Repeatability of metabolic tumor burden and lesion glycolysis between clinical readers.

The Metabolic Tumor Volume (MTV) and Tumor Lesion Glycolysis (TLG) has been shown to be independent prognostic predictors for clinical outcome in Diffuse Large B-cell Lymphoma (DLBCL). However, definitions of these measurements have not been standardized, leading to many sources of variation, operator evaluation continues to be one major source. In this study, we propose a reader reproducibility study to evaluate computation of TMV (& TLG) metrics based on differences in lesion delineation. In the first approach, reader manually corrected regional boundaries after automated detection performed across the lesions in a body scan (Reader M using a manual process, or manual). The other reader used a semi-automated method of lesion identification, without any boundary modification (Reader A using a semi- automated process, or auto). Parameters for active lesion were kept the same, derived from standard uptake values (SUVs) over a 41% threshold. We systematically contrasted MTV & TLG differences between expert readers (Reader M & A). We find that MTVs computed by Readers M and A were both concordant between them (concordant correlation coefficient of 0.96) and independently prognostic with a P-value of 0.0001 and 0.0002 respectively for overall survival after treatment. Additionally, we find TLG for these reader approaches showed concordance (CCC of 0.96) and was prognostic for over -all survival (p ≤ 0.0001 for both). In conclusion, the semi-automated approach (Reader A) provides acceptable quantification & prognosis of tumor burden (MTV) and TLG in comparison to expert reader assisted measurement (Reader M) on PET/CT scans.

A Phase 1b Adaptive Androgen Deprivation Therapy Trial in Metastatic Castration Sensitive Prostate Cancer.

Background: We hypothesize that cancer survival can be improved through adapting treatment strategies to cancer evolutionary dynamics and conducted a phase 1b study in metastatic castration sensitive prostate cancer (mCSPC). Methods: Men with asymptomatic mCSPC were enrolled and proceeded with a treatment break after achieving > 75% PSA decline with LHRH analog plus an NHA. ADT was restarted at the time of PSA or radiographic progression and held again after achieving >50% PSA decline. This on-off cycling of ADT continued until on treatment imaging progression. Results: At data cut off in August 2022, only 2 of the 16 evaluable patients were off study due to imaging progression at 28 months from first dose of LHRH analog for mCSPC. Two additional patients showed PSA progression at 12.4 and 20.5 months and remain on trial. Since none of the 16 patients developed imaging progression at 12 months, the study succeeded in its primary objective of feasibility. The secondary endpoints of median time to PSA progression and median time to radiographic progression have not been reached at a median follow up of 26 months. Conclusions: It is feasible to use an individual's PSA response and testosterone levels to guide intermittent ADT in mCSPC.

Absorbable versus nonabsorbable sutures for the Krackow suture repair of acute Achilles tendon rupture: a prospective randomized controlled trial.

AIMS: Although absorbable sutures for the repair of acute Achilles tendon rupture (ATR) have been attracting attention, the rationale for their use remains insufficient. This study prospectively compared the outcomes of absorbable and nonabsorbable sutures for the repair of acute ATR. METHODS: A total of 40 patients were randomly assigned to either braided absorbable polyglactin suture or braided nonabsorbable polyethylene terephthalate suture groups. ATR was then repaired using the Krackow suture method. At three and six months after surgery, the isokinetic muscle strength of ankle plantar flexion was measured using a computer-based Cybex dynamometer. At six and 12 months after surgery, patient-reported outcomes were measured using the Achilles tendon Total Rupture Score (ATRS), visual analogue scale for pain (VAS pain), and EuroQoL five-dimension health questionnaire (EQ-5D). RESULTS: Overall, 37 patients completed 12 months of follow-up. No difference was observed between the two groups in terms of isokinetic plantar flexion strength, ATRS, VAS pain, or EQ-5D. No re-rupture was observed in either group. CONCLUSION: The use of absorbable sutures for the repair of acute ATR was not inferior to that of nonabsorbable sutures. This finding suggests that absorbable sutures can be considered for the repair of acute ATRs. Cite this article: Bone Joint J 2022;104-B(8):938-945.

In Vivo Imaging of Rat Vascularity with FDG-Labeled Erythrocytes.

Microvascular disease is frequently found in major pathologies affecting vital organs, such as the brain, heart, and kidneys. While imaging modalities, such as ultrasound, computed tomography, single photon emission computed tomography, and magnetic resonance imaging, are widely used to visualize vascular abnormalities, the ability to non-invasively assess an organ's total vasculature, including microvasculature, is often limited or cumbersome. Previously, we have demonstrated proof of concept that non-invasive imaging of the total mouse vasculature can be achieved with 18F-fluorodeoxyglucose (18F-FDG)-labeled human erythrocytes and positron emission tomography/computerized tomography (PET/CT). In this work, we demonstrate that changes in the total vascular volume of the brain and left ventricular myocardium of normal rats can be seen after pharmacological vasodilation using 18F-FDG-labeled rat red blood cells (FDG RBCs) and microPET/CT imaging. FDG RBC PET imaging was also used to approximate the location of myocardial injury in a surgical myocardial infarction rat model. Finally, we show that FDG RBC PET imaging can detect relative differences in the degree of drug-induced intra-myocardial vasodilation between diabetic rats and normal controls. This FDG-labeled RBC PET imaging technique may thus be useful for assessing microvascular disease pathologies and characterizing pharmacological responses in the vascular bed of interest.

Comparison of Radiomic Features in a Diverse Cohort of Patients With Pancreatic Ductal Adenocarcinomas.

BACKGROUND: Significant racial disparities in pancreatic cancer incidence and mortality rates exist, with the highest rates in African Americans compared to Non-Hispanic Whites and Hispanic/Latinx populations. Computer-derived quantitative imaging or "radiomic" features may serve as non-invasive surrogates for underlying biological factors and heterogeneity that characterize pancreatic tumors from African Americans, yet studies are lacking in this area. The objective of this pilot study was to determine if the radiomic tumor profile extracted from pretreatment computed tomography (CT) images differs between African Americans, Non-Hispanic Whites, and Hispanic/Latinx with pancreatic cancer. METHODS: We evaluated a retrospective cohort of 71 pancreatic cancer cases (23 African American, 33 Non-Hispanic White, and 15 Hispanic/Latinx) who underwent pretreatment CT imaging at Moffitt Cancer Center and Research Institute. Whole lesion semi-automated segmentation was performed on each slice of the lesion on all pretreatment venous phase CT exams using Healthmyne Software (Healthmyne, Madison, WI, USA) to generate a volume of interest. To reduce feature dimensionality, 135 highly relevant non-texture and texture features were extracted from each segmented lesion and analyzed for each volume of interest. RESULTS: Thirty features were identified and significantly associated with race/ethnicity based on Kruskal-Wallis test. Ten of the radiomic features were highly associated with race/ethnicity independent of tumor grade, including sphericity, volumetric mean Hounsfield units (HU), minimum HU, coefficient of variation HU, four gray level texture features, and two wavelet texture features. A radiomic signature summarized by the first principal component partially differentiated African American from non-African American tumors (area underneath the curve = 0.80). Poorer survival among African Americans compared to Non-African Americans was observed for tumors with lower volumetric mean CT [HR: 3.90 (95% CI:1.19-12.78), p=0.024], lower GLCM Avg Column Mean [HR:4.75 (95% CI: 1.44,15.37), p=0.010], and higher GLCM Cluster Tendency [HR:3.36 (95% CI: 1.06-10.68), p=0.040], and associations persisted in volumetric mean CT and GLCM Avg Column after adjustment for key clinicopathologic factors. CONCLUSIONS: This pilot study identified several textural radiomics features associated with poor overall survival among African Americans with PDAC, independent of other prognostic factors such as grade. Our findings suggest that CT radiomic features may serve as surrogates for underlying biological factors and add value in predicting clinical outcomes when integrated with other parameters in ongoing and future studies of cancer health disparities.

The Florida Pancreas Collaborative Next-Generation Biobank: Infrastructure to Reduce Disparities and Improve Survival for a Diverse Cohort of Patients with Pancreatic Cancer.

Background: Well-annotated, high-quality biorepositories provide a valuable platform to support translational research. However, most biorepositories have poor representation of minority groups, limiting the ability to address health disparities. Methods: We describe the establishment of the Florida Pancreas Collaborative (FPC), the first state-wide prospective cohort study and biorepository designed to address the higher burden of pancreatic cancer (PaCa) in African Americans (AA) compared to Non-Hispanic Whites (NHW) and Hispanic/Latinx (H/L). We provide an overview of stakeholders; study eligibility and design; recruitment strategies; standard operating procedures to collect, process, store, and transfer biospecimens, medical images, and data; our cloud-based data management platform; and progress regarding recruitment and biobanking. Results: The FPC consists of multidisciplinary teams from fifteen Florida medical institutions. From March 2019 through August 2020, 350 patients were assessed for eligibility, 323 met inclusion/exclusion criteria, and 305 (94%) enrolled, including 228 NHW, 30 AA, and 47 H/L, with 94%, 100%, and 94% participation rates, respectively. A high percentage of participants have donated blood (87%), pancreatic tumor tissue (41%), computed tomography scans (76%), and questionnaires (62%). Conclusions: This biorepository addresses a critical gap in PaCa research and has potential to advance translational studies intended to minimize disparities and reduce PaCa-related morbidity and mortality.

Multiphase computed tomography radiomics of pancreatic intraductal papillary mucinous neoplasms to predict malignancy.

BACKGROUND: Intraductal papillary mucinous neoplasms (IPMNs) are non-invasive pancreatic precursor lesions that can potentially develop into invasive pancreatic ductal adenocarcinoma. Currently, the International Consensus Guidelines (ICG) for IPMNs provides the basis for evaluating suspected IPMNs on computed tomography (CT) imaging. Despite using the ICG, it remains challenging to accurately predict whether IPMNs harbor high grade or invasive disease which would warrant surgical resection. A supplementary quantitative radiological tool, radiomics, may improve diagnostic accuracy of radiological evaluation of IPMNs. We hypothesized that using CT whole lesion radiomics features in conjunction with the ICG could improve the diagnostic accuracy of predicting IPMN histology. AIM: To evaluate whole lesion CT radiomic analysis of IPMNs for predicting malignant histology compared to International Consensus Guidelines. METHODS: Fifty-one subjects who had pancreatic surgical resection at our institution with histology demonstrating IPMN and available preoperative CT imaging were included in this retrospective cohort. Whole lesion semi-automated segmentation was performed on each preoperative CT using Healthmyne software (Healthmyne, Madison, WI). Thirty-nine relevant radiomic features were extracted from each lesion on each available contrast phase. Univariate analysis of the 39 radiomics features was performed for each contrast phase and values were compared between malignant and benign IPMN groups using logistic regression. Conventional quantitative and qualitative CT measurements were also compared between groups, via χ 2 (categorical) and Mann Whitney U (continuous) variables. RESULTS: Twenty-nine subjects (15 males, age 71 ± 9 years) with high grade or invasive tumor histology comprised the "malignant" cohort, while 22 subjects (11 males, age 70 ± 7 years) with low grade tumor histology were included in the "benign" cohort. Radiomic analysis showed 18/39 precontrast, 19/39 arterial phase, and 21/39 venous phase features differentiated malignant from benign IPMNs (P < 0.05). Multivariate analysis including only ICG criteria yielded two significant variables: thickened and enhancing cyst wall and enhancing mural nodule < 5 mm with an AUC (95%CI) of 0.817 (0.709-0.926). Multivariable post contrast radiomics achieved an AUC (95%CI) of 0.87 (0.767-0.974) for a model including arterial phase radiomics features and 0.834 (0.716-0.953) for a model including venous phase radiomics features. Combined multivariable model including conventional variables and arterial phase radiomics features achieved an AUC (95%CI) of 0.93 (0.85-1.0) with a 5-fold cross validation AUC of 0.90. CONCLUSION: Multi-phase CT radiomics evaluation could play a role in improving predictive capability in diagnosing malignancy in IPMNs. Future larger studies may help determine the clinical significance of our findings.

Repeatability of Quantitative Imaging Features in Prostate Magnetic Resonance Imaging.

Background: Multiparametric magnetic resonance imaging (mpMRI) has emerged as a non-invasive modality to diagnose and monitor prostate cancer. Quantitative metrics on the regions of abnormality have shown to be useful descriptors to discriminate clinically significant cancers. In this study, we evaluate the reproducibility of quantitative imaging features using repeated mpMRI on the same patients. Methods: We retrospectively obtained the deidentified records of patients, who underwent two mpMRI scans within 2 weeks of the first baseline scan. The patient records were obtained as deidentified data (including imaging), obtained through the TCIA (The Cancer Imaging Archive) repository and analyzed in our institution with an institutional review board-approved Health Insurance Portability and Accountability Act-compliant retrospective study protocol. Indicated biopsied regions were used as a marker for our study radiologists to delineate the regions of interest. We extracted 307 quantitative features in each mpMRI modality [T2-weighted MR sequence image (T2w) and apparent diffusion coefficient (ADC) with b values of 0 and 1,400 mm/s2] across the two sequential scans. Concordance correlation coefficients (CCCs) were computed on the features extracted from sequential scans. Redundant features were removed by computing the coefficient of determination (R 2) among them and replaced with a feature that had the highest dynamic range within intercorrelated groups. Results: We have assessed the reproducibility of quantitative imaging features among sequential scans and found that habitat region characterization improves repeatability in ADC maps. There were 19 T2w features and two ADC features in radiologist drawn regions (native raw image), compared to 18 T2w and 15 ADC features in habitat regions (sphere), which were reproducible (CCC ≥0.65) and non-redundant (R 2 ≥ 0.99). We also found that z-transformation of the images prior to feature extraction reduced the number of reproducible features with no detrimental effect. Conclusion: We have shown that there are quantitative imaging features that are reproducible across sequential prostate mpMRI acquisition at a preset level of filters. We also found that a habitat approach improves feature repeatability in ADC. A validated set of reproducible image features in mpMRI will allow us to develop clinically useful disease risk stratification, enabling the possibility of using imaging as a surrogate to invasive biopsies.

Racial and ethnic disparities in a state-wide registry of patients with pancreatic cancer and an exploratory investigation of cancer cachexia as a contributor to observed inequities.

Pancreatic cancer (PC) is characterized by racial/ethnic disparities and the debilitating muscle-wasting condition, cancer cachexia. Florida ranks second in the number of PC deaths and has a large and understudied minority population. We examined the primary hypothesis that PC incidence and mortality rates may be highest among Black Floridians and the secondary hypothesis that biological correlates of cancer cachexia may underlie disparities. PC incidence and mortality rates were estimated by race/ethnicity, gender, and county using publicly available state-wide cancer registry data that included approximately 2700 Black, 25 200 Non-Hispanic White (NHW), and 3300 Hispanic/Latino (H/L) Floridians diagnosed between 2004 and 2014. Blacks within Florida experienced a significantly (P < 0.05) higher incidence (12.5/100 000) and mortality (10.97/100 000) compared to NHW (incidence = 11.2/100 000; mortality = 10.3/100 000) and H/L (incidence = 9.6/100 000; mortality = 8.7/100 000), especially in rural counties. To investigate radiologic and blood-based correlates of cachexia, we leveraged data from a subset of patients evaluated at two geographically distinct Florida Cancer Centers. In Blacks compared to NHW matched on stage, markers of PC-induced cachexia were more frequent and included greater decreases in core musculature compared to corresponding healthy control patients (25.0% vs 10.1% lower), greater decreases in psoas musculature over time (10.5% vs 4.8% loss), lower baseline serum albumin levels (3.8 vs 4.0 gm/dL), and higher platelet counts (332.8 vs 268.7 k/UL). Together, these findings suggest for the first time that PC and cachexia may affect Blacks disproportionately. Given its nearly universal contribution to illness and PC-related deaths, the early diagnosis and treatment of cachexia may represent an avenue to improve health equity, quality of life, and survival.

In vivo positron emission tomographic blood pool imaging in an immunodeficient mouse model using 18F-fluorodeoxyglucose labeled human erythrocytes.

99m-Technetium-labeled (99mTc) erythrocyte imaging with planar scintigraphy is widely used for evaluating both patients with occult gastrointestinal bleeding and patients at risk for chemotherapy-induced cardiotoxicity. While a number of alternative radionuclide-based blood pool imaging agents have been proposed, none have yet to achieve widespread clinical use. Here, we present both in vitro and small animal in vivo imaging evidence that the high physiological expression of the glucose transporter GLUT1 on human erythrocytes allows uptake of the widely available radiotracer 2-deoxy-2-(18F)fluoro-D-glucose (FDG), at a rate and magnitude sufficient for clinical blood pool positron emission tomographic (PET) imaging. This imaging technique is likely to be amenable to rapid clinical translation, as it can be achieved using a simple FDG labeling protocol, requires a relatively small volume of phlebotomized blood, and can be completed within a relatively short time period. As modern PET scanners typically have much greater count detection sensitivities than that of commonly used clinical gamma scintigraphic cameras, FDG-labeled human erythrocyte PET imaging may not only have significant advantages over 99mTc-labeled erythrocyte imaging, but may have other novel blood pool imaging applications.

Imaging the Vasculature of Immunodeficient Mice Using Positron Emission Tomography/computed Tomography (PET/CT) and 18F-fluorodeoxyglucose Labeled Human Erythrocytes.

Nuclear blood pool imaging using radiolabeled red blood cells has been used in the clinical setting for the evaluation of a number of medical conditions including gastrointestinal hemorrhage, impaired cardiac contractility, and altered cerebrovascular blood flow. Nuclear blood pool imaging is typically performed using Technetium-99m-labeled (99mTc) human erythrocytes (i.e., the "tagged RBC" scan) and gamma camera-based planar scintigraphic imaging. When compared to typical clinical planar scintigraphy and single-photon emission computed tomographic (SPECT) imaging platforms, positron emission tomography (PET) provides superior image quality and sensitivity. A number of PET-based radionuclide agents have been proposed for blood pool imaging, but none have yet to be used widely in the clinical setting. In this protocol, we described a simple and fast procedure for imaging the vasculature of immunodeficient mice through a combination of a small animal positron emission tomography/computed tomography (PET/CT) scanner and human erythrocytes labeled with the PET tracer 2-deoxy-2-(18F)fluoro-D-glucose (18F-FDG). This technique is expected to have significant advantages over traditional 99mTc -labeled erythrocyte scintigraphic nuclear imaging for these reasons.

Linc-ing Circulating Long Non-coding RNAs to the Diagnosis and Malignant Prediction of Intraductal Papillary Mucinous Neoplasms of the Pancreas.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease that lacks effective biomarkers for early detection. We hypothesized that circulating long non-coding RNAs (lncRNAs) may act as diagnostic markers of incidentally-detected cystic PDAC precursors known as intraductal papillary mucinous neoplasms (IPMNs) and predictors of their pathology/histological classification. Using NanoString nCounter® technology, we measured the abundance of 28 candidate lncRNAs in pre-operative plasma from a cohort of pathologically-confirmed IPMN cases of various grades of severity and non-diseased controls. Results showed that two lncRNAs (GAS5 and SRA) aided in differentiating IPMNs from controls. An 8-lncRNA signature (including ADARB2-AS1, ANRIL, GLIS3-AS1, LINC00472, MEG3, PANDA, PVT1, and UCA1) had greater accuracy than standard clinical and radiologic features in distinguishing 'aggressive/malignant' IPMNs that warrant surgical removal from 'indolent/benign' IPMNs that can be observed. When the 8-lncRNA signature was combined with plasma miRNA data and quantitative 'radiomic' imaging features, the accuracy of predicting IPMN pathological classification improved. Our findings provide novel information on the ability to detect lncRNAs in plasma from patients with IPMNs and suggest that an lncRNA-based blood test may have utility as a diagnostic adjunct for identifying IPMNs and their pathology, especially when incorporated with biomarkers such as miRNAs, quantitative imaging features, and clinical data.

A pilot study of radiologic measures of abdominal adiposity: weighty contributors to early pancreatic carcinogenesis worth evaluating?

OBJECTIVE: Intra-abdominal fat is a risk factor for pancreatic cancer (PC), but little is known about its contribution to PC precursors known as intraductal papillary mucinous neoplasms (IPMNs). Our goal was to evaluate quantitative radiologic measures of abdominal/visceral obesity as possible diagnostic markers of IPMN severity/pathology. METHODS: In a cohort of 34 surgically-resected, pathologically-confirmed IPMNs (17 benign; 17 malignant) with preoperative abdominal computed tomography (CT) images, we calculated body mass index (BMI) and four radiologic measures of obesity: total abdominal fat (TAF) area, visceral fat area (VFA), subcutaneous fat area (SFA), and visceral to subcutaneous fat ratio (V/S). Measures were compared between groups using Wilcoxon two-sample exact tests and other metrics. RESULTS: Mean BMI for individuals with malignant IPMNs (28.9 kg/m2) was higher than mean BMI for those with benign IPMNs (25.8 kg/m2) (P=0.045). Mean VFA was higher for patients with malignant IPMNs (199.3 cm2) compared to benign IPMNs (120.4 cm2),P=0.092. V/S was significantly higher (P=0.013) for patients with malignant versus benign IPMNs (1.25vs. 0.69 cm2), especially among females. The accuracy, sensitivity, specificity, and positive and negative predictive value of V/S in predicting malignant IPMN pathology were 74%, 71%, 76%, 75%, and 72%, respectively. CONCLUSIONS: Preliminary findings suggest measures of visceral fat from routine medical images may help predict IPMN pathology, acting as potential noninvasive diagnostic adjuncts for management and targets for intervention that may be more biologically-relevant than BMI. Further investigation of gender-specific associations in larger, prospective IPMN cohorts is warranted to validate and expand upon these observations.

CT findings associated with blastic plasmacytoid dendritic cell neoplasm: a case report.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy that is frequently misdiagnosed. We present a case of a 53-year-old man diagnosed with blastic plasmacytoid dendritic cell neoplasm with extensive computed tomography (CT) findings and provide an imaging focused review of this uncommon malignancy.

Non-infectious cholecystopathy secondary to high-dose IL-2 cancer immunotherapy.

Interleukin-2 (IL-2) associated cholecystopathy is a rare manifestation of IL-2 drug toxicity in the setting of cancer immunotherapy. While the imaging data and clinical presentation can easily mimic acute cholecystitis, the correct diagnosis can be made with the particular clinical history, thus avoiding inappropriate surgical management. As more cancer immunotherapies become standard oncologic treatments, specific immunotherapy-associated side effects are also expected to be encountered more frequently in the future and should be recognized as such. We present a case of IL-2-associated cholecystopathy in the setting of renal cell carcinoma immunotherapy.

Intravenous Imaging Contrast Media Complications: The Basics That Every Clinician Needs to Know.

Intravenous contrast is commonly used in noninvasive imaging procedures such as magnetic resonance imaging and computed tomography and can evaluate blood vessels and better characterize soft-tissue lesions. Although the incidence of adverse events after administration of contrast is low, it is important that clinicians and radiologists minimize risks and respond quickly and effectively when reactions occur. We will discuss a range of adverse events to iodinated and gadolinium-based contrast agents, including allergic-like reactions, nephrotoxicity, extravasation, and nephrogenic systemic fibrosis. We will review risk stratification for patients, as well as premedication and treatment of adverse events.

Mean apparent diffusion coefficient values in defining radiotherapy planning target volumes in glioblastoma.

BACKGROUND: To evaluate mean apparent diffusion coefficient (ADC) values on pre-radiotherapy magnetic resonance (MR) at sites that gave rise to glioblastoma (GBM) recurrence compared to similar surrounding background tissue that did not progress to tumor. METHODS: Twenty out of 110 consecutive patients with pathology proven GBM treated at our institution from 1/1/2009 to 5/31/2012 had definitive recurrence 6 months following radiotherapy. In this single-center retrospective cohort study, pre- and post-radiotherapy MR brain exams were evaluated. Sites of tumor recurrence on post-therapy exams were co-localized to pre-therapy exams and the background tissue type which gave rise to tumor was noted (i.e., T2 hyperintensity, normal appearing white or gray matter). Similar surrounding background tissue not progressing to tumor was also selected. Two radiologists compared mean ADC values on pre-radiotherapy MR for sites which gave rise to future tumor recurrence and sites of similar background tissue. RESULTS: Pre-radiotherapy mean ADC values were significantly lower in regions of future tumor recurrence than in regions of surrounding background tissue not progressing to tumor (P=0.003). There were no significant quantitative differences on T1-weighted pre contrast (P=0.50) or T2-weighted (P=0.10) sequences between sites. There was strong interobserver agreement with an intraclass correlation of 0.867 for ADC values at sites of future tumor recurrence and background tissue. CONCLUSIONS: Mean ADC values may help predict sites of future gross tumor recurrence in GBM, which could be helpful in radiation therapy planning.

Real-time ultrasound-guided needle injection of the mouse jugular vein.

This unit describes a novel method for direct venous injection into mice that offers potentially significant advantages over commonly used mouse vein injection techniques. This is achieved via percutaneous needle placement into the mouse jugular vein under real-time B-mode ultrasound (US) imaging. Real-time US imaging of the injection process allows for immediate determination of the overall success of injection. Unique, and potentially significant, advantages of this technique over others include: (1) direct visual confirmation of needle tip placement in the lumen of the vein, (2) immediate visual detection of extravascular extravasation of injectate, when compared to blinded techniques, such as tail vein injections, and (3) reduced morbidity and mortality compared to surgical vascular access techniques (i.e., jugular vein cannulation). This technique may lead to more accurate determination of the success of the injection procedure for each mouse, thus improving the quality of acquired data in dependent mouse experiments.

Single-cell detection of trans-splicing ribozyme in vivo activity.

The Tetrahymena trans-splicing ribozyme can edit RNA in a sequence-specific manner, but its efficiency needs to be improved for any functional rescues. This communication describes a simple method that uses a bacterial enzyme beta-lactamase to report trans-splicing activity of Tetrahymena ribozyme in single living mammalian cells by fluorescence microscopy and flow cytometry. This enzyme-based single-cell detection method is highly sensitive and compatible with living cell flow cytometry, and should allow a cell-based systematic screening of a vast library of ribozymes for better trans-spliced ribozyme variants.