We have constructed a Fourier-transform spectrometer (FTS) operating between 50 GHz and 330 GHz with minimum volume ($355\times 260\times 64\mathrm{mm}$) and weight (5.9 kg) while maximizing optical throughput ($100{\mathrm{mm}}^2\mathrm{sr}$) and optimizing the spectral resolution (4 GHz). This FTS is designed as a polarizing Martin–Puplett interferometer with unobstructed input and output in which both input polarizations undergo interference. The instrument construction is simple with mirrors milled on the box walls and one motorized stage as the single moving element. We characterize the performance of the FTS, compare the measurements to an optical simulation, and discuss features that relate to details of the FTS design. The simulation is also used to determine the tolerance of optical alignments for the required specifications. We detail the FTS mechanical design and provide the control software as well as the analysis code online.

Background: Sanguinate, a bovine PEGylated carboxyhemoglobin-based oxygen carrier with vasodilatory, oncotic and anti-inflammatory properties designed to release oxygen in hypoxic tissue, was tested to determine if it improves infarct volume, collateral recruitment and blood flow to the ischemic core in hyperacute middle cerebral artery occlusion (MCAO). Methods: Under an IACUC approved protocol, 14 mongrel dogs underwent endovascular permanent MCAO. Seven received Sanguinate (8 mL/kg) intravenously over 10 min starting 30 min following MCAO and seven received a similar volume of normal saline. Relative cerebral blood flow (rCBF) was assessed using neutron-activated microspheres prior to MCAO, 30 min following MCAO and 30 min following intervention. Pial collateral recruitment was scored and measured by arterial arrival time (AAT) immediately prior to post-MCAO microsphere injection. Diffusion-weighted 3T MRI was used to assess infarct volume approximately 2 hours after MCAO. Results: Mean infarct volumes for control and Sanguinate-treated subjects were 4739 mm³ and 2585 mm³ (p=0.0443; r²=0.687), respectively. Following intervention, rCBF values were 0.340 for controls and 0.715 in the Sanguinate group (r²=0.536; p=0.0064). Pial collateral scores improved only in Sanguinate-treated subjects and AAT decreased by a mean of 0.314 s in treated subjects and increased by a mean of 0.438 s in controls (p<0.0276). Conclusion: Preliminary results indicate that topload bolus administration of Sanguinate in hyperacute ischemic stroke significantly improves infarct volume, pial collateral recruitment and CBF in experimental MCAO immediately following its administration.

Recently, there has been tremendous interest on the use of large language models (LLMs) in radiology. LLMs have been employed for various applications in cancer imaging, including improving reporting speed and accuracy via generation of standardized reports, automating the classification and staging of abnormal findings in reports, incorporating appropriate guidelines, and calculating individualized risk scores. Another use of LLMs is their ability to improve patient comprehension of imaging reports with simplification of the medical terms and possible translations to multiple languages. Additional future applications of LLMs include multidisciplinary tumor board standardizations, aiding patient management, and preventing and predicting adverse events (contrast allergies, MRI contraindications) and cancer imaging research. However, limitations such as hallucinations and variable performances could present obstacles to widespread clinical implementation. Herein, we present a review of the current and future applications of LLMs in cancer imaging, as well as pitfalls and limitations.

Background This study tests the hypothesis that simultaneous cerebral blood pressure elevation and potent vasodilation augments perfusion to ischemic tissue in acute ischemic stroke and it varies by degree of pial collateral recruitment. Methods Fifteen mongrel canines were included. Subjects underwent permanent middle cerebral artery occlusion; pial collateral recruitment was scored before treatment. Seven treatment subjects received a continuous infusion of norepinephrine (0.1–1.52 µg/kg/min; titrated 25–45 mmHg above baseline mean arterial pressure while keeping systolic blood pressure below 180 mmHg) and hydralazine (20 mg) starting 30 min post-occlusion. Perfusion (cerebral blood flow—CBF) was evaluated with quantitative dynamic susceptibility contrast MRI 2.5 hours post-occlusion to produce images in mL/100 g/min, and relative CBF measured as ratios. Mean region of interest (ROI) values were reported, and compared and subject to regression analysis to elucidate trends. Results Differences in quantitative CBF (qCBF) between treatment and control group varied by degree of pial collateral recruitment, based on Wilcoxon rank sum scores and regression model fit. For poorly collateralized subjects, ipsilateral anatomic, core infarct, and penumbra regions showed treatment with higher qCBF, raised above the ischemic threshold, compared with the control, while well collateralized subjects showed a paradoxical decrease maintained above the ischemic threshold for neuronal death. qCBF on the contralateral side increased regardless of collateralization. Conclusion Results suggest that perfusion can be augmented in ischemic stroke with norepinephrine and hydralazine. Perfusion augmentation depends on degree of collateralization and territory in question, with some evidence of vascular steal.

BACKGROUND AND PURPOSE: In ischemic stroke, leptomeningeal collaterals can provide delayed and dispersed compensatory blood flow to tissue-at-risk despite an occlusion and can impact treatment response and infarct growth. The purpose of this work is to test the hypothesis that inclusion of this delayed and dispersed flow with an appropriately calculated Local Arterial Input Function (Local-AIF) is needed to quantify the degree of collateral blood supply in tissue distal to an occlusion. MATERIALS AND METHODS: Seven experiments were conducted in a pre-clinical middle cerebral artery occlusion model. Dynamic susceptibility contrast MRI was imaged and post-processed to yield quantitative cerebral blood flow (qCBF) maps with both a traditionally chosen single arterial input function applied globally to the whole brain (i.e. “Global-AIF”) and a delay and dispersion corrected AIF (i.e. “Local-AIF”) that is sensitive to retrograde flow. Leptomeningeal collateral arterial recruitment was quantified with a pial collateral score from x-ray angiograms, and infarct growth calculated from serially acquired diffusion weighted MRI scans. RESULTS: The degree of collateralization at x-ray correlated more strongly with qCBF using the Local-AIF in the ischemic penumbra (R²=0.81) than traditionally chosen Global-AIF (R²=0.05). qCBF using a Local-AIF was negatively correlated (less infarct progression as perfusion increased) with infarct growth (R² = 0.79) more strongly than a Global-AIF (R²=0.02). CONCLUSIONS: In acute stroke, qCBF calculated with a Local-AIF is more accurate for assessing tissue status and collateral supply than traditionally chosen Global-AIFs. These findings support use of a Local-AIF that corrects for delayed and dispersed retrograde flow in determining quantitative tissue perfusion with collateral supply in occlusive disease. ABBREVIATIONS: MRI = magnetic resonance imaging; DSC = dynamic susceptibility contrast; PCS = pial collateral score; MCAO = middle cerebral artery occlusion; MCA = middle cerebral artery; AIF = arterial input function; rCBF = relative cerebral blood flow; qCBF = quantitative cerebral blood flow

Intravoxel incoherent motion (IVIM) MRI allows for simultaneous assessment of tissue microcirculation (perfusion) and diffusion of water. In single‐center studies, IVIM has shown great potential for diagnosis, treatment outcome prediction, and treatment monitoring for many different diseases and organs. However, heterogeneity in data acquisition protocols, pre‐processing pipelines, and post‐processing routines yields differences in reported IVIM parameters, which has constrained large‐scale deployment of IVIM. Moreover, deploying IVIM protocols and analysis typically requires technical expertise, further challenging wider use, especially for clinicians. In this consensus paper, to accelerate the deployment of IVIM, we provide recommendations and harmonize protocols for brain, breast, kidney, liver, muscle, and pancreas IVIM studies. For this goal we organized multiple questionnaires and held a dedicated workshop. To ensure a level of standardized, reproducible results, without restricting innovation, we suggest a small subset of b ‐values to always be measured and analyzed separately, and to which more extensive b ‐value sampling can be added for advanced investigations. We further introduce detailed recommendations on acquisition protocols and analysis pipelines. To increase consistency, repeatability, and reproducibility, we highly recommend that these protocols and pipelines be deployed by scientists and clinicians for IVIM studies. For advanced users who desire different protocols or analysis approaches, we suggest adding results from our suggested protocols and analysis pipeline in the supplemental part of their paper to enable retrospective studies.