In this review we present the current status of ultrasound thermometry and ablation monitoring, with emphasis on the diverse approaches published in the literature and with an eye on which methods are closest to clinical reality. It is hoped that this review will serve as a guide to the expansion of sonographic methods for treatment monitoring and thermometry since the last brief review in 2007.

Recent observation of optical luminescence due to beta decay from suitable radiotracers has led to the possible development of new preclinical optical imaging methods. The generation of photons that can be detected using instrumentation optimized for bioluminescence imaging has been putatively associated with the Cerenkov effect. We describe the simultaneous utilization of fluorescence reporters to convert Cerenkov luminescence to longer wavelengths for better tissue penetration and also for modulating the luminescence spectrum for potential molecular imaging strategies.

Purpose: Magnetic resonance imaging has been recently used to examine the abnormalities of the placenta during pregnancy. Segmentation of the placenta and uterine cavity allows quantitative measures and further analyses of the organs. The objective of this study is to develop a segmentation method with minimal user interaction. Approach: We developed a fully convolutional neural network (CNN) for simultaneous segmentation of the uterine cavity and placenta in three dimensions (3D) while a minimal operator interaction was incorporated for training and testing of the network. The user interaction guided the network to localize the placenta more accurately. In the experiments, we trained two CNNs, one using 70 normal training cases and the other using 129 training cases including normal cases as well as cases with suspected placenta accreta spectrum (PAS). We evaluated the performance of the segmentation algorithms on two test sets: one with 20 normal cases and the other with 50 images from both normal women and women with suspected PAS. Results: For the normal test data, the average Dice similarity coefficient (DSC) was 92% and 82% for the uterine cavity and placenta, respectively. For the combination of normal and abnormal cases, the DSC was 88% and 83% for the uterine cavity and placenta, respectively. The 3D segmentation algorithm estimated the volume of the normal and abnormal uterine cavity and placenta with average volume estimation errors of 4% and 9%, respectively. Conclusions: The deep learning-based segmentation method provides a useful tool for volume estimation and analysis of the placenta and uterus cavity in human placental imaging.

Bioluminescent imaging (BLI) of cells expressing luciferase is a valuable noninvasive technique for investigating molecular events and tumor dynamics in the living animal. Current usage is often limited to planar imaging, but tomographic imaging can enhance the usefulness of this technique in quantitative biomedical studies by allowing accurate determination of tumor size and attribution of the emitted light to a specific organ or tissue. Bioluminescence tomography based on a single camera with source rotation or mirrors to provide additional views has previously been reported. We report here in vivo studies using a novel approach with multiple rotating cameras that, when combined with image reconstruction software, provides the desired representation of point source metastases and other small lesions. Comparison with MRI validated the ability to detect lung tumor colonization in mouse lung.

The electron-multiplying charge-coupled device (EMCCD) offers improved quantum efficiencies (40 to 95%) over a broader range of wavelengths (400 to 900 nm) and a higher intrinsic resolution (<100 mum using photon counting) when compared to photomultiplier tubes. The electron gain achieved in the multiplication register of an EMCCD effectively reduces the readout noise to less than 1 electron/pixel, making them sensitive to single photoelectrons. Our prototype camera uses the Texas Instruments Impactrontrade EMCCD model TC253SPD-B0 (7.4 mum square pixels) which is cooled under vacuum to -50degC using a four stage Peltier and liquid heat exchanger. Shuttered lens-coupling is used to image the optical light from a 3 mm thick monolithic CsI(Tl) crystal. Precise clocking for the EMCCD is provided by a National Instruments FPGA controller (PCI-7811R) and LabVIEW FPGA module (version 8.0). A custom built electronics box contains the clock driver circuitry and 16-bit video board for digital conversion of the video signal. Our optical coupling method differs from other EMCCD SPECT systems by using lenses rather than fiber optic bundles for transfer. TC253 characterization tests measured a maximum gain just over 1000times, dark current rate of 0.14 e/p/s, read noise of 18.2 e/p, and spurious charge generation of 4 e/p. A light integration intrinsic resolution of 110 mum FWHM was measured. Light integration images of a line phantom using a single pinhole collimator were used for SPECT reconstruction. We found the relative high spurious charge generation and low quantum efficiency of the TC253 made it incapable of photon counting for low energy sources using lens coupling.