Liver Imaging Reporting and Data System Contrast-Enhanced US Nonradiation Treatment Response Assessment Version 2024.

The American College of Radiology Liver Imaging Reporting and Data System (LI-RADS) standardizes the imaging technique, reporting lexicon, disease categorization, and management for patients with or at risk for hepatocellular carcinoma (HCC). LI-RADS encompasses HCC surveillance with US; HCC diagnosis with CT, MRI, or contrast-enhanced US (CEUS); and treatment response assessment (TRA) with CT or MRI. LI-RADS was recently expanded to include CEUS TRA after nonradiation locoregional therapy or surgical resection. This report provides an overview of LI-RADS CEUS Nonradiation TRA v2024, including a lexicon of imaging findings, techniques, and imaging criteria for posttreatment tumor viability assessment. LI-RADS CEUS Nonradiation TRA v2024 takes into consideration differences in the CEUS appearance of viable tumor and posttreatment changes within and in close proximity to a treated lesion. Due to the high sensitivity of CEUS to vascular flow, posttreatment reactive changes commonly manifest as areas of abnormal perilesional enhancement without washout, especially in the first 3 months after treatment. To improve the accuracy of CEUS for nonradiation TRA, different diagnostic criteria are used to evaluate tumor viability within and outside of the treated lesion margin. Broader criteria for intralesional enhancement increase sensitivity for tumor viability detection. Stricter criteria for perilesional enhancement limit miscategorization of posttreatment reactive changes as viable tumor. Finally, the TRA algorithm reconciles intralesional and perilesional tumor viability assessment and assigns a single LI-RADS treatment response (LR-TR) category: LR-TR nonviable, LR-TR equivocal, or LR-TR viable.

New Technologies in the Assessment of Carotid Stenosis: Beyond the Color-Doppler Ultrasound-High Frame Rate Vector-Flow and 3D Arterial Analysis Ultrasound.

Atherosclerotic plaque in the carotid artery is the main cause of ischemic stroke, with a high incidence rate among people over 65 years. A timely and precise diagnosis can help to prevent the ischemic event and decide patient management, such as follow up, medical, or surgical treatment. Presently, diagnostic imaging techniques available include color-Doppler ultrasound, as a first evaluation technique, computed tomography angiography, which, however, uses ionizing radiation, magnetic resonance angiography, still not in widespread use, and cerebral angiography, which is an invasively procedure reserved for therapeutically purposes. Contrast-enhanced ultrasound is carving out an important and emerging role which can significantly improve the diagnostic accuracy of an ultrasound. Modern ultrasound technologies, still not universally utilized, are opening new horizons in the arterial pathologies research field. In this paper, the technical development of various carotid artery stenosis diagnostic imaging modalities and their impact on clinical efficacy is thoroughly reviewed.

Clinical, ocular motor, and imaging profile of Niemann-Pick type C heterozygosity.

OBJECTIVE: To characterize subclinical abnormalities in asymptomatic heterozygote NPC1 mutation carriers as markers of neurodegeneration. METHODS: Motor function, cognition, mood, sleep, and smell function were assessed in 20 first-degree heterozygous relatives of patients with Niemann-Pick disease type C (NPC) (13 male, age 52.7 ± 9.9 years). Video-oculography and abdominal ultrasound with volumetry were performed to assess oculomotor function and size of liver and spleen. NPC biomarkers in blood were analyzed. 18F-fluorodesoxyglucose PET was performed (n = 16) to detect patterns of brain hypometabolism. RESULTS: NPC heterozygotes recapitulated characteristic features of symptomatic NPC disease and demonstrated the oculomotor abnormalities typical of NPC. Hepatosplenomegaly (71%) and increased cholestantriol (33%) and plasma chitotriosidase (17%) levels were present. The patients also showed signs seen in other neurodegenerative diseases, including hyposmia (20%) or pathologic screening for REM sleep behavior disorder (24%). Cognitive function was frequently impaired, especially affecting visuoconstructive function, verbal fluency, and executive function. PET imaging revealed significantly decreased glucose metabolic rates in 50% of participants, affecting cerebellar, anterior cingulate, parieto-occipital, and temporal regions, including 1 with bilateral abnormalities. CONCLUSION: NPC heterozygosity, which has a carrier frequency of 1:200 in the general population, is associated with abnormal brain metabolism and functional consequences. Clinically silent heterozygous gene variations in NPC1 may be a risk factor for late-onset neurodegeneration, similar to the concept of heterozygous GBA mutations underlying Parkinson disease.

VTIQ and VTQ in combination with B-mode and color Doppler ultrasound improve classification of salivary gland tumors, especially for inexperienced physicians.

BACKGROUND: Ultrasound is the method of choice for preoperative evaluation of masses of the parotid glands. However, existing methods do not allow for definite differentiation between the most common benign and malignant tumors. OBJECTIVE: Thus, we evaluated the benefits of Virtual Touch Quantification (VTQ) and Virtual Touch imaging quantification (VTIQ) for improving preoperative evaluation of parotid tumors. METHODS: We investigated eight lymph nodes and 41 tumors of the parotid gland via ultrasound, color Doppler ultrasound, VTIQ and VTQ shear wave imaging. Each examination consisted of pictures and videos, which were evaluated by twelve examiners. Initially, each examiner predicted whether the mass was benign or malignant based on B-mode and Doppler images. Then each examiner viewed the VTIQ and VTQ shear wave images and reevaluated the predictions, which were then compared with the histopathological outcomes. RESULTS: In tumors, the sensitivity was 36% based only on B-mode and color Doppler sonography, which increased to 42% with the addition of VTIQ and VTQ. Likewise, the specificity also increased from 78% to 85%. CONCLUSIONS: VTQ and VTIQ provide additional data that improve the capability to distinguish between benign and malignant tumors allowing for an increase in both the sensitivity and specificity.

Does acoustic radiation force elastography improve the diagnostic capability of ultrasound in the preoperative characterization of masses of the parotid gland?

OBJECTIVES:: Ultrasound is the method of choice for preoperative evaluation of tumours of the parotid glands. However, existing methods do not allow for clear differentiation between the most common benign tumours and malignant tumours. The aim of our study was to evaluate if acoustic radiation force, Virtual Touch Quantification (VTQ) elastography helps to improve the preoperative evaluation of parotid masses. METHODS:: We investigated the parenchyma of 102 parotid glands, 14 lymph nodes of healthy volunteers and 51 tumours of the parotid gland via ultrasound, colour Doppler ultrasound and VTQ. The results were matched with histopathology and analyzed. RESULTS:: The perfusion in pleomorphic adenoma, the most frequent benign tumour of the parotid gland, was significantly lower in comparison to malignant tumours. All tumours showed statistically significant higher perfusion in comparison to the parenchyma or the lymph nodes of the gland. Shear wave velocity of the user-defined region of interest was statistically significant more frequently an overflow value higher than 8.5 m/s in total tumours in comparison to parenchyma or lymph nodes. The different tumour types presented no significant difference in the shear wave velocity. CONCLUSIONS:: VTQ in combination with classical ultrasound examination provides additional data useful in distinguishing between benign and malignant tumours and thus shows promise for integration into preexisting ultrasound protocols. However, despite the improvement, clear differentiation of tumours is still not possible and further investigation is recommended.

Dynamic CTA in Native Kidneys Using a Multiphase CT Protocol-Potential of Significant Reduction of Contrast Medium.

RATIONALE AND OBJECTIVE: The objective of this study was to assess an optimized renal multiphase computed tomography angiography (MP-CTA) protocol regarding reduction of contrast volume. MATERIALS AND METHODS: Thirty patients underwent MP-CTA (12 phases, every 3.5 seconds, 80 kV/120 mAs) using 30 mL of contrast medium. The quality of MP-CTA was assessed quantitatively measuring vessel attenuation, image noise, and contrast-to-noise ratio. MP-CTA was evaluated qualitatively regarding depiction of vessels, cortex differentiation, and motion artifacts (grades 1-4, 1 = best). Mean effective radiation dose was registered. Results were compared to standard renal computed tomography angiography (CTA) (80 mL). Student t test was applied, if variables followed normal distribution. For other variables, nonparametric Mann-Whitney U test was used. RESULTS: All acquisitions were successfully performed, and no patient had to be excluded from the study. MP-CTA enabled high attenuation (aorta: 503 ± 91 HU, renal arteries: 450 ± 73 HU/456 ± 72 HU) at adequate image noise (13.7 ± 1.5) and good contrast-to-noise ratio (34.2 ± 10.2). Good attenuation of renal veins was observed (286 ± 43 HU/282 ± 42 HU). Arterial enhancement was significantly higher compared to renal CTA (aorta: 396 ± 90 HU, renal arteries: 331 ± 74 HU/333 ± 80 HU; P < .001). MP-CTA protocol enabled good image quality of renal arteries (1.5 ± 0.6) and veins (1.7 ± 0.6). Cortex differentiation and motion artifacts were ranked 1.8 ± 0.8 and 1.6 ± 0.8. The mean effective radiation dose was 9 mSv (MP-CTA). CONCLUSIONS: Compared to standard renal CTA, the renal MP-CTA enabled the significant reduction of contrast volume and simultaneously provided a significantly higher arterial attenuation.

Does Virtual Touch IQ elastography help to improve the preoperative diagnosis of parotid tumors: A prospective trial.

BACKGROUND: It is difficult to assess tumors of the parotid gland preoperatively. However, it is essential for the surgeon to know which kind of tumor is present. Ultrasound is the method of choice, but there is still no reliable differential diagnostic tool for determining whether a tumor is malignant or benign. OBJECTIVE: The aim of our study was to examine the value of Virtual Touch imaging quantification (VTIQ) elastograpy in distinguishing between malignant and benign tumors as well as in identifying the most common benign tumor types. METHODS: The parenchyma of 100 parotid glands and 12 lymph nodes of healthy volunteers and 50 tumors of the parotid gland were analyzed via ultrasound, color Doppler ultrasound, and VTIQ, and the results were then compared with histopathology. RESULTS: In comparison with benign tumors, in malignant tumors the tumor border was diffuse, the perfusion higher, and the VTIQ quality much lower. Share wave velocity of the user-defined region of interest was more frequently higher than 6.8 m/s in malignant tumors in comparison to benign tumors. CONCLUSIONS: VTIQ in combination with ultrasound examination provides additional information for distinguishing between benign and malignant tumors and shows promise for integration into preexisting ultrasound protocols.

In vitro study of physical properties of various embolization particles regarding morphology before, during and after catheter passage.

OBJECTIVE: To evaluate various embolization particles on their physical properties with special regard on morphological variability and elasticity. METHODS: 8 embolization particles (EmboCept®, Contour SE® Microspheres, Embosphere® Micorspheres 400 µm, 500 µm, 1300 µm, Embozene® Microspheres, DC Beads®, Embozene Tandem®) were evaluated and graduated from 1-6 microscopically due to morphologic changes in vitro before, during and after their catheter passage by 4 blinded reviewers. To facilitate comparison, microscopic images were provided with a scale. RESULTS: All tested particles showed a homogenous shape and morphology before passage through the simulation catheter. During the passage all particles were elastically deformable, where necessary. After the catheter passage no loss of basic shape was seen. Changes in size were found in 5/8 particles. Grading of morphologic changes varied between mean value of 1.0 and 3.0. No complete destruction or loss of function was seen. CONCLUSION: All tested embolization particles are, regarding their morphological properties in sense of homogenous shape and deformation after catheter passage, a safe treatment option. Tested in vitro no less of functionality regarding physical properties should be expected.

Reduced Periprocedural Analgesia After Replacement of Water for Injection with Glucose 5% Solution as the Infusion Medium for 90Y-Resin Microspheres.

The primary aim of our study was to compare the need for periinterventional on-demand analgesia when water for injection (WFI) was replaced with glucose 5% (G5) for 90Y-resin microsphere administration. METHODS: Forty-one patients who received 77 radioembolization procedures with G5 (2014-2015) were retrospectively matched with 41 patients (77 radioembolization procedures) who received radioembolization with WFI (2011-2014) at our center. The need for on-demand pain medication was chosen as an objective and accessible measure of periprocedural pain experienced by patients. RESULTS: Patients were well matched according to sex, age, tumor type and involvement, and prior antiangiogenic therapies. Periinterventional analgesic requirements were significantly lower for radioembolization procedures performed with G5 than WFI: 5 of 77 (6.5%) versus 29 of 77 (37.7%), P ≤ 0,001, respectively. Early stasis (defined as slowed antegrade flow, before total vascular stasis) occurred in 12 of 154 (7.8%) radioembolization procedures overall and was not different (P ≤ 0.229) between the 2 groups (4/77 [5.2%] vs. 8/77 [10.4%]). CONCLUSION: Slow pulsatile administration of 90Y-resin microspheres with WFI is associated with a low rate of stasis. Replacement of WFI with G5 significantly reduces the need for periprocedural analgesia. These data favor the use G5 for 90Y-resin microsphere implantation in daily practice.

Reducing tumor growth and angiogenesis using a triple therapy measured with Contrast-enhanced ultrasound (CEUS).

BACKGROUND: To evaluate the in vivo response by detecting the anti-angiogenic and invasion-inhibiting effects of a triple-combination-therapy in an experimental-small-animal-squamous-cell-carcinoma-model using the "flash-replenishment" (FR) method to assess tissue hemodynamics via contrast-enhanced-ultrasound (CEUS). METHODS: Human hypopharynx-carcinoma-cells were subcutaneously injected into the left flank of 22-female-athymic-nude-rats. After seven days of subcutaneous tumor growth, FR-measurements were performed on each rat. Treatment-group and control-group were treated every day for a period of one week, with the treatment-group receiving solvents containing a triple therapy of Upamostat®, Celecoxib® and Ilomastat® and the control-group solvents only. On day seven, follow-up measurements were performed using the same measurement protocol to assess the effects of the triple therapy. VueBox® was used to quantify the kinetic parameters and additional immunohistochemistry analyses were performed for comparison with and validation of the CEUS results against established methods (Proliferation/Ki-67, vascularization/CD31, apoptosis/caspase3). RESULTS: Compared to the control-group, the treatment-group that received the triple-therapy resulted in a reduction of tumor growth by 48.6% in size. Likewise, the immunohistochemistry results showed significant decreases in tumor proliferation and vascularization in the treatment-group in comparison to the control-group of 26%(p ≤ 0.05) and 32.2%(p ≤ 0.05) respectively. Correspondingly, between the baseline and follow-up measurements, the therapy-group was associated with a significant(p ≤ 0.01) decrease in the relative-Blood-Volume(rBV) in both the whole tumor(wt) and hypervascular tumor(ht) areas (p ≤ 0.01), while the control-group was associated with a significant (p ≤ 0.01) increase of the rBV in the wt area and a non-significant increase (p ≤ 0.16) in the ht area. The mean-transit-time (mTT) of the wt and the ht areas showed a significant increase (p ≤ 0.01) in the follow-up measurements in the therapy group. CONCLUSION: The triple-therapy is feasible and effective in reducing both tumor growth and vascularization. In particular, compared with the placebo-group, the triple-therapy-group resulted in a reduction in tumor growth of 48.6% in size when assessed by CEUS and a significant reduction in the number of vessels in the tumor of 32% as assessed by immunohistochemistry. As the immunohistochemistry supports the CEUS findings, CEUS using the "flash replenishment"(FR) method appears to provide a useful assessment of the anti-angiogenic and invasion-inhibiting effects of a triple combination therapy.

Visualization, imaging and new preclinical diagnostics in radiation oncology.

Innovative strategies in cancer radiotherapy are stimulated by the growing knowledge on cellular and molecular tumor biology, tumor pathophysiology, and tumor microenvironment. In terms of tumor diagnostics and therapy monitoring, the reliable delineation of tumor boundaries and the assessment of tumor heterogeneity are increasingly complemented by the non-invasive characterization of functional and molecular processes, moving preclinical and clinical imaging from solely assessing tumor morphology towards the visualization of physiological and pathophysiological processes. Functional and molecular imaging techniques allow for the non-invasive characterization of tissues in vivo, using different modalities, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET) and optical imaging (OI). With novel therapeutic concepts combining optimized radiotherapy with molecularly targeted agents focusing on tumor cell proliferation, angiogenesis, and cell death, the non-invasive assessment of tumor microcirculation and tissue water diffusion, together with strategies for imaging the mechanisms of cellular injury and repair is of particular interest. Characterizing the tumor microenvironment prior to and in response to irradiation will help to optimize the outcome of radiotherapy. These novel concepts of personalized multi-modal cancer therapy require careful pre-treatment stratification as well as a timely and efficient therapy monitoring to maximize patient benefit on an individual basis. Functional and molecular imaging techniques are key in this regard to open novel opportunities for exploring and understanding the underlying mechanisms with the perspective to optimize therapeutic concepts and translate them into a personalized form of radiotherapy in the near future.

The carotid plaque imaging in acute stroke (CAPIAS) study: protocol and initial baseline data.

BACKGROUND: In up to 30% of patients with ischemic stroke no definite etiology can be established. A significant proportion of cryptogenic stroke cases may be due to non-stenosing atherosclerotic plaques or low grade carotid artery stenosis not fulfilling common criteria for atherothrombotic stroke. The aim of the CAPIAS study is to determine the frequency, characteristics, clinical and radiological long-term consequences of ipsilateral complicated American Heart Association lesion type VI (AHA-LT VI) carotid artery plaques in patients with cryptogenic stroke. METHODS/DESIGN: 300 patients (age >49 years) with unilateral DWI-positive lesions in the anterior circulation and non- or moderately stenosing (<70% NASCET) internal carotid artery plaques will be enrolled in the prospective multicenter study CAPIAS. Carotid plaque characteristics will be determined by high-resolution black-blood carotid MRI at baseline and 12 month follow up. Primary outcome is the prevalence of complicated AHA-LT VI plaques in cryptogenic stroke patients ipsilateral to the ischemic stroke compared to the contralateral side and to patients with defined stroke etiology. Secondary outcomes include the association of AHA-LT VI plaques with the recurrence rates of ischemic events up to 36 months, rates of new ischemic lesions on cerebral MRI (including clinically silent lesions) after 12 months and the influence of specific AHA-LT VI plaque features on the progression of atherosclerotic disease burden, on specific infarct patterns, biomarkers and aortic arch plaques. DISCUSSION: CAPIAS will provide important insights into the role of non-stenosing carotid artery plaques in cryptogenic stroke. The results might have implications for our understanding of stroke mechanism, offer new diagnostic options and provide the basis for the planning of targeted interventional studies. TRIAL REGISTRATION: NCT01284933.

The role of contrast-enhanced ultrasound in imaging carotid arterial diseases.

The standard of care for the initial diagnosis of carotid artery bifurcation diseases is carotid duplex ultrasound. Carotid abnormalities or difficult examinations may represent a diagnostic challenge in patients with clinical symptoms as well as in the follow-up after carotid endarterectomy, carotid artery stenting or other interventions. A promising new method in the diagnosis and follow-up of pathologic carotid diseases is contrast-enhanced ultrasound (CEUS). In comparison with magnetic resonance imaging or computed tomography, the contrast agents used for CEUS remain within the vascular space and hence can be used to study vascular disease and could provide additional information on carotid arterial diseases. This review describes the current carotid duplex ultrasound examination and compares the pathologic findings with CEUS.

In vivo monitoring of sorafenib therapy effects on experimental prostate carcinomas using dynamic contrast-enhanced MRI and macromolecular contrast media.

PURPOSE: To investigate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with macromolecular contrast media (MMCM) to monitor the effects of the multikinase inhibitor sorafenib on subcutaneous prostate carcinomas in rats with immunohistochemical validation. MATERIALS AND METHODS: Copenhagen rats, implanted with prostate carcinoma allografts, were randomized to the treatment group (n = 8) or the control group (n = 8). DCE-MRI with albumin-(Gd-DTPA)35 was performed at baseline and after 1 week using a clinical 3-Tesla system. The treatment group received sorafenib, 10 mg/kg body weight daily. Kinetic analysis yielded quantitative parameters of tumor endothelial permeability-surface area product (PS; ml/100 ml/min) and fractional blood volume (Vb, %). Tumors were harvested on day 7 for immunohistochemical analysis. RESULTS: In sorafenib-treated tumors, PS (0.62 ± 0.20 vs 0.08 ± 0.09 ml/100 ml/min; P < 0.01) and Vb (5.1 ± 1.0 vs 0.56 ± 0.48%; P < 0.01) decreased significantly from day 0 to day 7. PS showed a highly significant inverse correlation with tumor cell apoptosis (TUNEL; r = -0.85, P < 0.001). Good, significant correlations of PS were also observed with tumor cell proliferation (Ki-67; r = 0.67, P < 0.01) and tumor vascularity (RECA-1; r = 0.72, P < 0.01). MRI-assayed fractional blood volume Vb showed a highly significant correlation with tumor vascularity (RECA-1; r = 0.87, P < 0.001) and tumor cell proliferation (Ki-67; r = 0.82, P < 0.01). CONCLUSION: Results of DCE-MRI with MMCM demonstrated good, significant correlations with the immunohistochemically assessed antiangiogenic, antiproliferative, and proapoptotic effects of a 1-week, daily treatment course of sorafenib on experimental prostate carcinoma allografts.

Time-resolved CT angiography for the detection and classification of endoleaks.

PURPOSE: To assess the feasibility and diagnostic performance of time-resolved computed tomographic (CT) angiography in the detection and classification of endoleaks after endovascular aortic aneurysm repair (EVAR) in high-risk patients. MATERIALS AND METHODS: The study was approved by our ethics committee. Written informed consent was obtained from all participating patients. Fifty-four patients (42 male and 12 female patients; mean age, 70.9 years ± 9.3 [standard deviation]) with either thoracic (n = 8) or abdominal (n = 46) aortic aneurysms treated with a stent-graft were prospectively included. The patients were examined with a time-resolved CT angiographic protocol consisting of 12 low-dose phases (80 kVp; 120 mAs [effective]; scan range, 27 cm), with 60 mL of iomeprol. Patients with abdominal aneurysm repair also underwent contrast material-enhanced (CE) ultrasonography (US). The time delay between contrast enhancement within the stent lumen and the endoleak was measured. Effective radiation dose was calculated from the scanner protocols. Measures of diagnostic performance for the detection of endoleaks were calculated for time-resolved CT angiography, with CE US serving as the reference standard. RESULTS: All time-resolved CT angiographic data sets were diagnostic. Mean effective radiation dose was 14.6 mSv. Four thoracic and 19 abdominal endoleaks were identified by using time-resolved CT angiography. Seventeen of 19 abdominal endoleaks were confirmed with CE US. This rate resulted in a sensitivity of 94%, a specificity of 93%, a positive predictive value of 89%, and a negative predictive value of 96% for time-resolved CT angiography after abdominal EVAR. Type I endoleaks showed significantly earlier mean peak contrast enhancement (0.28 second ± 0.83) compared with that for type II endoleaks (9.17 seconds ± 3.59, P < .0001). CONCLUSION: Time-resolved CT angiography with 12 low-dose phases is feasible for patients after thoracic and abdominal EVAR. The protocol approximates the radiation dose of standard triphasic protocols. Its dynamic information differentiates types of endoleaks and shows high diagnostic performance.

Dynamic contrast-enhanced computed tomography imaging biomarkers correlated with immunohistochemistry for monitoring the effects of sorafenib on experimental prostate carcinomas.

OBJECTIVES: To investigate dynamic contrast-enhanced computed tomography (DCE-CT) for monitoring the effects of sorafenib on experimental prostate carcinomas in rats by quantitative assessments of tumor microcirculation parameters with immunohistochemical validation. MATERIAL AND METHODS: Prostate carcinoma allografts (MLLB-2) implanted subcutaneously in male Copenhagen rats (n=16) were imaged at baseline and after a 1-week treatment course of sorafenib using DCE-CT with iopromide (Ultravist 370, Bayer Pharma, Berlin, Germany) on a dual-source 128-slice CT (Somatom Definition FLASH, Siemens Healthcare, Forchheim, Germany). Scan parameters were as follows: detector width, 38.4 mm; contrast agent volume, 2 mL/kg bodyweight; injection rate, 0.5 mL/s; scan duration, 90 seconds; and temporal resolution, 0.5 seconds. The treatment group (n=8) received daily applications of sorafenib (10 mg/kg bodyweight) via gavage. Quantitative parameters of tumor microcirculation (plasma flow, mL/100 mL/min), endothelial permeability-surface area product (PS, mL/100 mL/min), and tumor vascularity (plasma volume, %) were calculated using a 2-compartment uptake model. DCE-CT parameters were correlated with immunohistochemical assessments of tumor vascularity (RECA-1), cell proliferation (Ki-67), and apoptosis (TUNEL). RESULTS: Sorafenib significantly (P < 0.05) suppressed tumor perfusion (25.1 ± 9.8 to 9.5 ± 6.0 mL/100 mL/min), tumor vascularity (15.6% ± 11.4% to 5.4% ± 2.1%), and PS (8.7 ± 4.5 to 2.7 ± 2.5 mL/100 mL/min) in prostate carcinomas during the treatment course. Immunohistochemistry revealed significantly lower tumor vascularity in the therapy group than in the control group (RECA-1; 181 ± 24 vs. 314 ± 47; P < 0.05). In sorafenib-treated tumors, significantly more apoptotic cells (TUNEL; 7132 ± 3141 vs. 3722 ± 1445; P < 0.05) and significantly less proliferating cells (Ki-67; 9628 ± 1.298 vs. 17,557 ± 1446; P < 0.05) were observed than those in the control group. DCE-CT tumor perfusion correlated significantly (P < 0.05) with tumor cell proliferation (Ki-67; r=0.55). DCE-CT tumor vascularity correlated significantly (P < 0.05) with immunohistochemical tumor cell apoptosis (TUNEL; r=-0.59) and tumor cell proliferation (Ki-67; r=0.68). DCE-CT endothelial PS correlated significantly (P < 0.05) with immunohistochemical tumor cell apoptosis (TUNEL; r=-0.6) and tumor vascularity (RECA-1; r=0.53). While performing corrections for multiple comparisons, we observed a significant correlation only between DCE-CT tumor vascularity (RECA-1) and tumor cell proliferation (Ki-67). CONCLUSION: Sorafenib significantly suppressed tumor perfusion, tumor vascularity, and PS quantified by DCE-CT in experimental prostate carcinomas in rats. These functional CT surrogate markers showed moderate correlations with antiangiogenic, antiproliferative, and proapoptotic effects observed by immunohistochemistry. DCE-CT may be applicable for the quantification of noninvasive imaging biomarkers of therapy response to antiangiogenic therapy.

Comparison of time-resolved CT-angiography, contrast-enhanced ultrasound and digital subtraction angiography in a patient with a small type II endoleak after endovascular aneurysm repair.

We report discordant imaging findings of a small persistent type II endoleak in a 72-year-old man who had undergone endovascular aneurysm repair (EVAR) of an abdominal aortic aneurysm. Although the aneurysm was growing in size digital subtraction angiography could not detect an endoleak, but time-resolved CT-angiography and contrast enhanced ultrasound did detect a small type II endoleak.

Determination of glomerular filtration rate using dynamic CT-angiography: simultaneous acquisition of morphological and functional information.

OBJECTIVES: To determine the feasibility of a dynamic CT angiography-protocol in regard to simultaneous assessment of morphology and function. METHOD AND MATERIALS: Fourteen patients with renal graft dysfunction received a dynamic computed tomography angiography (CTA) using a 128-slice CT-scanner with continuous bi-directional table movement, allowing to cover a scan range of 18 cm within 1.75 seconds. Twelve scans of the entire kidney were acquired every 3.5 seconds with the aim to simultaneously obtain CTA and renal function data. The glomerular filtration rate (GFR) was calculated by a modified Patlak method and compared with creatinine-based formulas (MDRD 4 and endogenous creatinine clearance), that served as reference standard. RESULTS: GFR obtained from dynamic CTA correlates well with the GFR derived by creatinine-based formulas with a correlation coefficient of r = 0.8986; P < 0.0001. The average absolute deviation was 8.1 mL/min. The mean amount of contrast medium required was 35 mL. The average effective dose was 13.8 mSv. CONCLUSION: Dynamic CTA offers the possibility to determine the GFR and thus facilitates simultaneous assessment of morphology and function. Additionally, our dynamic CTA-protocol helps to significantly reduce the amount of contrast medium, which is beneficial for patients with impaired renal function.

Time-resolved computed tomography imaging of the aorta: a feasibility study.

PURPOSE: The aim of this study was to test the feasibility and the additional value of time-resolved computed tomography angiography (CTA) of the aorta, using multiple low-dose phases. MATERIALS AND METHODS: Twenty-two consecutive patients underwent a time-resolved CTA protocol (TR-CTA) of the aorta, either for follow-up of endovascular aneurysm repair (EVAR) or aortic dissection, using a CT scanner with the possibility of bidirectional table movements for dynamic CT imaging (Siemens Definition AS+; 12 phases, temporal resolution 2.5 s/scan, 80 kVp, 120 mAs/rot, scan range 27 cm, 60 mL; Imeron 400, flow 5.0 mL/s). The patients had previously undergone standard CTA (120 kVp, 100 mL contrast agent). Standard CTA after EVAR and aortic dissection were triphasic and biphasic protocols, respectively. Effective radiation dose and maximum Hounsfield unit values were compared between the TR-CTA and standard CTA. Image quality was rated for TR-CTA. RESULTS: Fifteen patients underwent TR-CTA for follow-up after EVAR; 4 were examined for follow-up after dissection and 3 for both, that is, aortic dissection treated with an endovascular stent. Mean effective dose of TR-CTA for the scan range of 27 cm (15.3+/-1.1 mSv) was comparable with the biphasic standard CTA protocols (16.2+/-2.4 mSv; P=0.29). Triphasic protocols resulted in 23.7+/-4.9 mSv (P<0.0001). Hounsfield unit values were not significantly different. Most of the examinations (91%) were fully evaluable, whereas 9% were of limited evaluability because of high image noise. None of the examinations was nondiagnostic. DISCUSSION: TR-CTA consisting of multiple low-dose phases leads to a clear depiction of the angiographic information and is feasible for follow-up after EVAR and aortic dissection. Considering the limited scan range, radiation dose is comparable with the standard biphasic CTA protocol, but dynamic information may provide additional information.

Single-phase dual-energy CT allows for characterization of renal masses as benign or malignant.

PURPOSE: To evaluate the diagnostic accuracy of dual-energy CT (DECT) in renal mass characterization using a single-phase acquisition. MATERIALS AND METHODS: A total of 202 patients (148 males, 54 females; 63 +/- 13 years) with ultrasound-based suspicion of a renal mass underwent unenhanced single energy and nephrographic phase DECT on a dual source scanner (Siemens Somatom Definition Dual Source, n = 174; Somatom Definition Flash, n = 28). Scan parameters for DECT were: tube potential, 80/100 and 100/Sn140 kVp; exposure, 404/300 and 96/232 effective mAs; collimation, 14 x 1.2/32 x 0.6 mm. Two abdominal radiologists assessed DECT and SECT image quality and noise on a 5-point visual analogue scale. Using solely the DE acquisition including virtual nonenhanced (VNE) and color coded iodine images that enable direct visualization of iodine, masses were characterized as benign or malignant. In a second reading session after 34 to 72 (average: 55) days, the same assessment was again performed using both the true nonenhanced (TNE) and nephrographic phase scans thereby simulating conventional single-energy CT. Sensitivities, specificities, diagnostic accuracies, and interpretation times and were recorded for both reading paradigms. Dose reduction of a single-phase over a dual-phase protocol was calculated. Results were tested for statistical significance using the paired Wilcoxon signed rank test and student t test. Differences in sensitivities were tested for significance using the McNemar test. RESULTS: Of the 202 patients, 115 (56.9%) underwent surgical resection of renal masses. Histopathology showed malignancy in 99 and benign tumors in 18 patients, in 48 patients (23.7%), follow-up imaging showed size stability of lesions diagnosed as benign, and 37 patients (18.3%) had no mass. Based on DECT only, 95/99 (96.0%) patients with malignancy and 96/103 (93.2%) patients without malignancy were correctly identified, for an overall accuracy of 94.6%. The dual-phase approach identified 96/99 (97.0%) and 98/103 (95.1%), accuracy 96.0%, P > 0.05 for both. Mean interpretation time was 2.2 +/- 0.8 minutes for DECT, and 3.5 +/- 1.0 minutes for the dual-phase protocol, P < 0.001. Mean VNE/TNE image quality was 1.68 +/- 0.65/1.30 +/- 0.59, noise was 2.03 +/- 0.57/1.18 +/- 0.29, P < 0.001 for both. Omission of the true unenhanced phase lead to a 48.9 +/- 7.0% dose reduction. CONCLUSION: DECT allows for fast and accurate characterization of renal masses in a single-phase acquisition. Interpretation of color coded images significantly reduces interpretation time. Omission of a nonenhanced acquisition can reduce radiation exposure by almost 50%.