Contrast-enhanced Studies Research Articles

4D-Dynamic Contrast-Enhanced MRI for Preoperative Localization in Patients with Primary Hyperparathyroidism.

Our aim was to test the hypothesis that our recently introduced 4D-dynamic contrast-enhanced MR imaging with high spatial and temporal resolution has equivalent accuracy to 4D-CT for preoperative gland localization in primary hyperparathyroidism without requiring exposure to ionizing radiation. Inclusion criteria were the following: 1) confirmed biochemical diagnosis of primary hyperparathyroidism, 2) preoperative 4D-dynamic contrast-enhanced MR imaging, and 3) surgical cure with >50% decrease in serum parathyroid hormone intraoperatively. 4D-dynamic contrast-enhanced studies were reviewed independently by 2 neuroradiologists to identify the side, quadrant, and number of abnormal glands, and compared with surgical and pathologic results. Fifty-four patients met the inclusion criteria: 37 had single-gland disease, and 17, multigland disease (9 with double-gland hyperplasia; 3 with 3-gland hyperplasia; and 5 with 4-gland hyperplasia). Interobserver agreement (κ) for the side (right versus left) was 0.92 for single-gland disease and 0.70 for multigland disease. Interobserver agreement for the quadrant (superior versus inferior) was 0.70 for single-gland disease and 0.69 for multigland disease. For single-gland disease, the gland was correctly located in 34/37 (92%) patients, with correct identification of the side in 37/37 (100%) and the quadrant in 34/37 (92%) patients. For multigland disease, the glands were correctly located in 35/47 (74%) patients, with correct identification of the side in 35/47 (74%) and the quadrant in 36/47 (77%). The proposed high spatial and temporal resolution 4D-dynamic contrast-enhanced MR imaging provides excellent diagnostic performance for preoperative localization in primary hyperparathyroidism, with correct gland localization of 92% for single-gland disease and 74% in multigland disease, superior to 4D-CT studies.

Abstract No. 489 Ultralow contrast dose using catheter-directed computed tomography angiography in patients with renal insufficiency

CT angiography offers excellent anatomic detail necessary for vascular procedural planning including endovascular aneurysm repair (EVAR). However, patients with renal insufficiency are at risk for acute renal failure due to iodinated contrast administration. Catheter-directed CT angiography is a technique in which dilute iodinated contrast is injected into an intra-aortic pigtail catheter during the CT scan. The purpose of this study was to evaluate the safety and efficacy of this technique. Retrospective review of patients with renal insufficiency (GFR<30) who underwent catheter-directed CT angiography for one of the following indications: preoperative EVAR planning, evaluation of arterial occlusive disease or endoleak evaluation following EVAR. A pigtail catheter was advanced into the aorta using standard angiographic technique. In the CT scanner, the pigtail catheter was injected with one third diluted contrast (20 mL iodinated contrast with 40 mL saline) at a rate of 6 mL/s for a total of 60 mL. A 6 second CT scanner delay was utilized. Technical success, complications, pre and post creatinine and GFR, Hounsfield units (HU) attained in the aorta were recorded. Values > 150 HU were considered sufficient. Subjective image assessment was performed by 2 observers to assess clinical adequacy for procedural planning. From 2015-2019, 11 patients, mean age 74, 9M:2F, underwent catheter-directed CT angiography. The mean contrast usage was 23 mL. There were no complications and a 100% technical success. The preoperative baseline Cr and GFR was 2.9 ± 0.7 and 22 ± 6. The post procedure Cr and GFR were 2.9 ± 0.7 and 22 ± 7. There were no cases of acute renal failure. The mean HU in the aorta was 397 ± 294. Subjective assessment showed all studies to be clinically adequate for their respective indications. Catheter-directed CT angiography is a safe and effective technique for obtaining contrast-enhanced vascular studies in patients with renal insufficiency using an ultralow contrast dose.

Noncontrast Magnetic Resonance Angiography Clinical Application in Pre-Liver Transplant Recipients With Impaired Renal Function.

Image evaluation of the vascular architecture is essential before living donor liver transplantation (LDLT). However, the use of contrast-enhanced study in recipients with impaired renal function is limited due to the risk of acute kidney injury and nephrogenic systemic fibrosis. Therefore, a contrast medium-free method is both valuable and necessary for preoperative vascular evaluation. Recent literature reported inflow-sensitive inversion recovery (IFIR) magnetic resonance angiography (MRA) without the use of a contrast medium to be a reproducible and noninvasive tool to assess hepatic vasculature with adequate-to-good image quality. The purpose of this study is to clinically apply IFIR MRA preoperatively in LDLT recipients. We retrospectively reviewed 31 LDLT recipients with renal function impairment from March 2013 to August 2018 who received IFIR MRA as a pretransplant vascular architecture evaluation and who underwent a subsequent LDLT. The image findings were assessed for subjective image quality and were compared with intraoperative findings. Our results showed that the pretransplant vascular anatomy was well correlated with intraoperative findings in all recipients. Successful ratings with image quality scores ≥2 for proper hepatic arteries (PHAs), portal veins, and inferior vena cavas (IVCs) were 100.0%, 96.8%, and 93.5%, respectively. Readable ratings with imaging quality score ≥1 for left and right hepatic arteries and gastroepiploic arteries were 83.9%, 96.7%, and 22.6%, respectively. We also found that recipients with higher Model for End-Stage Liver Disease scores (>23) had lower image quality scores for PHAs (P=0.003) and IVCs (P= 0.046). However, images were still satisfactory for pre-liver transplantation (LT) vascular evaluation. In conclusion, in pre-LT recipients with impaired renal function, IFIR MRA is a feasible and reproducible image modality.

Unilateral Nonvisualization of a Transverse Dural Sinus on Phase-Contrast MRV: Frequency and Differentiation from Sinus Thrombosis on Noncontrast MRI.

Unilateral decreased/nonvisualization of a transverse dural sinus on MRV poses a diagnostic dilemma when gadolinium administration is contraindicated. We determined the frequency of unilateral decreased/nonvisualization of the transverse dural sinus and the performance of pregadolinium MR imaging sequences in diagnosing transverse sinus thrombosis in the presence of unilateral decreased/nonvisualization on phase-contrast MRV. We conducted a retrospective review of consecutive 3D phase-contrast MRV (VENC, 30 cm/s) and routine brain imaging (noncontrast sagittal T1, axial T2, FLAIR, DWI, GRE, and postgadolinium 3D-MPRAGE images) performed during a 3-year period for a total of 208 patients. Nonvisualization of a transverse dural sinus was defined as ≥50% nonvisualization of the transverse sinus caliber versus the contralateral side on MRV. Noncontrast imaging findings were considered abnormal when hyperintense signal was present on T2, FLAIR, T1, and DWI, and there were T2* blooming artifacts on GRE and DWI. Postgadolinium 3D-MPRAGE was used to confirm the diagnosis of transverse sinus thrombosis. Nonvisualization of a transverse dural sinus was observed in 72/208 (34.6%) patients on MRV; 56/72 (77.8%) were without transverse sinus thrombosis, and 16/72 (22.2%) patients had transverse dural sinus thrombosis. Nonvisualization of a transverse dural sinus was seen in 56/192 (29.2%) patients without transverse sinus thrombosis and 16/16 (100%) with transverse sinus thrombosis. Abnormal findings on DWI (transverse sinus hyperintense signal or T2* blooming artifact) are 93.8% sensitive and 100.0% specific for transverse sinus thrombosis. Other noncontrast MR imaging sequences ranged from 56.3%-68.8% sensitive and 91.1%-100.0% specific. Nonvisualization of a transverse dural sinus is a frequent phenomenon on phase-contrast MRV. DWI can be effectively used to exclude sinus thrombosis when nonvisualization of a transverse dural sinus is a diagnostic conundrum on phase-contrast MRV and contrast-enhanced studies are contraindicated.

Prevalence of Chronic Kidney Disease (CKD) in Lymphoma Survivors

Background: Improved management of lymphoma patients has resulted in increasing numbers of long term survivors suffering from a broad spectrum of late effects of treatment. In particular lymphoma patients are exposed to nephrotoxic insults from therapy and its complications such as sepsis and tumor lysis syndrome, as well as from repeated contrast-enhanced imaging studies. Multiple episodes of acute kidney injury (AKI) can lead to chronic kidney disease (CKD) in survivors. In a recent retrospective cohort study 34% of lymphoma patients were found to have CKD at 3 year follow up (1). Here we describe the progressive development of CKD in a cohort of lymphoma survivors over a 10-year period. Methods: Three hundred and ninety-seven consecutive adults with biopsy proven lymphoma diagnosed and treated at our center between 2003 and 2017 were included in this study. Baseline characteristics including lymphoma subtype, age, race, gender, lymphoma therapy, number of CT scans and episodes of AKI were recorded. CKD, hypertension, diabetes mellitus (DM), body mass index (BMI), uric acid levels and infection with human immunodeficiency virus or hepatitis were also recoded at baseline. Obesity was defined as BMI ≥ 30. Glomerular filtration rate (GFR) was calculated using the CKD-EPI equation at diagnosis (time 0 or baseline) and after 1, 2, 5 and 10 years to calculate rate of GFR decline over time. CKD was defined as GFR &lt;60 ml/min. Statistical analysis was performed in SAS 9.4. Probability of developing CKD over 10 years was derived from Kaplan-Meier analysis. Multivariate regression analysis was used to identify factors predicting development of CKD. Results: Of 397 patients studied 174 (44%) had high grade and 159 (40%) low grade non-Hodgkin lymphoma (NHL), 61 (15%) had Hodgkin lymphoma and 3 (1%) grey zone lymphoma. Median age was 55 y (18-88), 54% were male, 60% were African Americans. At presentation 42% had hypertension, 15% had DM, 11% had HIV, 13% had hyperuricemia, 32% were obese and 13% had CKD.A total of 61% received chemoimmunotherapy, 24% received chemotherapy, 9% received immunotherapy and 6% were observed without treatment. GFR declined progressively from 96.5 mL/min per 1.73 m2 at baseline, to 77.4 mL/min per 1.73 m2 at 10 years with a rate of decline of 4.6 mL/min per 1.73 m2 per year. CKD developed in 125 patients (31%) over the study period. In multivariate analysis age (HR:1.07, CI95:1.04-1.08, p&lt;0.001), hypertension (HR 2.01, CI95:1.2-3.4, p&lt;0.001), hyperuricemia (HR 1.2, CI95:1.03-1.3, p&lt;0.001), DM (HR 2.5 CI95:1.2-5.3, p&lt;0.05) were associated with higher likelihood and BMI (HR 0.96, CI95: 0.9-0.99, p&lt;0.001) with lower likelihood of CKD development. Conclusion: In this study CKD was a significant long-term complication in lymphoma survivors. With a progressive fall in their GFR, increasing numbers of lymphoma survivors developed CKD over the study period reaching 31% at 10 years. Age, hypertension, DM and raised uric acid at diagnosis increased the risk of CKD while obesity appeared protective. Renal injury in lymphoma survivors is probably multi-factorial. Further studies are needed to develop treatment approaches with reduced risk of CKD. 1. Ubukata M, Hara M, Nishizawa Y, Fujii T, Nitta K, Ohta A. Prevalence and mortality of chronic kidney disease in lymphoma patients: A large retrospective cohort study. Medicine. 2018;97(2):e9615. Disclosures No relevant conflicts of interest to declare.

Impact of Single Dose Photons and Carbon Ions on Perfusion and Vascular Permeability: A Dynamic Contrast-Enhanced MRI Pilot Study in the Anaplastic Rat Prostate Tumor R3327-AT1.

We collected initial quantitative information on the effects of high-dose carbon (12C) ions compared to photons on vascular damage in anaplastic rat prostate tumors, with the goal of elucidating differences in response to high-LET radiation, using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Syngeneic R3327-AT1 rat prostate tumors received a single dose of either 16 or 37 Gy 12C ions or 37 or 85 Gy 6 MV photons (iso-absorbed and iso-effective doses, respectively). The animals underwent DCE-MRI prior to, and on days 3, 7, 14 and 21 postirradiation. The extended Tofts model was used for pharmacokinetic analysis. At day 21, tumors were dissected and histologically examined. The results of this work showed the following: 1. 12C ions led to stronger vascular changes compared to photons, independent of dose; 2. Tumor growth was comparable for all radiation doses and modalities until day 21; 3. Nonirradiated, rapidly growing control tumors showed a decrease in all pharmacokinetic parameters (area under the curve, Ktrans, ve, vp) over time; 4. 12C-ion-irradiated tumors showed an earlier increase in area under the curve and Ktrans than photon-irradiated tumors; 5. 12C-ion irradiation resulted in more homogeneous parameter maps and histology compared to photons; and 6. 12C-ion irradiation led to an increased microvascular density and decreased proliferation activity in a largely dose-independent manner compared to photons. Postirradiation changes related to 12C ions and photons were detected using DCE-MRI, and correlated with histological parameters in an anaplastic experimental prostate tumor. In summary, this pilot study demonstrated that exposure to 12C ions increased the perfusion and/or permeability faster and led to larger changes in DCE-MRI parameters resulting in increased vessel density and presumably less hypoxia at the end of the observation period when compared to photons. Within this study no differences were found between curative and sub-curative doses in either modality.

The Potentials and Role of Diffusion-Weighted Magnetic Resonance Imaging in Evaluating the Efficiency of Antitumor Treatment of Patients with Breast Liver Metastasis

Objective. To compare the informative value of using dynamic magnetic resonance imaging (MRI) and diffusion-weighted MRI (DW-MRI) in patients with breast liver metastasis during chemotherapy.Material and methods. The investigation enrolled 30 patients with breast liver metastasis during their treatment. The results of standard intravenous contrast-enhanced abdominal MRI studies (by evaluating the liver in the arterial, venous, and delayed phases) were compared with those of DW-MRI with different B-factor values (50, 400 and 800 sec/mm2).Results. Comparison of the findings of initial studies prior to chemotherapy (those of only dynamic intravenous contrast-enhanced MRI and only DW-MRI) revealed a complete correspondence with the number of detected foci in 10 patients. Ten patients had a larger number of metastatic foci at DW-MRI than at intravenous contrast-enhanced MRI, in the aggregate by 44 foci more (of them 36 foci measured less than 1 cm). The remaining 10 of the 30 patients were found to have multiple, unquantifiable (more than 20–40) metastatic foci of various sizes (1–6 cm) at both intravenous contrast-enhanced MRI and DW-MRI. Nineteen of the 30 patients were followed up during their chemotherapy. Seven of the 19 patients showed a stabilized liver metastatic process that was similarly evidenced by both techniques. Eleven of the 19 patients were observed to have a progressive metastatic process that was reflected by the similar increase in the number and size of metastases in 5 of the 11 patients, as shown by both of the above techniques. In the remaining 6 of the 11 patients, the number of newly detected liver tumors proved to be larger at DW-MRI than at intravenous contrast-enhanced MRI. Both techniques showed that the last patient of the 19 cases had a decrease in the number of small liver metastases that maintained their sizes (less than 1 cm).Conclusion. DW-MRI has been shown to be much more effective in detecting metastases than conventional intravenous contrast-enhanced MRI, which necessitates the inclusion of this technique in standard abdominal MRI protocols for patients with liver metastasis.

Endoscopic Ultrasound Features Associated with Malignancy andAggressiveness of Nonhypovascular Solid Pancreatic Lesions: Resultsfrom a Prospective Observational Study.

On contrast-enhanced imaging studies, nonhypovascular (i. e., isovascular and hypervascular) patterns can be observed in solid pancreatic lesions (SPLs) of different nature, prognosis, and management. We aimed to identify endoscopic ultrasound (EUS) features of nonhypovascular SPLs associated with malignancy/aggressiveness. The secondary aims were EUS tissue acquisition (EUS-TA) outcome and safety in this setting of patients. This prospective observational study included patients with nonhypovascular SPLs detected on cross-sectional imaging and referred for EUS-TA. Lesion features (size, site, margins, echotexture, vascular pattern, and upstream dilation of the main pancreatic duct) were recorded. Malignancy/aggressiveness was determined by evidence of carcinoma at biopsy/surgical pathology, signs of aggressiveness (perineural invasion, lymphovascular invasion, and/or microscopic tumor extension/infiltration or evidence of metastatic lymph nodes) in the surgical specimen, radiologic detection of lymph nodes or distant metastases, and/or tumor growth > 5 mm/6 months. Uni- and multivariate analyses were performed to assess the primary aim. A total of 154 patients with 161 SPLs were enrolled. 40 (24.8 %) lesions were defined as malignant/aggressive. Irregular margins and size > 20 mm were independent factors associated with malignancy/aggressiveness (p < 0.001, OR = 5.2 and p = 0.003, OR = 2.1, respectively). However, size > 20 mm was not significant in the subgroup of other-than-neuroendocrine tumor (NET) lesions. The EUS-TA accuracy was 92 %, and the rate of adverse events was 4 %. Irregular margins on EUS are associated with malignancy/aggressiveness of nonhypovascular SPLs. Size > 20 mm should be considered a malignancy-related feature only in NET patients. EUS-TA is safe and highly accurate for differential diagnosis in this group of patients.

3256Long-term safety of stereotactic body radiotherapy for ablation of ventricular tachycardia: a multicentric study

Abstract Background Contemporary stereotactic body radiotherapy (SBRT) enables to accurately concentrate high radiation doses to small volumes of myocardial tissue. There is a rising interest in using SBRT to modify arrhythmogenic substrate in patients with previously failed radiofrequency catheter ablation. However, data on the safety of SBRT for the treatment of VT are lacking. Purpose This study evaluated the long-term safety of SBRT for the treatment of VT. Methods SBRT was performed in patients with structural heart disease and failed catheter ablation for VT. The critical part of the VT substrate was identified by electroanatomic mapping (EAM) using a combination of voltage mapping, pace mapping, and activation mapping; and it was marked on a contrast-enhanced computer tomography study as a target for radioablation. SBRT was performed using a radiosurgery system with real-time motion tracking using the tip of the electrode of an indwelling defibrillator as a fiducial marker. A total radiation dose of 25 Gy was delivered to the ablation target in a single session during free breathing. Radiation-induced toxicity was evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Results Between 2014 and 2018, 18 patients from two electrophysiology centres underwent SBRT for recurrent, drug-resistant VT after previously failed catheter ablation (17 male, 1 female; mean age 63±9 years; 14 ischemic cardiopathy, 3 dilated cardiopathy, 1 fibroma). The mean volume of the ablation target was 34±17 ml, and the mean duration of the therapy was 78±14 minutes. No patient exhibited acute (up to 3 months) elevation of troponin, pericardial effusion, or a decrease in left ventricular ejection fraction from baseline. Four patients developed acute mild nausea, which waned after antiemetic drugs. Two patients gradually developed significant progression of mitral regurgitation after SBRT. One of the patients was treated medically (grade 3 toxicity), but the other had to undergo mitral valve replacement (grade 4 toxicity). No other cardiac or pulmonary radiation related toxicity was observed during a median follow-up of 23 months. Three patients died at 54, 43, and 18 month after SBRT. None of the deaths was related to VT recurrence or complication of SBRT. CARTO, Radiation dose and Survival Conclusions This is the largest series of patients who underwent EAM-guided SBRT for VT as a bailout therapy after previously failed radiofrequency catheter ablation. Our preliminary data indicate the feasibility and safety of the procedure. To further investigate long-term safety and efficacy of SBRT for VT, we initiated a prospective multicentric study (NCT03819504). Acknowledgement/Funding Supported by RVO-FNOs/2014

EARLY VENTRICULAR AND TISSUE REMODELING IN THE FIRST WEEK AFTER ACUTE MYOCARDIAL INFARCTION: A PILOT STUDY

Tissue injury in acute myocardial infarction has several components, including myocardial edema and cardiomyocyte necrosis. Severe infarction can be complicated by microvascular obstruction (MVO) and hemorrhage (H). MVO has been shown to occur and expand early after reperfusion therapy in animal models. In humans, the presence of MVO is independently associated with adverse ventricular remodelling and outcome. As opposed to animal studies, the time course of evolution of microvascular injury is not well understood in humans, especially in the very acute phase after reperfusion injury. The aim of this pilot study was to investigate the temporal evolution of tissue injury (MVO, infarct size) and ventricular function within the first week after reperfused acute ST-elevation myocardial infarction. The study was approved by the institutional ethics committee and all patients gave written informed consent. A comprehensive cardiac MRI study was performed on day 0 or 1 after reperfused STEMI, and compared to a follow-up CMR study on day 5-7. All 21 patients had received primary PCI and guideline-based medical therapy. The contrast-enhanced CMR study assessed LV volumetric parameters, LVEF, and quantified edema, necrosis, MVO and hemorrhage. Twenty-one patients were included, of whom twelve had no microvascular injury (I), seven had microvascular obstruction (MVO), and two had hemorrhagic infarcts (H). Thirteen completed the follow-up. At baseline, hemorrhagic MI had larger infarct size, greater MVO, larger edema, larger ventricular end-diastolic volume and lower LVEF than infracts without microvascular injury. Patients with MVO had larger infarcts than patients without microvascular injury, however, this did not lead to a difference in LVEDV or LVEF (table 1). At follow-up, patients with MVO maintained the extent of MVO, e.g. it did neither increase nor decrease in size. Likewise, infarct size, amount of edema, LVEDV and LVEF did not change between day 0/1 and day 5-7, independent of the presence or absence of MVO (table 2). As opposed to animal models, in our patient study we did not observe any expansion of MVO in the first week after reperfused STEMI. Also, there was no change in the extent of edema, infarct size from day 0/1 to day 5-7, in patients with or without MVO. Patients with MVO had larger infarct size from the beginning; the largest infarct size and worst LV function was observed in patients with hemorrhagic myocardial infarction. Patient numbers were limited in this pilot study.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Possibilities of Computed Tomography Urography and Magnetic Resonance Urography as Up-To-Date and Informative Techniques in the Diagnosis of Traumatic Ureteral Strictures

Objective. To assess the sensitivity of computed tomography urography (CTU) and magnetic resonance urography (MRU) (native versus contrast-enhanced studies) in patients with traumatic ureteral strictures.Material and methods. The data of 51 CTUs and 34 MRUs made in patients with upper urinary tract injuries were prospectively analyzed. The studies were performed using an Aquilion Prime 160-slice scanner (Toshiba, Japan) and high-field devices at a magnetic field strength of 1.5 Tesla Vantage Atlas (Toshiba, Japan) and at 3.0 Tesla Ingenia (Philips, Netherlands). Excretory urography was also carried out in 92.2% of cases; ultrasound examination was made in 74.5%. The degree of obstruction, its causes, the state of the adjacent structures, and the presence of complications were assessed.Results. All (100%) CTU studies correctly estimated the level of stricture of the ureter; the lower third of the organ was involved most frequently (68.6%). MRU identified traumatic strictures in 94.0% of cases. MRU and CTU could be confined to native series in 51.0 and 27.5% of patients, respectively. MRU more commonly revealed the changes concurrent with injuries: there was diffuse ureter wall thickening in 44.1% (27.5% at for CTU), periureteral fat infiltration in 43.1% (37.2% at CTU), and pelvic fluid accumulation in 9.8% (7.8% at with CTU). The techniques could also establish the presence of sinus tracts: MRU was useful in the preoperative imaging of pathological fistulas in 100%. CTU was able to demonstrate the leakage of a contrast agent and/or its flow into the vagina in 66.7%.Conclusion. MRU demonstrates the sensitivity comparable to that of CTU in detecting ureteral injuries (including in diagnosing complications, such as fistulas) and can be used in patients with contraindications to CTU and, due to the absence of ionizing radiation, for follow-up studies.

Synthesis, quantum chemistry analysis and pre-clinical in vivo evalution of magnetic resonance imaging abilities of paramagnetic manganese complex with 2,3-dimercaptosuccinate (succimang)

Aim of the study. We have carried out the synthesis of complex of Manganese(II) with dimercaptosuccinic acid (DMSA), applied the quantum chemistry analysis for evaluation of most stable form of the Mn- DMSA complex and studied it’s uptake and imaging properties in normal and tumoral tissues in veterinary patients (cats with tumors)Material and methods. The synthesis of the 2.3-dimercaptosuccinic acid (COOH-CHSH-CHSH-COOH) has been carried out using modified technique proposed by A.I. Busev [Busev A.I. 1972]. Using phantoms filled in with 0.05 mM – 16 mM solutions of the agent we quantified the R1 relaxivity. Imaging properties of the 0.5 M solution of the Mn-(DMSA)2 were evaluated when performing the contrastenhanced studies in veterinary patients (cats with adenofibrous tumors and angiofibromas, nine animals) using T1-w spin-echo mode.Results. As result of quantum chemistry analysis it was shown that the most stable complex of Mn(II) with DMSA is the molecule Mn-(DMSA)2. The R1 relaxivity of the Mn-(DMSA)2 complex in the water solution was as high as 3.2 1/(mM*s). In normal control animals the Mn-(DMSA)2 provided highly intensive enhancement of renal parenchyma and mild enhancement of liver, spleen and bone marrow. In animals with tumors the Mn-(DMSA)2 enhanced the T1-w spin-echo images of angiofibromas and fibroadenomas in both peripheral (index of enhancement = 1.87 ± 0.09, p &lt; 0.01) and central (index of enhancement = 1.59 ± 0.07, p &lt; 0.01) parts of the tumor.Conclusion. The imaging properties of the Mn-(DMSA)2 make an argue for real possibility of production of new non-Gadolinium paramagnetic contrast agents specific to tumors. Further study of the Mn-(DMSA)2 complex as paramagnetic contrast agent is of interest and useul.

CT imaging features of canine thymomas.

Canine thymomas have been evaluated based on clinical features, treatment options, surgical excision, and outcomes with limited information on specific CT features. The objective of this retrospective, descriptive, cross-sectional study was to describe the CT characteristics of confirmed thymomas and to compare these imaging features to outcome. A total of 22 dogs met the inclusion criteria of histologically confirmed thymomas with concurrent CT imaging. Tumor size varied widely ranging from small and well-circumscribed to large and invasive. Delayed-phase, contrast-enhanced CT studies were best for determining the degree of contrast enhancement in tumors. Of these, 19 of 22 masses had heterogeneous enhancement and three of 22 masses had homogeneous enhancement. Vascular invasion was present in seven of 22 cases. Larger tumors were associated with vascular invasion (height: P=.04; width and volume: P=.02). On precontrast CT, larger tumors (16/21) were heterogeneous and cystic, with smaller tumors (5/21) being more homogeneous (all values P<.05). A larger size was associated with recurrence in fully resected masses (height: P=.03), but not a shorter outcome (P>.3 for all size dimensions). Postoperative complications and incomplete tumor resection were associated with shorter outcome (both values P<.01). Metastasis was confirmed in four cases. There were six cases with lymphadenopathy noted on CT; five of the six cases did not have evidence of metastasis. Larger tumors were more likely to be cystic and associated with vascular invasion.

Validation of Region of Interest Measurements for the Objective Assessment of Post-Contrast Enhancement of Renal Lesions on MRI.

The aim of this study was to validate the use of region of interest (ROI) measurements in MRI to objectively assess for enhancement in suspected solid renal masses and to determine a minimum threshold value for true enhancement. Contrast-enhanced renal MRI studies performed between January 2015 and December 2017 for patients with a known renal mass who had subsequent biopsy, or partial/radical nephrectomy were included. Two body imaging fellows independently measured the mean ROI values of renal masses, normal renal parenchyma, the ipsilateral psoas muscle and external air on the pre- and post-contrast sequences. The absolute and percentage changes in the mean ROI values were calculated. The readers were blinded to the pathology results. 104 patients were included in this study (mean age of 65 years; 58 males and 46 females). 74 patients (71%) had a diagnosis of renal cell carcinoma (RCC). Pathology showed clear-cell RCC in 55%, papillary RCC in 22%, and other RCC subtypes in 23%. There were 30 non-RCC renal lesions (29%), including oncocytoma, renal papillary adenoma, and renal metastasis.The minimum percentage change in ROI values in the pre- versus post-contrast images for all pathology-proven RCCs was 23% (range: 23-437%, mean: 143%); this represents relative enhancement and was referred to as the Signal Intensity Index (SII). The percentage change for normal renal parenchyma ranged from 32-317%. The maximum percentage change in ROI values for pathology proven renal cysts was 13% (range: -5-13%, mean: 3.5%). There was excellent inter observer agreement between the two readers [Intra-class correlation coefficient (r) 0.81]. The percentage change in ROI values (SII) can be a helpful tool in the objective assessment of true enhancement of renal masses and can supplement subtraction images. The minimum threshold for enhancement in our study was 23%. Enhancement of a renal lesion can be determined using the objective tool of ROI measurements in the pre- and post-contrast MR images with a percentage change of 20% or above indicating enhancement. This is an additional objective tool, which in conjunction with the subtraction images may improve detection and appropriate diagnosis of renal lesions. It could also be helpful in cases where the subtraction images are degraded by motion artefact.

Comparative study of multi-slice spiral CT urography and contrast-enhanced ultrasound in the diagnosis of renal tuberculosis

Objective To compare the effect of multi-slice spiral CT urography and contrast-enhanced ultrasound in the diagnosis of renal tuberculosis. Methods From January 2015 to December 2017, 174 cases of suspected renal tuberculosis were analyzed retrospectively, including 105 cases of renal tuberculosis and 69 other cases. Multi-slice spiral CT urography and contrast-enhanced ultrasound had been performed to compare diagnostic utility and two imaging techniques. Results The sensitivity, negative predictive value and coincidence rate of multi-slice spiral CT urography were higher than those of contrast ultrasound(P 0.05). The rate of renal parenchyma cicatrization and calcification in renal area was higher than that of contrast-enhanced ultrasound in the diagnosis of renal tuberculosis with multi-slice spiral CT urographic imaging(P 0.05). Conclusions The utility of multi-slice spiral CT urography in the diagnosis of renal tuberculosis is superior to that of ultrasound, especially in renal parenchyma scar and renal calcification, but the operation is simple, safe and cheap. Key words: Tuberculosis, Renal; Tomography, Spiral Computed; Computed Tomography Angiography

The Predictive Value of Hyperuricemia on Renal Outcome after Contrast-Enhanced Computerized Tomography.

The aim of this study was to determine whether elevated serum level of uric acid (sUA) could predict renal outcome after contrast-enhanced computerized tomography (CCT). We used a historical cohort of 58,106 non-dialysis adult patients who received non-ionic iso-osmolar CCT from 1 June 2008 to 31 March 2015 to evaluate the association of sUA and renal outcome. The exclusion criteria were patients with pre-existing acute kidney injury (AKI), multiple exposure, non-standard volume of contrast, and missing data for analysis. A total of 1440 patients were enrolled. Post-contrast-AKI (PC-AKI), defined by the increase in serum creatinine ≥ 0.3 mg/dL within 48 h or ≥50% within seven days after CCT, occurred in 180 (12.5%) patients and the need of hemodialysis within 30 days developed in 90 (6.3%) patients, both incidences were increased in patients with higher sUA. sUA ≥ 8.0 mg/dL was associated with an increased risk of PC-AKI (odds ratio (OR) of 2.62; 95% confidence interval (CI), 1.27~5.38, p = 0.009) and the need of hemodialysis (OR, 5.40; 95% CI, 1.39~21.04, p = 0.015). Comparing with sUA < 8.0 mg/dL, patients with sUA ≥ 8.0 mg/dL had higher incidence of PC-AKI (16.7% vs. 11.1%, p = 0.012) and higher incidence of hemodialysis (12.1% vs. 4.3%, p < 0.001). We concluded that sUA ≥ 8.0 mg/dL is associated with worse renal outcome after CCT. We suggest that hyperuricemia may have potential as an independent risk factor for PC-AKI in patients receiving contrast-enhanced image study.

Symptomatic Carotid Plaques Demonstrate Less Leaky Plaque Microvasculature Compared With the Contralateral Side: A Dynamic Contrast-Enhanced Magnetic Resonance Imaging Study.

BackgroundRupture of a vulnerable carotid atherosclerotic plaque is an important underlying cause of ischemic stroke. Increased leaky plaque microvasculature may contribute to plaque vulnerability. These immature microvessels may facilitate entrance of inflammatory cells into the plaque. The objective of the present study is to investigate whether there is a difference in plaque microvasculature (the volume transfer coefficient K trans) between the ipsilateral symptomatic and contralateral asymptomatic carotid plaque using noninvasive dynamic contrast‐enhanced magnetic resonance imaging.Methods and ResultsEighty‐eight patients with recent transient ischemic attack or ischemic stroke and ipsilateral >2 mm carotid plaque underwent 3 T magnetic resonance imaging to identify plaque components and to determine characteristics of plaque microvasculature. The volume transfer coefficient K trans, indicative for microvascular density, flow, and permeability, was calculated for the ipsilateral and asymptomatic plaque, using a pharmacokinetic model (Patlak). Presence of a lipid‐rich necrotic core, intraplaque hemorrhage, and a thin and/or ruptured fibrous cap was assessed on multisequence magnetic resonance imaging. We found significantly lower K trans in the symptomatic carotid plaque compared with the asymptomatic side (0.057±0.002 min−1 versus 0.062±0.002 min−1; P=0.033). There was an increased number of slices with intraplaque hemorrhage (0.9±1.6 versus 0.3±0.8, P=0.002) and lipid‐rich necrotic core (1.4±1.9 versus 0.8±1.4, P=0.016) and a higher prevalence of plaques with a thin and/or ruptured fibrous cap (32% versus 17%, P=0.023) at the symptomatic side.Conclusions K trans was significantly lower in symptomatic carotid plaques, indicative for a decrease of plaque microvasculature in symptomatic plaques. This could be related to a larger amount of necrotic tissue in symptomatic plaques.Clinical Trial Registration URL: http://www.clinicaltrials.gov.uk. Unique identifier: NCT01208025.

Virtual monoenergetic dual-energy CT for evaluation of hepatic and splenic lacerations.

To evaluate the utility of virtual monoenergetic imaging in assessing hepatic and splenic lacerations and to determine the optimal energy level to maximize injury contrast-to-noise ratio. We retrospectively examined 49 contrast-enhanced abdominal CT studies performed on a dual-source dual-energy CT (DECT) scanner with reported liver and/or splenic lacerations. All studies included portal venous phase imaging acquired simultaneously at low (80 or 100kVp) and high (140kVp with tin filtration) energy levels. Conventional 120kVp-equivalent images were generated for routine review by blending the low and high energy acquisitions. Virtual monoenergetic reconstructions were retrospectively generated in 10keV increments from 40 to 90keV. Liver or splenic laceration attenuation, background parenchymal attenuation, and noise were measured on each set of monoenergetic and conventional images. Injury-to-parenchyma contrast and contrast-to-noise ratios (CNR) were calculated. Differences between CNR of monoenergetic series and conventional images were assessed with a paired t test. Liver laceration was identified in 28 patients, and splenic laceration in 22 patients. Background noise was lower at higher monoenergetic levels, with the lowest noise seen at 90keV, less than that of conventional images (stddev 8.0 for 90keV and 8.5 for conventional based on noise of uninjured liver/spleen parenchyma, p < 0.001). For both liver and splenic lacerations, injury-to-parenchyma contrast was greater at lower monoenergetic levels, with maximum at 40keV. Contrast at 40-70keV was significantly greater than that of conventional images (p < 0.001). Injury-to parenchyma CNR was also greater at 40-70keV than that of conventional images and with statistical significance. CNR was highest at 40keV for both liver (6.5 for 40keV and 5.4 for conventional, p < 0.001) and splenic lacerations (7.5 vs. 5.8, p < 0.001). DECT virtual monoenergetic imaging at low keV improves injury-to-parenchyma CNR of hepatic and splenic lacerations compared with traditional polyenergetic reconstructions. Specially, the optimal energy level for assessing both was 40keV.

Quantification of haematomyocardial barrier permeability for polyacetate complexes of Gd in ishaemic and inflammatory myocardial damage

Purpose. We developed and applied for quantification of microvascular permeability in damaged myocardium a model - based approach employing the dynamic acquisition of magnetic resonance imaging of paramagnetic diffusion to damaged myocardium and kinetic Gjedde-Rutlend-Patlak (GRP) analysis of blood clearance of the contrast concomitantly with it’s rise in the damaged tissue, in ischemic or inflamed tissue. Material and methods . The model is based on the passive gradient-driven diffusion, unidirectional for first minutes after injection of the contrast, used as Gjedd-Rutland-Patlak technique. If the C myoc - depicts the concentration of the paramagnetic in the blood, and the C blood -means the blood level of the contrast agent, whereas the k blood–myocardium – is the index of diffusion of the contrast from blood to myocardium, then assuming the diffusion unidirectional for first minutes post injection we can plot the ratio {( ∫ C blood (t)dt ) / C blood } – as abscissa X, and { C myoc / C blood } – as ordinata Y, k blood-myocardium can be obtained then from such linear plot as it’s slope. We substituted the concentrations themselves with the values of intensities of the echo-planar ECG-synchronized scans of the heart and validated this approach with comparison of MRI intensity data over LV cavity to Gd content in blood samples. MRI of the heart with contrast enhancement was carried out using dynamic scannig, after bolus injection of 2 ml of 0.5 M of paramagnetic contrast (Gadoversetamide -TMOptimark) per 10 Kg of BW. TR = 3.4 ms, TE = 1.7 ms, inversion time 176.0 ms, deviation angle = 40 deg, scanning field 38 х 38 cm, slice thickness = 8-10 мм , acqu-sition matrix 256 х 256, or 192 х 192, echo train length = 1. The groups of patients comprised twenty one persons with acute myocardial infarction treated clically successfully with intravenous thrombolysis and coronary stenting and also nine persons with firstly revealed inflammatory myocarditis. Uptake kinetics to the myocardium was imaged using protocols with fat supression for up to 12 minutes after bolus injection and then processed using RadiAnt software (Medixant, Poznan, Polska), and also original software for dynamic data analysis written using MATLAB 6.1 (SCILAB also), with output of plots of MRI signal intensities over time for various myocardial regions and also of GRP plots and calculation of k blood-myocardium values. Results . The physiological sence of the k blood–myocardium diffusion koefficient means this value depicts the clearance of paramagnetic to myocardium, i.e. the amount of blood cleared from the paramagnetic due to paramagnetic’ diffusion to damaged myocardium, per minute, per unit of myocardial volume. The value of the k blood–myocardium diffusion koefficient was, respectively, as high as 3.09 ± 1.32 (2.36-11.9) ml/min/100 g of tissue, in myocardial infarction although treated successfully with thrombolysis and stenting (n = 21) and 1.78 ± 0.67 (0.50-2.42) ml/min/100 g of tissue -in inflammatory myocarditis damage of myocardium (n = 9); In normal controls k blood–myocardium was close to zero values and namely as low as 0.09 ± 0.06 (<0.2) (ml/min/100 g of tissue). Use of this dynamic protocol provided highly significant separation of ishemic and iflammatory conditions. Conclusion . Dynamic MRI echo-planar ECG-synchro-nised contrast-enhanced echo-planar study of the heart can be successfully carried out using both high- and middle-field MRI scanner. The model-based indexes of diffusion of paramagnetic to the infarction or inflammation are significantly different and deliver additional object-based characteristics of the vascular permeability of the damaged haematomyocardial barrier.

SPGR with Contrast-Enhanced versus SE contrast-enhanced T1-weighted studies of the head

SPGR with Contrast-Enhanced versus SE contrast-enhanced T1-weighted studies of the head