Assessing the added value of ADC, CBV and radiomic MR features for differentiation of pseudoprogression vs. true tumor progression in patients with glioblastoma

Background

Pseudoprogression (PsPD) is a major diagnostic challenge in the follow-up of patients with glioblastoma (GB) after chemo-radiotherapy (CRT). Conventional imaging signs and parameters derived from diffusion and perfusion-MRI have yet to prove their reliability in clinical practice for an accurate differential diagnosis. Here, we tested these parameters and combined them with radiomic features (RFs), clinical data, and MGMT-promoter methylation-status using machine- and deep-learning models to distinguish PsPD from PD.

Methods

In a single-center analysis, 105 patients with GB who developed a suspected imaging PsPD in the first 7 months after standard-CRT were identified retrospectively. Imaging data included standard MRI anatomical sequences, apparent diffusion coefficient (ADC) and normalized relative cerebral blood volume (nrCBV) maps. Median values (ADC, nrCBV) and RFs (all sequences) were calculated from deep-learning-based tumor segmentations. Generalized linear models with LASSO feature-selection and deep-learning models were built integrating clinical data, MGMT-methylation-status, median ADC and nrCBV values and RFs.

Results

A model based on clinical data and MGMT-methylation-status yielded an AUC=0.69 (95%CI 0.55-0.83) for detecting PsPD, and the addition of median ADC and nrCBV values resulted in a non-significant increase in performance (AUC=0.71,95%CI 0.57-0.85, p=0.416). Combining clinical/MGMT information with RFs derived from ADC, nrCBV and from all available sequences both resulted in significantly (both p<0.005) lower model performances, with AUC=0.52 (0.38-0.66) and AUC=0.54 (0.40-0.68), respectively. Deep-learning imaging models resulted in AUCs≤0.56.

Conclusion

Currently available imaging biomarkers could not reliably differentiate PsPD from true tumor progression in patients with glioblastoma; larger collaborative efforts are needed to build more reliable models.

[Update on collaborative autopsy-based research in German pathology, neuropathology, and forensic medicine]

BACKGROUND

Autopsies are a valuable tool for understanding disease, including COVID-19.

MATERIALS AND METHODS

The German Registry of COVID-19 Autopsies (DeRegCOVID), established in April 2020, serves as the electronic backbone of the National Autopsy Network (NATON), launched in early 2022 following DEFEAT PANDEMIcs.

RESULTS

The NATON consortium's interconnected, collaborative autopsy research is enabled by an unprecedented collaboration of 138 individuals at more than 35 German university and non-university autopsy centers through which pathology, neuropathology, and forensic medicine autopsy data including data on biomaterials are collected in DeRegCOVID and tissue-based research and methods development are conducted. More than 145 publications have now emerged from participating autopsy centers, highlighting various basic science and clinical aspects of COVID-19, such as thromboembolic events, organ tropism, SARS-CoV‑2 detection methods, and infectivity of SARS-CoV-2 at autopsy.

CONCLUSIONS

Participating centers have demonstrated the high value of autopsy and autopsy-derived data and biomaterials to modern medicine. The planned long-term continuation and further development of the registry and network, as well as the open and participatory design, will allow the involvement of all interested partners.

TMIC-27. GLUTAMATERGIC NEURON-GLIOMA SYNAPSES DRIVE BRAIN TUMOUR PROGRESSION

A network of communicating tumour cells established by tumour microtubes (TMs) is supposed to mediate relevant aspects of progression and resistance of incurable gliomas. Moreover, neuronal activity has been shown to foster malignant behavior of glioma cells by non-synaptic paracrine and autocrine mechanisms. Here, we report an unexpected direct communication channel between neurons and glioma cells in multiple disease models as well as in astrocytomas and glioblastomas (GBs) of adult patients: functional bona fide chemical synapses formed between presynaptic neurons and postsynaptic glioma cells. These neurogliomal synapses (NGS) show a typical synaptic ultrastructure, are located on TM networks, and produce depolarizing postsynaptic currents mediated by glutamate receptors of the AMPA subtype. AMPA-type glutamate receptors (AMPAR) are expressed by a molecularly and morphologically distinct subpopulation of network-integrated glioma cells. Increased neuronal activity under epileptic conditions ex vivo or neuronal optogenetic stimulation in vivo enhanced, while general anesthesia diminished synchronized calcium transients in TM-connected glioma networks. Accordingly, anesthesia reduced invasiveness of TM-positive tumour cells in mice. Genetic perturbation of AMPAR or chronic AMPAR inhibition by perampanel decreased glioma invasion and proliferation in mice and deletion of GluRII in Drosophila glioma increased survival. These findings reveal a hitherto unappreciated direct synaptic communication between neurons and glioma cells that appears relevant for brain tumour biology, implying new avenues for glioma treatment.

Activation of dopamine D1/D5 receptors facilitates the induction of presynaptic long-term potentiation at hippocampal output synapses

Encoding of novel information has been proposed to rely on the time-locked release of dopamine in the hippocampal formation during novelty detection. However, the site of novelty detection in the hippocampus remains a matter of debate. According to current models, the CA1 and the subiculum act as detectors and distributors of novel sensory information. Although most CA1 pyramidal neurons exhibit regular-spiking behavior, the majority of subicular pyramidal neurons fire high-frequency bursts of action potentials. The present study investigates the efficacy of dopamine D1/D5 receptor activation to facilitate the induction of activity-dependent long-term potentiation (LTP) in rat CA1 regular-spiking and subicular burst-spiking pyramidal cells. Using a weak stimulation protocol, set at a level subthreshold for the induction of LTP, we show that activation of D1/D5 receptors for 5-10 min facilitates LTP in subicular burst-spiking neurons but not in CA1 neurons. The results demonstrate that D1/D5 receptor-facilitated LTP is NMDA receptor-dependent, and requires the activation of protein kinase A. In addition, the D1/D5 receptor-facilitated LTP is shown to be presynaptically expressed and relies on presynaptic Ca(2+) signaling. The phenomenon of dopamine-induced facilitation of presynaptic NMDA receptor-dependent LTP in subicular burst-spiking pyramidal cells is in accordance with observations of the time-locked release of dopamine during novelty detection in this brain region, and reveals an intriguing mechanism for the encoding of hippocampal output information.

[18F-fluorodeoxyglucose positron emission tomography in colorectal cancer: value in primary staging and follow-up]

Positron emission tomography using 18F-fluorodeoxyglucose (FDG-PET) is a encouraging imaging technique allowing a highly sensitive whole-body search for malignant foci detected by their increased glucose metabolism compared with benign tissues. Several studies are now available that indicate its added value for diagnosis and staging of colorectal cancer. In all, patient management seems to be changed in 20-30% of patients who undergo Fluorodeoxyglucose positron emission tomography in addition to standard staging procedures. Fluorodeoxyglucose positron emission tomography is also useful in monitoring radiation therapy and chemotherapy. Regarding preoperative staging of primary colorectal cancer the literature is very limited.

Small bowel perforation after extracorporeal shockwave lithotripsy of an ureter stone

A 60-year-old man was treated by extracorporeal shock wave lithotripsy (ESWL) for an impacted ureter stone. Two days after the procedure he developed an acute abdomen. On laparotomy, a small bowel perforation in the area of an adhesion to the abdominal wall was found. The adherent intestinal segment was located exactly in the range of the ESWL field, so that excluding further reasons the shockwave lithotripsy must be assumed to be causative.