3D pCASL-perfusion in preoperative assessment of brain gliomas in large cohort of patients.

The aim of the study was to evaluate the role of pseudocontinuous arterial spin labeling perfusion (pCASL-perfusion) in preoperative assessment of cerebral glioma grades. The study group consisted of 253 patients, aged 7-78 years with supratentorial gliomas (65 low-grade gliomas (LGG), 188 high-grade gliomas (HGG)). We used 3D pCASL-perfusion for each patient in order to calculate the tumor blood flow (TBF). We obtained maximal tumor blood flow (maxTBF) in small regions of interest (30 ± 10 mm2) and then normalized absolute maximum tumor blood flow (nTBF) to that of the contralateral normal-appearing white matter of the centrum semiovale. MaxTBF and nTBF values significantly differed between HGG and LGG groups (p < 0.001), as well as between patient groups separated by the grades (grade II vs. grade III) (p < 0.001). Moreover, we performed ROC-analysis which demonstrated high sensitivity and specificity in differentiating between HGG and LGG. We found significant differences for maxTBF and nTBF between grade III and IV gliomas, however, ROC-analysis showed low sensitivity and specificity. We did not observe a significant difference in TBF for astrocytomas and oligodendrogliomas. Our study demonstrates that 3D pCASL-perfusion as an effective diagnostic tool for preoperative differentiation of glioma grades.

Referring Physicians Assess the Quality of Outpatient Diagnostic Imaging Services: Development and Psychometric Evaluation of a Questionnaire.

GOAL: In order to ensure high-quality cooperation between referring physicians and imaging services, it is important to assess the quality of imaging services as perceived by referring physicians. The present study aimed to develop and validate a questionnaire for referring physicians to assess the quality of outpatient diagnostic imaging services. MATERIALS & METHODS: The questionnaire was developed by discussing and modifying an existing instrument by the German Association of Surgeons. After qualitative pretesting, the instrument was tested with physicians referring to four outpatient diagnostic imaging services in Switzerland. The results were first assessed using descriptive statistics. The final instrument was tested for validity using the concept of known-groups validity. The hypothesis underlying this procedure was that physicians referring frequently to services estimated the quality of these services to be higher than physicians who referred less often to services. The differences in ratings were assessed using a one-sided two-sample Wilcoxon test. The final questionnaire was tested for internal consistency and reliability using Cronbach's Alpha. RESULTS: Results show a high level of satisfaction of referring physicians with the relevant services but also potential for quality improvement initiatives. The psychometric evaluation of the final questionnaire shows that it is a valid instrument, showing significant differences between the ratings of physicians referring with high and low frequency. Furthermore, the instrument proves to be consistent and reliable. CONCLUSION: The final instrument presents a valid, consistent and reliable option for assess the quality of outpatient diagnostic imaging services as perceived by referring physicians. Results can be used as a basis for quality improvement. KEY POINTS: · A newly developed questionnaire assesses the quality of outpatient diagnostic imaging services as perceived by referring physicians. The questionnaire was developed and tested in Switzerland.. · Psychometric evaluation showed the questionnaire to be a valid, consistent and reliable instrument.. · Results are of interest for imaging services as well as for initiatives encompassing several services.. CITATION FORMAT: · Jossen M, Valeri F, Heilmaier C et al. Referring Physicians Assess the Quality of Outpatient Diagnostic Imaging Services: Development and Psychometric Evaluation of a Questionnaire. Fortschr Röntgenstr 2019; 191: 725 - 731.

Optical techniques for perfusion monitoring of the gastric tube after esophagectomy: a review of technologies and thresholds.

Anastomotic leakage is one of the most severe complications after esophageal resection with gastric tube reconstruction. Impaired perfusion of the gastric fundus is seen as the main contributing factor for this complication. Optical modalities show potential in recognizing compromised perfusion in real time, when ischemia is still reversible. This review provides an overview of optical techniques with the aim to evaluate the (1) quantitative measurement of change in perfusion in gastric tube reconstruction and (2) to test which parameters are the most predictive for anastomotic leakage.A Pubmed, MEDLINE, and Embase search was performed and articles on laser Doppler flowmetry (LDF), near-infrared spectroscopy (NIRS), laser speckle contrast imaging (LSCI), fluorescence imaging (FI), sidestream darkfield microscopy (SDF), and optical coherence tomography (OCT) regarding blood flow in gastric tube surgery were reviewed. Two independent reviewers critically appraised articles and extracted the data: Primary outcome was quantitative measure of perfusion change; secondary outcome was successful prediction of necrosis or anastomotic leakage by measured perfusion parameters.Thirty-three articles (including 973 patients and 73 animals) were selected for data extraction, quality assessment, and risk of bias (QUADAS-2). LDF, NIRS, LSCI, and FI were investigated in gastric tube surgery; all had a medium level of evidence. IDEAL stage ranges from 1 to 3. Most articles were found on LDF (n = 12), which is able to measure perfusion in arbitrary perfusion units with a significant lower amount in tissue with necrosis development and on FI (n = 12). With FI blood flow routes could be observed and flow was qualitative evaluated in rapid, slow, or low flow. NIRS uses mucosal oxygen saturation and hemoglobin concentration as perfusion parameters. With LSCI, a decrease of perfusion units is observed toward the gastric fundus intraoperatively. The perfusion units (LDF, LSCI), although arbitrary and not absolute values, and low flow or length of demarcation to the anastomosis (FI) both seem predictive values for necrosis intraoperatively. SDF and OCT are able to measure microvascular flow, intraoperative prediction of necrosis is not yet described.Optical techniques aim to improve perfusion monitoring by real-time, high-resolution, and high-contrast measurements and could therefore be valuable in intraoperative perfusion mapping. LDF and LSCI use perfusion units, and are therefore subjective in interpretation. FI visualizes influx directly, but needs a quantitative parameter for interpretation during surgery.

[Role of quantitative perfusion scintigraphy evaluation in determination of the efficiency of the procedure before lung volume reduction coil treatment for severe emphysema]. / Agir amfizem için hacim azaltici sarmal tedavisi öncesi kantitatif perfüzyon sintigrafisi degerlendirmesinin islemin etkinligini belirlemedeki rolü.

INTRODUCTION: Lung volume reduction coil (LVRC) is a new treatment method which exercise capacities among the patients with severe emphysema. In order to determine the emphysema distribution before LVRC treatment, we examined the contribution of combination of the high resolution computed tomography (HRCT) of the lung and the quantitative perfusion scintigraphy to the efficiency of the procedure. MATERIALS AND METHODS: The study was conducted retrospectively. The densitometry analysis and scores of emphysema areas of the patients who were found suitable for LVRC treatment in HRCT were determined. Before the procedure, the quantitative lung perfusion scintigraphies were taken. Lobes which had high emphysema score and in which a decrease perfusion was observed in quantitative perfusion scintigraphy were determined as treatment areas. RESULT: A total of 22 patients were treated. In HRCT it was observed that perfusion decreased in lobes in which the emphysema damage scoring was high. A significant statistical difference was found between pre-and post- procedure measurements in terms of FEV1, RV, and TLC (p<0.05). In six minute walk test, a statistically significant difference was found as 45.4 ± 23.9 m (p= 0.000). No significant difference was determined between perfusion ratios before the procedure and perfusion ratios after the procedure. CONCLUSIONS: The quantitative perfusion scintigraphy taken before LVRC treatment in severe emphysema patients guides to determine the target lobe for treatment and makes contribution to the efficiency of the procedure.

Utility of perfusion imaging in acute stroke treatment: a systematic review and meta-analysis.

BACKGROUND: Variability in imaging protocols and techniques has resulted in a lack of consensus regarding the incorporation of perfusion imaging into stroke triage and treatment. The objective of our study was to evaluate the available scientific evidence regarding the utility of perfusion imaging in determining treatment eligibility in patients with acute stroke and in predicting their clinical outcome. METHODS: We performed a systematic review of the literature using PubMed, Web of Science, and Cochrane Library focusing on themes of medical imaging, stroke, treatment, and outcome (CRD42016037817). We included randomized controlled trials, cohort studies, and case-controlled studies published from 2011 to 2016. Two independent reviewers conducted the study appraisal, data abstraction, and quality assessments of the studies. RESULTS: Our literature search yielded 13 studies that met our inclusion criteria. In total, 994 patients were treated with the aid of perfusion imaging compared with 1819 patients treated with standard care. In the intervention group 51.1% of patients had a favorable outcome at 3 months compared with 45.6% of patients in the control group (p=0.06). Subgroup analysis of studies that used multimodal therapy (IV tissue plasminogen activator, endovascular thrombectomy) showed a significant benefit of perfusion imaging (OR 1.89, 95% CI 1.43 to 2.51, p<0.01). CONCLUSIONS: Perfusion imaging may represent a complementary tool to standard radiographic assessment in enhancing patient selection for reperfusion therapy, with a subset of patients having up to 1.9 times the odds of achieving independent functional status at 3 months. This is particularly important as patients selected based on perfusion status often included individuals who did not meet the current treatment eligibility criteria.

Utilization of MR angiography in perfusion imaging for identifying arterial input function.

OBJECTIVE: This research utilizes magnetic resonance angiography (MRA) to identify arterial locations during the parametric evaluation of concentration time curves (CTCs), and to prevent shape distortions in arterial input function (AIF). MATERIALS AND METHODS: We carried out cluster analysis with the CTC parameters of voxels located within and around the middle cerebral artery (MCA). Through MRA, we located voxels that meet the AIF criteria and those with distorted CTCs. To minimize partial volume effect, we re-scaled the time integral of CTCs by the time integral of venous output function (VOF). We calculated the steady-state value to area under curve ratio (SS:AUC) of VOF and used it as a reference in selecting AIF. CTCs close to this reference value (selected AIF) and those far from it were used (eliminated AIF) to compute cerebral blood flow (CBF). RESULTS: Eliminated AIFs were found to be either on or anterior to MCA, whereas selected AIFs were located superior, inferior, posterior, or anterior to MCA. If the SS:AUC of AIF was far from the reference value, CBF was either under- or over-estimated by a maximum of 41.1 ± 14.3 and 36.6 ± 19.2%, respectively. CONCLUSION: MRA enables excluding voxels on the MCA during cluster analysis, and avoiding the risk of shape distortions.

Learning of speckle statistics for in vivo and noninvasive characterization of cutaneous wound regions using laser speckle contrast imaging.

Laser speckle contrast imaging (LSCI) provides a noninvasive and cost effective solution for in vivo monitoring of blood flow. So far, most of the researches consider changes in speckle pattern (i.e. correlation time of speckle intensity fluctuation), account for relative change in blood flow during abnormal conditions. This paper introduces an application of LSCI for monitoring wound progression and characterization of cutaneous wound regions on mice model. Speckle images are captured on a tumor wound region at mice leg in periodic interval. Initially, raw speckle images are converted to their corresponding contrast images. Functional characterization begins with first segmenting the affected area using k-means clustering, taking wavelet energies in a local region as feature set. In the next stage, different regions in wound bed are clustered based on progressive and non-progressive nature of tissue properties. Changes in contrast due to heterogeneity in tissue structure and functionality are modeled using LSCI speckle statistics. Final characterization is achieved through supervised learning of these speckle statistics using support vector machine. On cross evaluation with mice model experiment, the proposed approach classifies the progressive and non-progressive wound regions with an average sensitivity of 96.18%, 97.62% and average specificity of 97.24%, 96.42% respectively. The clinical information yield with this approach is validated with the conventional immunohistochemistry result of wound to justify the ability of LSCI for in vivo, noninvasive and periodic assessment of wounds.

[Total liver CT perfusion imaging for evaluation on rabbit liver VX2 tumor perfusion and comparative analysis through immunohistochemisty].

OBJECTIVE: To investigate the correlations among total liver CT perfusion parameters, unpaired arteries (UAs) and microvessel area (MVA) in a rabbit liver VX2 tumor model, and to learn the tumoral angiogenesis condition and the mechanisms for perfusion imaging.
 Methods: Rabbits with or without the inoculated VX2 tumor in the liver underwent total liver CT perfusion imaging 2 weeks after the operation. Perfusion parameters included blood flow (BF), blood volume (BV), arterial liver perfusion (ALP), portal liver perfusion (PVP), hepatic perfusion index (HPI) for the tumor rim and the surrounding liver tissue. After the examination, the UAs and MVA of tumor tissues were obtained by immunohistochemical staining. The differences of perfusion parameters between the vital tumor rim and the surrounding liver tissue were compared. The correlations among perfusion parameters, UAs and MVA were analyzed.
 Results: There was significant difference between the CT perfusion parameters at the tumor rim and the surrounding liver tissue or liver tissue of the control group (P<0.05), but there was no significant difference between the perfusion parameters at the surrounding liver tissues of the experimental group and the control (P>0.05). There was positive correlation between UAs and MVA. UAs and MVA were positively correlated with BF, ALP and BV at the tumor rim. UAs and MVA were negatively correlated with PVP. HPI positively correlated with UAs, but it was not correlated with MVA.
 Conclusion: Total liver CT perfusion can provide quantitative information to evaluate the artery and portal vein perfusion of liver VX2 tumor, and to assess the degree of tumor angiogenesis.

Dynamic volume perfusion CT in patients with lung cancer: baseline perfusion characteristics of different histological subtypes.

OBJECTIVE: To evaluate dynamic volume perfusion CT (dVPCT) tumor baseline characteristics of three different subtypes of lung cancer in untreated patients. MATERIALS AND METHODS: 173 consecutive patients (131 men, 42 women; mean age 61 ± 10 years) with newly diagnosed lung cancer underwent dVPCT prior to biopsy. Tumor permeability, blood flow (BF), blood volume (BV) and mean transit time (MTT) were quantitatively assessed as well as tumor diameter and volume. Tumor subtypes were histologically determined and compared concerning their dVPCT results. dVPCT results were correlated to tumor diameter and volume. RESULTS: Histology revealed adenocarcinoma in 88, squamous cell carcinoma in 54 and small cell lung cancer (SCLC) in 31 patients. Tumor permeability was significantly differing between adenocarcinoma, squamous cell carcinoma and SCLC (all p<0.05). Tumor BF and BV were higher in adenocarcinomathan in SCLC (p = 0.001 and p=0.0002 respectively). BV was also higher in squamous cell carcinoma compared to SCLC (p = 0.01). MTT was not differing between tumor subtypes. Regarding all tumors, tumor diameter did not correlate with any of the dVPCT parameters, whereas tumor volume was negatively associated with permeability, BF and BV (r = -0.22, -0.24, -0.24, all p<0.05). In squamous cell carcinoma, tumor diameter und volume correlated with BV (r = 0.53 and r = -0.40, all p<0.05). In SCLC, tumor diameter und volume correlated with MTT (r = 0.46 and r = 0.39, all p<0.05). In adenocarcinoma, no association between morphological and functional tumor characteristics was observed. CONCLUSIONS: dVPCT parameters are only partially related to tumor diameter and volume and are significantly differing between lung cancer subtypes.

Can we justify not doing liver perfusion imaging in 2013?

Liver perfusion imaging is a quantitative functional investigation. Liver perfusion imaging is complicated because of the liver's dual vascular supply, artefacts due to respiratory movements and the fenestrated sinusoidal capillaries which allow the contrast medium to diffuse out. Liver perfusion can be examined by ultrasound, CT or MRI: each technique has its limitations and specific features. The major indications in hepatology are oncology (detection, characterization and tumor response) and non-invasive investigation of patients with chronic liver disease. Work is needed to standardize acquisition and modeling methods to allow wider use of results and more widespread use of the technique.

Perfusion heterogeneity in breast tumors for assessment of angiogenesis.

OBJECTIVES: The purpose of this study was to investigate the perfusion heterogeneity of malignant and benign breast tumors and assay their vascular architecture changes and molecular expression, thereby evaluating the relevance between imaging and histologic characteristics of angiogenesis. METHODS: Real-time grayscale contrast-enhanced sonography was performed in 310 women with 317 breast tumors. The enhancement patterns and perfusion parameters for malignant and benign tumors were analyzed by contrast-enhanced sonography with microvascular imaging and quantitative time-intensity curve analysis. Structural characteristics were observed by light and electron microscopy. The microvessel density, vascular endothelial growth factor (VEGF) expression, and human kinase insert domain-containing receptor (KDR) expression for all tumors were assessed by immunohistochemical staining of CD31, KDR, and VEGF. RESULTS: Surgical pathologic analysis showed 163 malignant and 154 benign tumors. Significant morphologic differences, including perfusion defects, vessel distortion, vessel dilatation, and heterogeneous enhancement, were observed between the malignant and benign groups (P < .05). The mean perfusion parameters (peak intensity, ascending slope, area under the curve, and wash-out time) were greater in the malignant tumors (P < .05). There were significant differences in the peak intensity, ascending slope, area under the curve, and wash-out time between peripheral and central regions of the malignant tumors (P < .05) but none in the benign tumors. Vessels had various morphologic and distributional characteristics in the peripheral and central regions of the malignant tumors. The microvessel density and VEGF and KDR expression were significantly higher in the malignant group (P < .05), especially in the peripheral regions. CONCLUSIONS: Perfusion heterogeneity was closely associated with the tumor microvascular architecture and molecular expression. Perfusion features, especially regional morphologic and hemodynamic features, can provide valuable information for differentiating malignant from benign breast tumors.

Analysis of perfusion defects by causes other than acute pulmonary thromboembolism on contrast-enhanced dual-energy CT in consecutive 537 patients.

OBJECTIVE: To assess causes, incidence and patterns of perfusion defects (PDs) on dual-energy perfusion CT angiography (DECTA) in clinically suspected acute pulmonary thromboembolisms (PTE). MATERIALS AND METHODS: Consecutive 537 patients who underwent DECTA for suspicion of PTE were retrospectively reviewed. After excluding patients with possible PTE or unsatisfactory perfusion map quality, 299 patients with 1697 lobes were included. The DECTA (Somatom Definition, Siemens) was performed at 140kV and 80kV. Color-coded perfusion images were obtained with a lung PBV application of the workstation software (Syngo Dual Energy). The presence, incidence, three patterns of PDs (wedge-shaped, heterogeneous, and regionally homogeneous), pulmonary diseases, and the matchedness between the PD and the disease extent were studied. RESULTS: 315 of 1697 lobes (18.6%) in 156 of 299 patients (81.3%) showed PDs. Among them, 51 (3%), 257 (15.1%), and 7 (0.4%) lobes had PDs due to vascular, nonvascular, and unidentifiable causes, respectively. Vascular causes include: pulmonary arterial (PA) hypertension (0.7%), extrinsic occlusion of PA by fibrosis (0.6%), PA hypoplasia (0.6%), vasculitis (0.5%), cancer mass compressing PA, venous occlusion, AVM, and pulmonary angiosarcoma. Most of PDs were wedge-shaped and well-matched. Nonvascular causes include: mosaic attenuation (4.1%), emphysema (3.2%), interstitial fibrosis (1.6%), bronchitis (1.4%), GGO (1.2%), cellular bronchiolitis (1%), bronchiectasis, airway obstruction, compensaroty lung hyperinflation, air trapping, cor-pulmonale, bronchopneumonia, physiologic decreased ventilation, and segmental bronchial atresia. Most of PDs showed heterogeneous pattern and were not matched. CONCLUSIONS: Various vascular and nonvascular diseases cause PDs on DECTA. Each disease shows different pattern of PD depending on pathophysiology and physiologic compensation.

The current state of practice in the diagnosis of venous thromboembolism at an academic medical center.

Evidence-based guidelines for the diagnosis of venous thromboembolism (VTE) have been recommended, yet the adoption of such guidelines into daily practice is unknown. The purpose of this study was to describe the current practices in the diagnosis of VTE. Medical records of 1161 adult patients who underwent lower extremity venous duplex scans (VDS), chest computerized tomographic (CT) angiography, or ventilation and perfusion (V/Q) scans during a 6-month period were retrospectively reviewed in an academic medical center. Patients who were first diagnosed by CT or V/Q scan still underwent a VDS. Nine patients at high risk had incomplete CT scans, yet no further tests were performed. Five pregnant patients had CT scans as the initial test instead of being screened with VDS or V/Q scanning. Inappropriate use of imaging tests was documented. The recommended guidelines of using clinical probability and D-dimer as the initial screening tests for VTE diagnosis were underused.

State-of-the-art radiological techniques improve the assessment of postoperative lung function in patients with non-small cell lung cancer.

PURPOSE: The purpose of this study was to compare predictive capabilities for postoperative lung function in non-small cell lung cancer (NSCLC) patients of the state-of-the-art radiological methods including perfusion MRI, quantitative CT and SPECT/CT with that of anatomical method (i.e. qualitative CT) and traditional nuclear medicine methods such as planar imaging and SPECT. MATERIALS AND METHODS: Perfusion MRI, CT, nuclear medicine study and measurements of %FEV(1) before and after lung resection were performed for 229 NSCLC patients (125 men and 104 women). For perfusion MRI, postoperative %FEV(1) (po%FEV(1)) was predicted from semi-quantitatively assessed blood volumes within total and resected lungs, for quantitative CT, it was predicted from the functional lung volumes within total and resected lungs, for qualitative CT, from the number of segments of total and resected lungs, and for nuclear medicine studies, from uptakes within total and resected lungs. All SPECTs were automatically co-registered with CTs for preparation of SPECT/CTs. Predicted po%FEV(1)s were then correlated with actual po%FEV(1)s, which were measured %FEV(1)s after operation. The limits of agreement were also evaluated. RESULTS: All predicted po%FEV(1)s showed good correlation with actual po%FEV(1)s (0.83≤r≤0.88, p<0.0001). Perfusion MRI, quantitative CT and SPECT/CT demonstrated better correlation than other methods. The limits of agreement of perfusion MRI (4.4±14.2%), quantitative CT (4.7±14.2%) and SPECT/CT (5.1±14.7%) were less than those of qualitative CT (6.0±17.4%), planar imaging (5.8±18.2%), and SPECT (5.5±16.8%). CONCLUSIONS: State-of-the-art radiological methods can predict postoperative lung function in NSCLC patients more accurately than traditional methods.