Multiscale X-ray phase-contrast tomography: From breast CT to micro-CT for virtual histology.

Phase-contrast imaging techniques address the issue of poor soft-tissue contrast encountered in traditional X-ray imaging. This can be accomplished with the propagation-based phase-contrast technique by employing a coherent photon beam, which is available at synchrotron facilities, as well as long sample-to-detector distances. This study demonstrates the optimization of propagation-based phase-contrast computed tomography (CT) techniques for multiscale X-ray imaging of the breast at the Elettra synchrotron facility (Trieste, Italy). Two whole breast mastectomy samples were acquired with propagation-based breast-CT using a monochromatic synchrotron beam at a pixel size of 60 µm. Paraffin-embedded blocks sampled from the same tissues were scanned with propagation-based micro-CT imaging using a polychromatic synchrotron beam at a pixel size of 4 µm. Images of both methodologies and of the same sample were spatially registered. The resulting images showed the transition from whole breast imaging with propagation-based breast-CT methodology to virtual histology with propagation-based micro-CT imaging of the same sample. Additionally, conventional histological images were matched to virtual histology images. Phase-contrast images offer a high resolution with low noise, which allows for a highly precise match between virtual and conventional histology. Furthermore, those techniques allow a clear discernment of breast structures, lesions, and microcalcifications, being a promising clinically-compatible tool for breast imaging in a multiscale approach, to either assist in the detection of cancer in full volume breast samples or to complement structure identification in paraffin-embedded breast tissue samples.

Tumour infiltrating lymphocytes and PD-L1 expression as potential predictors of outcome in patients with malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is a rare and aggressive form of tumour. Some mesotheliomas have been proven to be highly immunogenic. Here, we investigated the correlation between tumour infiltrating lymphocytes (TILs) or programmed cell death ligand 1 (PD-L1) expression with overall survival (OS) in patients with MPM. 62 Paraffin-embedded formalin fixed (PEFF) samples were analysed for TILs and PD-L1 expression. Patients were divided in 4 groups according to a cut-off of the percentage of TILs found per sample as measured by immunohistichemistry: "0" or absent (between 0 and 5%), "1" or low (between 6 and 25%), "2" or moderate (between 26 and 50%) and "3" or high (between 51 and 75%). OS was then correlated with different TILs' expression patterns. Moreover, PD-L1 expression was assessed within the tumour as well as in the adjacent stroma on the same samples. Higher expression of peritumoral TILs (Group 2 + 3) versus Group 0 and 1 correlated with improved OS (p-value = 0.02). On the contrary PD-L1 expression seemed to be inversely correlated with clinical outcomes, even in the absence of statistical significance (HR 1.76; p = 0.083 95% IC 0.92-3.36 in areas within the tumour; HR 1.60; p = 0.176 95%; IC 0.80-3.19 in areas within the stroma). No relationship between TILs and PD-L1 expression was identified. Our research supports the use of TILs and PD-L1 expression as potential outcome predictors in patients with MPM. The use of TILs and PD-L1 as biomarkers for checkpoint inhibitors' efficacy warrants future investigation.

Charcoal suspension tattoo: new tool for the localization of malignant laterocervical lymph nodes.

We present a retrospective study to evaluate safety and effectiveness of ultrasound (US)-guided tattooing with charcoal of suspicious laterocervical lymph nodes. When an open biopsy of a laterocervical lymph node is needed, the choice of the lymph node to excise and examine is fundamental to avoid rebiopsy. Surgeons tend to choose the most surgical approachable enlarged lymph node that does not always correspond to the one with worst echographic aspect. We present 16 cases of patients with laterocervical adenopathy with inconclusive or non-adequate results at fine needle aspiration cytology addressed to open biopsy. Those patients underwent US-guided preoperative injection of a charcoal suspension inside the lymph node to excise to mark it, and then excisional biopsy was performed. Sixteen marked lesions (100 %) were detected intraoperatively and dissected. The injected charcoal was detected intraoperatively in all cases. In 14 patients (87, 5 %) it was inside the lesion; in two cases (12, 5 %), the charcoal suspension was found in the tissues above the lesion. The procedure was well tolerated in all cases. No major procedure-related complications were encountered. US-guided charcoal tattooing is a new, safe, well-tolerated, and easy-to-perform technique for the marking of US suspicious laterocervical lymph nodes. This preliminary study shows a high technical success rate (76 %) and high percentage of intraoperative detection of marked lesions (100 %) with a low rate of complications.