of two deletions. However, some accessions categorized as early flowering types do not carry these deletion alleles. We have analyzed the molecular basis of earliness in five of these accessions: Cvi, Shakhdara, Wil-2, Kondara, and Kz-9. The Cvi FRI allele carries a number of nucleotide differences, one of which causes an in-frame stop codon in the first exon. The other four accessions contain nucleotide differences that only result in amino acid substitutions. Preliminary genetic analysis was consistent with Cvi carrying a nonfunctional FRI allele; Wil-2 carrying either a defective FRI or a dominant suppressor of FRI function; and Shakhdara, Kondara, and Kz-9 carrying a functional FRI allele with earliness being caused by allelic variation at other loci including FLC. Allelic variation at FLC was also investigated in a range of accessions. A novel nonautonomous Mutator-like transposon was found in the weak FLC allele in Landsberg erecta, positioned in the first intron, a region required for normal FLC regulation. This transposon was not present in FLC alleles of most other accessions including Shakhdara, Kondara, or Kz-9. Thus, variation in Arabidopsis flowering time has arisen through the generation of nonfunctional or weak FRI and FLC alleles.