Administration Of Contrast Agent Research Articles

#2889 Multiple renal tumors as an atypical clinical manifestation of granulomatosis with polyangiitis

Abstract Background and Aims Granulomatosis with polyangiitis (GPA) is a systemic small- vessel vasculitis associated with antineutrophilic cytoplasmic antibody (ANCA), in which kidney involvement often occurs. In some cases the course of vasculitis with kidney involvement is atypical, what complicates the diagnostic process and makes appropriate treatment difficult. Finding nodular masses in the kidneys always causes an oncological concern, while in the differential diagnosis a systemic vasculitis is rarely taken into account, what may lead to an unnecessary nephrectomy. Method We present a case of granulomatosis with polyangiitis (GPA) who presented with multiple tumors in the kidneys and adrenal gland. Results 29-year-old man experienced a sudden disease onset, at the age of 18 years, when due to peripheral oedema, nephrotic grade proteinuria (13.7 g/24 h), hematuria and presence of renal failure markers (serum creatinine 3.4 mg/dL), he was admitted to hospital. A suggestion of a rapidly progressive glomerulonephritis (RPGN) was put forward and a renal biopsy was performed (in the histopathological examination of the kidney, pauci-immune crescentic necrotizing glomerulonephritis was revealed). A treatment with plasmaphereses, high glucocorticosteroid doses and cyclophosphamide pulses was instituted. Haemodialysis therapy was also applied temporarily. ANCA and anti-glomerular basement membrane (GBM) antibodies were determined to give negative results. As a result of the remission-inducing treatment, an improvement of the renal function was obtained (serum creatinine 1.6-1.9 mg/dL). In spite of the remission-maintaining treatment with mycophenolate mofetil (MMF) and oral prednisone, after 10 years again a dramatic renal function impairment occurred, with a necessity of institution of a long-term haemodialysis therapy. Furthermore, on abdominal ultrasound examination multiple focal lesions were found in both kidneys, which rendered a kidney transplantation procedure in the patient impossible. In order to extend the diagnostic procedures, a magnetic resonance imaging (MRI) of the abdominal cavity without contrast agent administration was carried out (in both kidneys disseminated focal lesions were described: non-homogeneous, with moderately enhanced signal on T2-weighted images in the central part, without signs of water diffusion restriction; in the left kidney, of 23 x 22 mm and 19 x 15 mm dimensions; in the right kidney, of 30 x 32 mm, 26 x 22 mm and 22 x 18 mm dimensions. The picture of the lesions was unspecific and atypical. In the differential diagnosis granulomas could not have been ruled out, while disseminated proliferative lesions were less likely. Besides that, in both kidneys cysts of up to 7 mm diameters were present. In the lateral limb of the left adrenal gland a focal lesion was visible, of 23 x 14 mm dimensions, of a structure identical to that of the foci in both kidneys). On high-resolution computed tomography (HRCT) of the chest at the same time, small ground glass areas were found in the lungs. On positron emission tomography/computed tomography (PET/CT) no changes were visualised, suggesting presence of a metabolically active proliferative process. Tests for ANCA, antinuclear antibodies (ANA), anti- double-stranded DNA (dsDNA) antibodies, anti- GBM antibodies were again performed and gave negative results. He was diagnosed with granulomatosis with polyangiitis without ANCA and treated with corticosteroid and intravenous rituximab (4x 787 mg). Three months later, follow-up showed reduced mass lesions in the kidney and adrenal gland by MRI. Conclusion The case highlights the atypical clinical presentation of vasculitis and the significance of considering this possibility in differential diagnosis when confronting mass lesions present in the kidney.

DILATED CARDIOMYOPATHY, GUIDELINES PERSONALIZATION OF CARE

Abstract The term Dilated cardiomyopathy (CMD) refers to a family of diseases characterized by complex interactions between environment and genetic predisposition. Diagnostic tools as cardiac magnetic resonance imaging (MRI) must be systematically implemented in clinical practice to define the etiological cause and undertake a specific therapeutic treatment. We present the case of a young man with CMD and severe left ventricular dysfunction (ejection fraction, EF: 14%; left ventricular end–diastolic volume (LVEDV): 251 ml/m2; left ventricular end–systolic volume (LVESV): 197 ml/m2. The patient has a family history of sudden cardiac death (SCD). He is affected by a psychiatric pathology (ADHD) and has a history of alcohol and drug addiction. Many diagnostic hypotheses have been considered for etiological research (viral myocarditis, genetic or alcoholic–induced cardiomyopathy, toxic substances such as narcotics and psychiatric drug–induced cardiomyopathy). MRI after 11 days in hospital confirmed FE 14%, LVEDV: 320 ml/m2, LVESV: 275 ml/m2; reduction of the wall thickness at the antero–septal wall to the middle tract; areas of altered signal, hyperintense in T2W sequences, at the left ventricular myocardial wall suspected of myocardial edema, associated with extended signal hyperintensity of periventricular tissue, which show marked enhancement immediately after intravenous contrast agent administration (Fig. 1). The underlying psychiatric pathology and the possibility of poor adherence to the maintenance of the wearable defibrillator did not facilitate the clinical follow–up which should have included the identification of the etiological cause and the appropriate treatment guaranteeing the temporary prevention of SCD. So, it was decided to make a personalized therapeutic choice, the patient underwent implantation of a subcutaneous defibrillator, pending a better diagnostic definition and the possible need of other therapies as cardiac transplantation/implantation of mechanical assistance device.

Estimating the volume of penumbra in rodents using DTI and stack-based ensemble machine learning framework

BackgroundThis study investigates the potential of diffusion tensor imaging (DTI) in identifying penumbral volume (PV) compared to the standard gadolinium-required perfusion–diffusion mismatch (PDM), utilizing a stack-based ensemble machine learning (ML) approach with enhanced explainability.MethodsSixteen male rats were subjected to middle cerebral artery occlusion. The penumbra was identified using PDM at 30 and 90 min after occlusion. We used 11 DTI-derived metrics and 14 distance-based features to train five voxel-wise ML models. The model predictions were integrated using stack-based ensemble techniques. ML-estimated and PDM-defined PVs were compared to evaluate model performance through volume similarity assessment, the Pearson correlation analysis, and Bland–Altman analysis. Feature importance was determined for explainability.ResultsIn the test rats, the ML-estimated median PV was 106.4 mL (interquartile range 44.6–157.3 mL), whereas the PDM-defined median PV was 102.0 mL (52.1–144.9 mL). These PVs had a volume similarity of 0.88 (0.79–0.96), a Pearson correlation coefficient of 0.93 (p < 0.001), and a Bland–Altman bias of 2.5 mL (2.4% of the mean PDM-defined PV), with 95% limits of agreement ranging from -44.9 to 49.9 mL. Among the features used for PV prediction, the mean diffusivity was the most important feature.ConclusionsOur study confirmed that PV can be estimated using DTI metrics with a stack-based ensemble ML approach, yielding results comparable to the volume defined by the standard PDM. The model explainability enhanced its clinical relevance. Human studies are warranted to validate our findings.Relevance statementThe proposed DTI-based ML model can estimate PV without the need for contrast agent administration, offering a valuable option for patients with kidney dysfunction. It also can serve as an alternative if perfusion map interpretation fails in the clinical setting.Key points• Penumbral volume can be estimated by DTI combined with stack-based ensemble ML.• Mean diffusivity was the most important feature used for predicting penumbral volume.• The proposed approach can be beneficial for patients with kidney dysfunction.Graphical

Inferior Frontal Sulcal Hyperintensity on Fluid-Attenuated Inversion Recovery Is Related to Cerebrospinal Fluid Clearance via Putative Meningeal Lymphatics.

Inferior frontal sulcal hyperintensity (IFSH) on FLAIR sequence may indicate elevated cerebrospinal fluid (CSF) wastes. The objective of this study was to investigate its association with the clearance function of putative meningeal lymphatic vessels (mLVs). We included patients who underwent FLAIR sequence and dynamic contrast MRI with intrathecal administration of contrast agent. The visibility of IFSH was quantitatively assessed by measuring the mean signal intensity of inferior frontal sulci on 2D FLAIR. The clearance function of putative mLVs was defined as the percentage change of signal unite ratio in the parasagittal dura from baseline to 4.5, 15 and 39 hours after intrathecal injection on dynamic contrast MRI. Additionally, imaging markers of cerebral small vessel disease, including white matter hyperintensities and enlarged perivascular spaces, were measured. Correlation analysis and linear regression were employed to verify the association of IFSH with the clearance function of mLVs. A total of 76 patients were included in the study. The visibility of IFSH was found to be associated with the percentage change of signal unite ratio in parasagittal dura from baseline to 15 and 39 hours in adjusted analyses. Furthermore, the visibility of IFSH was positively related to the age, scores of both periventricular and deep white matter hyperintensities, and the grade of enlarged perivascular spaces in centrum semiovale. These findings suggest that the visibility of IFSH on 2D FLAIR may serve as an indicator of clearance dysfunction of mLVs and may be implicated in the development of cerebral small vessel disease.

Association of urgent transcatheter aortic valve replacement (TAVR) with acute kidney injury 30-days post-TAVR: a systematic review and meta-analysis

Abstract Funding Acknowledgements None. Introduction Recent studies have proven that TAVR is a viable treatment option for symptomatic aortic stenosis (AS), regardless of surgical risk, even though, there are certain significant hazards associated with it. Even with the improvements in technique and experience, peri- and post-procedural complications like acute kidney injury (AKI) continue to occur frequently and are recognized for their serious clinical implications in the setting of TAVR. The vast majority of TAVR procedures conducted across the US are elective procedures on patients who are hemodynamically stable. Nonetheless, published data, imply that urgent TAVR, despite higher mortality rates is a feasible option to treat decompensated severe aortic valve stenosis. Purpose The aim of this systematic review and meta-analysis is to assess AKI in patients 30-days after an urgent TAVR and compare them with the elective TAVR population. Methods This meta-analysis adhered to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A comprehensive database search was conducted using three major databases (Medline, Cochrane Central Register of Controlled Trials and Scopus) for studies comparing patients submitted to urgent versus elective TAVR. Primary endpoint of our systematic review and meta-analysis is the AKI 30-days after TAVR. Only studies provided data about our primary endpoint were considered in the analysis. Secondary endpoints included myocardial infarction (MI), permanent pacemaker implantation (PPM) and bleeding events during the first 30-days post-procedurally. Risk ratio (RR) was calculated with 95% confidence intervals (CIs) and a random-effects model (Mantel-Haenzel) was used to estimate the pooled RR. Results A total of 16 studies with 101,568 patients were added in our analysis. Among them, 16,349 patients underwent an urgent TAVR, while the rest 85,219 had an elective procedure. Our analysis showed that patients submitted to urgent TAVR have 258% higher risk for AKI during the first 30-days post-procedurally (RR: 2.58, 95%CI: 1.98, 3.37) (Figure). Data about the 30-days MI, PPM and bleeding events were available for 9, 15 and 11 studies, respectively. The risk for MI appeared to be significantly higher in patients undergone urgent TAVR (RR: 5.49, 95% CI: 1.76, 17.05), while the risk for bleeding events was slightly higher in the same group (RR: 1.39, 95% CI: 1.14, 1.70). No significant differences were observed in PPM incidence (RR: 1.05, 95%CI: 1.00, 1.11) during 30-days follow-up. Conclusion In this systematic review and meta-analysis, patients undergoing urgent TAVR procedures compared to elective procedures have increased risk for AKI during the first 30-days post-TAVR. Thus, when urgent TAVR is performed risk factors for AKI should be evaluated and proper renal protection measures, such as adequate hydration and minimal contrast agent administration, should be implemented. Further research in this area is warranted.

Evaluation of the Contrast Enhancement Performance of Gadopiclenol for Magnetic Resonance Angiography in Healthy Rabbits and Pigs.

Unexpected accumulations of gadolinium in various organs were reported after the administration of gadolinium-based contrast agents, making desirable to reduce the dose while maintaining equivalent diagnostic performance. The aim of this study was to evaluate the contrast enhancement performance of high relaxivity gadopiclenol compared with gadoterate meglumine in abdominal contrast-enhanced magnetic resonance angiography (CE-MRA). In a first study in healthy rabbits, axial 3D gradient echo sequences were applied at 4.7 T to study arterial enhancement as a function of gadopiclenol dose (0.025, 0.05, 0.075, and 0.1 mmol Gd/kg) or gadoterate meglumine at 0.1 mmol Gd/kg (n = 5-6/group). The increase in signal-to-noise ratio (ΔSNR) in the aorta at the first pass was measured and compared. In a second, crossover study in 6 healthy pigs, abdominal CE-MRA sequences were acquired at 3 T with gadopiclenol at 0.05 mmol Gd/kg or gadoterate meglumine at 0.1 mmol Gd/kg at a 1-week interval. Quantitatively on the maximum intensity projection (MIP) images, the mean MIP SNR within the aorta of both groups was compared. Qualitatively, a blinded comparison of the angiograms was performed by an experienced radiologist to determine the preferred contrast agent. In the rabbit, ∆SNR is linearly correlated with the gadopiclenol dose (P = 0.0010). Compared with gadoterate meglumine 0.1 mmol Gd/kg, an increase in the ∆SNR is observed after 0.05, 0.075, and 0.1 mmol Gd/kg of gadopiclenol (+63% P = 0.0731, +78% P = 0.0081, and +72% P = 0.0773, respectively), whereas at 0.025 mmol Gd/kg, ∆SNR is in the same range as with gadoterate meglumine 0.1 mmol Gd/kg (+15% P > 0.9999). In pigs, contrast enhancement after gadopiclenol at 0.05 mmol/kg is +22% superior to MIP SNR after gadoterate meglumine at 0.1 mmol Gd/kg (P = 0.3095). Qualitatively, a preference was shown for gadopiclenol images (3/6) over the gadoterate meglumine examinations (1/6), with no preference being shown for the remainder (2/6). First-pass CE-MRA is feasible with gadopiclenol at 0.05 mmol Gd/kg with at least the same arterial signal enhancement and image quality as gadoterate meglumine at 0.1 mmol Gd/kg.

Abstract PS05-08: Restriction Spectrum Imaging MRI for automated evaluation of response to neoadjuvant therapy in breast cancer

Abstract Introduction: Dynamic contrast-enhanced MRI (DCE) is currently used to evaluate neoadjuvant therapy response of breast cancer (1). However, DCE requires expert radiologist readers to assess the change in longest tumor dimension during therapy, as well as administration of Gadolinium contrast agents. One MRI modality that does not require contrast agents is diffusion-weighted MRI (DWI), a method that detects the microscopic diffusion of water molecules. However, the commonly used DWI method apparent diffusion coefficient (ADC) is not fully optimised in the breast (2). The purpose of the current study was to evaluate the recent DWI method Restriction Spectrum Imaging (RSI) (2) to automatically monitor breast tumor size during neoadjuvant therapy. Methods: Twenty-seven women underwent 3T MRI at four time points during therapy at University of California San Diego; 17 received all four scans (see Table 1 for patient details). Inclusion criteria included biopsy-proven unilateral invasive breast cancer ≥2.5 cm (defined on clinical examination/imaging) with indication for neoadjuvant therapy. The therapy used was primarily paclitaxel (+/-experimental agent) followed by anthracycline. The MRI protocol included Gadolinium DCE and DWI (b-values 0, 500, 1500, 4000 s/mm2); TE/TR = 82/9000 ms. ADC was calculated using b-values &amp;lt; 1000 s/mm2 while signal from all available b-values were fitted to the previously-developed three-component RSI model (2). The tumor size by RSI was assessed against manual DCE tumor size and mean ADC values. Prediction of therapy response during therapy and residual tumor post-therapy were assessed using non-pathological complete response (non-pCR) as endpoint. pCR was defined as ypT0/is or ypN0. Results: Ten patients experienced pCR. Prediction of non-pCR by ROC AUC at the early-therapy time point was 0.65 for RSI, 0.64 for DCE and 0.45 for ADC (Table 2). Prediction of post-therapy residual tumor is given in Table 3. Discussion: The novel RSI cancer tissue classifier predicted response to neoadjuvant therapy after only 19 days. RSI could also identify 71% of cases with residual tumor at surgery with 90% specificity post-therapy. RSI performance was similar to performance by standard MRI by manual tumor measurement on DCE. In contrast to standard-of-care MRI by using DCE and ADC that requires manual user input, the RSI classifier is automatic. This suggests that RSI may aid to cost-efficiently evaluate neoadjuvant therapy of breast cancer, with the aim to help guide clinical decision-making and enable tailored therapy regimens.

Clinical implementation of a fully automated quantitative perfusion cardiovascular magnetic resonance imaging workflow with a simplified dual-bolus contrast administration scheme

This study clinically implemented a ready-to-use quantitative perfusion (QP) cardiovascular magnetic resonance (QP CMR) workflow, encompassing a simplified dual-bolus gadolinium-based contrast agent (GBCA) administration scheme and fully automated QP image post-processing. Twenty-five patients with suspected obstructive coronary artery disease (CAD) underwent both adenosine stress perfusion CMR and an invasive coronary angiography or coronary computed tomography angiography. The dual-bolus protocol consisted of a pre-bolus (0.0075 mmol/kg GBCA at 0.5 mmol/ml concentration + 20 ml saline) and a main bolus (0.075 mmol/kg GBCA at 0.5 mmol/ml concentration + 20 ml saline) at an infusion rate of 3 ml/s. The arterial input function curves showed excellent quality. Stress MBF ≤ 1.84 ml/g/min accurately detected obstructive CAD (area under the curve 0.79; 95% Confidence Interval: 0.66 to 0.89). Combined visual assessment of color pixel QP maps and conventional perfusion images yielded a diagnostic accuracy of 84%, sensitivity of 70% and specificity of 93%. The proposed easy-to-use dual-bolus QP CMR workflow provides good image quality and holds promise for high accuracy in diagnosis of obstructive CAD. Implementation of this approach has the potential to serve as an alternative to current methods thus increasing the accessibility to offer high-quality QP CMR imaging by a wide range of CMR laboratories.

Spontaneous intracranial hypotension: Exploring the viability of non-contrast FLAIR as a substitute for contrast-enhanced T1WI in assessing pachymeningeal thickening.

To avoid contrast administration in spontaneous intracranial hypotension (SIH), some studies suggest accepting diffuse pachymeningeal hyperintensity (DPMH) on non-contrast fluid-attenuated inversion recovery (FLAIR) as an equivalent sign to diffuse pachymeningeal enhancement (DPME) on contrast-enhanced T1WI (T1ce), despite lacking thoroughperformance metrics. This study aimed to comprehensively explore its feasibility. In this single-center retrospective study, between April 2021 and November 2023, brain MRI examinations of 43 patients clinically diagnosed with SIH were assessed using 1.5 and 3.0 Tesla MRI scanners. Two radiologists independentlyassessed the presence or absence of DPMH on FLAIR and DPME on T1ce, with T1ce serving as a gold-standard for pachymeningeal thickening. The contribution of the subdural fluid collections to DPMH was investigated with quantitative measurements. Using Cohen's kappa statistics, interobserver agreement was assessed. In 39 out of 43 patients (90.7%), pachymeningeal thickening was observed on T1ce. FLAIR sequence produced an accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 72.1%, 71.8%, 75.0%, 96.6%, and 21.4% respectively, for determining pachymeningeal thickening. FLAIR identified pachymeningeal thickening in 28 cases; however, among these, 21 cases (75%) revealed that the pachymeningeal hyperintense signal was influenced by subdural fluid collections. False-negative rate for FLAIR was 28.2% (11/39). The lack of complete correlation between FLAIR and T1ce in identifying pachymeningeal thickening highlights the need for caution in removing contrast agent administration from the MRI protocol of SIH patients, as it reveals a major criterion (i.e., pachymeningeal enhancement) of Bern score.

Spontaneous isolated gastric intramural hematoma combined with spontaneous superior mesenteric artery intermural hematoma: a rare case

BackgroundGastric intramural hematoma is a rare disease. Here we report a case of spontaneous isolated gastric intramural hematoma combined with spontaneous superior mesenteric artery intermural hematoma.Case presentationA 75-years-old man was admitted to our department with complaints of abdominal pain. He underwent a whole abdominal computed tomography (CT) scan in the emergency department, which showed extensive thickening of the gastric wall in the gastric body and sinus region with enlarged surrounding lymph nodes, localized thickening of the intestinal wall in the transverse colon, localized indistinct demarcation between the stomach and transverse colon, and a small amount of fluid accumulation in the abdominal cavity. Immediately afterwards, he was admitted to our department, and then we arranged a computed tomography with intravenously administered contrast agent showed a spontaneous isolated gastric intramural hematoma combined with spontaneous superior mesenteric artery intermural hematoma. Therefore, we treated him with anticoagulation and conservative observation. During his stay in the hospital, he was given low-molecular heparin by subcutaneous injection for anticoagulation therapy, and after discharge, he was given oral anticoagulation therapy with rivaroxaban. At the follow-up of more than 4 months, most of the intramural hematoma was absorbed and became significantly smaller, and the intermural hematoma of the superior mesenteric artery was basically absorbed, which also confirmed that the intramural mass was an intramural hematoma.ConclusionA gastric intramural hematoma should be considered, when an intra-abdominal mass was found to be attached to the gastric wall. Proper recognition of gastric intramural hematoma can reduce the misdiagnosis rate of confusion with gastric cancer.

Deep learning for discrimination of active and inactive lesions in multiple sclerosis using non-contrast FLAIR MRI: A multicenter study

BackgroundWithin the domain of multiple sclerosis (MS), the precise discrimination between active and inactive lesions bears immense significance. Active lesions are enhanced on T1-weighted MRI images after administration of gadolinium-based contrast agents, which brings about associated complexities. This study investigates the potential of deep learning to differentiate between active and inactive lesions in MS using non-contrast FLAIR-type MRI data, presenting a non-invasive alternative to conventional gadolinium-based MRI methods. MethodsThe dataset encompasses 9097 lesion images collected from 130 MS patients across four distinct imaging centers, with post-contrast T1-weighted images as the benchmark reference. We initially identified and labeled the lesions and carefully selected corresponding regions of interest (ROIs). These ROIs were employed as inputs for a convolutional neural network (CNN) to predict lesion status. Also, transfer learning was utilized, incorporating 12 pre-trained CNN models. Subsequently, an ensemble technique was applied to 3 of best models, followed by a systematic comparison of the results. ResultsThrough a 5-fold cross-validation, our custom designed network exhibited an average accuracy of 85 %, a sensitivity of 95 %, a specificity of 75 %, and an AUC value of 0.90. Among the pre-trained models, ResNet50 emerged as the most effective, achieving a specificity of 58 %, an accuracy of 75 %, a sensitivity of 91 %, and an AUC value of 0.81. Our comprehensive evaluations encompassed the receiver operating characteristic curve, precision-recall curve, and confusion matrix analyses. ConclusionThe findings underscore the efficacy of the proposed CNN, trained on FLAIR MRI data ROIs, in accurately discerning active and inactive lesions without reliance on contrast agents. Our multicenter study of 130 patients with diverse imaging devices outperforms the other single-center studies, achieving superior sensitivity and specificity. Unlike studies using multiple modalities, our exclusive use of FLAIR images streamlines the process, and our streamlined approach, excluding conventional pre-processing, demonstrates efficiency. The external validation conducted on diverse datasets, coupled with the analysis of dilated masks, underscores the adaptability and efficacy of our custom CNN model in discerning between active and inactive lesions.

Prospects of perfusion contrast-enhanced ultrasound (CE-US) in diagnosing axillary lymph node metastases in breast cancer: a comparison with lymphatic CE-US.

Accurate diagnosis of lymph node (LN) metastasis is vital for prognosis and treatment in patients with breast cancer. Imaging 1modalities such as ultrasound (US), MRI, CT, and 18F-FDG PET/CT are used for preoperative assessment. While conventional US is commonly recommended due to its resolution and sensitivity, it has limitations such as operator subjectivity and difficulty detecting small metastases. This review shows the microanatomy of axillary LNs to enhance accurate diagnosis and the characteristics of contrast-enhanced US (CE-US), which utilizes intravascular microbubble contrast agents, making it ideal for vascular imaging. A significant focus of this review is on distinguishing between two types of CE-US techniques for axillary LN evaluation: perfusion CE-US and lymphatic CE-US. Perfusion CE-US is used to assess LN metastasis via transvenous contrast agent administration, while lymphatic CE-US is used to identify sentinel LNs and diagnose LN metastasis through percutaneous contrast agent administration. This review also highlights the need for future research to clarify the distinction between studies involving "apparently enlarged LNs" and "clinical node-negative" cases in perfusion CE-US research. Such research standardization is essential to ensure accurate diagnostic performance in various clinical studies. Future studies should aim to standardize CE-US methods for improved LN metastasis diagnosis, not only in breast cancer but also across various malignancies.

Regression of Endolymphatic Hydrops in Patient With Meniere's Disease Treated With Vestibular Neurectomy: A Case Report.

Vestibular neurectomy is an effective method eliminating vertigo attacks in patients suffering from disabling Meniere's disease with no clinical improvement despite conservative and intratympanic therapy. Magnetic resonance imaging allows in vivo evaluation of changes manifesting in the inner ear after treatment; however, downgrading of the endolymphatic hydrops after vestibular neurectomy had not been previously described in the literature. In the present article, a case of a patient with unilateral severe Meniere's disease treated with selective vestibular nerve section from middle fossa approach was described. Clinical symptoms and audiovestibular tests were evaluated before and 13 months after the surgery. Complete resolution of vertigo episodes and hearing preservation was achieved. Magnetic resonance imaging was performed before and after the surgery using a 3 Tesla scanner with dedicated protocol after intravenous administration of gadolinium contrast agent. In the follow-up examination, regression of the cochlear and vestibular endolymphatic hydrops was visualized, which may suggest processes occurring in the labyrinth as a result of the vestibular efferent fibers section.

Assessment of arterial blood flow in the microvasculature of the lower extremities in patients with chronic ischemia using a single-photon emission computed tomography (SPECT)

Introduction. Obliterating atherosclerosis of the lower extremity vessels is a chronic, steadily progressive disease of the leg arteries, with a high risk of limb amputation and death. Timely diagnosis and adequate treatment will help slow the disease progression, maintain the patient’s good health for a long time and avoid complications. Purpose. To study arterial blood flow in the microvasculature of the lower extremities, to qualitatively and quantitatively assess perfusion disturbances in functionally significant muscles of the lower extremities. Material and methods. Radionuclide examination of the main vessels and microvasculature of the lower extremities was performed in 36 patients, five of them with a diagnosis of lower extremity obliterating atherosclerosis in dynamics. Radiopharmaceuticals was administered through a catheter installed endovascularly above the aortic bifurcation when patients underwent arteriography of the lower extremity vessels, which also involves intra-arterial administration of a radiopaque contrast agent. Results. When processing the radiological study results, we visually assessed the distribution of radiopharmaceuticals in the vascular bed of the lower extremities, identified the asymmetry in the accumulation of radiopharmaceuticals as a percentage, quantified the accumulation of radiopharmaceutical pulses in the projection of the pelvic, thigh, leg and foot muscles, determining the level of accumulation in each of the areas of interest as a percentage. The radiological study results and direct aortic arteriography of the lower extremities with determination of the level of arterial stenosis confirmed the ischemic nature of the pain syndrome; and in the control study, the effectiveness of treatment with an improvement in perfusion parameters. Conclusions. Intra-arterial administration of radiopharmaceuticals makes it possible to assess the condition of the peripheral arterial bed, which has a significant role in the prognosis of lower extremity atherosclerosis and the results of reconstructive interventions. The method makes possible a hybrid topometric comparison of arterio-perfusion maps for diagnosis, planned treatment and monitoring of its results in dynamics.

An update on susceptibility-weighted imaging in brain gliomas.

Susceptibility-weighted imaging (SWI) has become a standard component of most brain MRI protocols. While traditionally used for detecting and characterising brain hemorrhages typically associated with stroke or trauma, SWI has also shown promising results in glioma assessment. Numerous studies have highlighted SWI's role in differentiating gliomas from other brain lesions, such as primary central nervous system lymphomas or metastases. Additionally, SWI aids radiologists in non-invasively grading gliomas and predicting their phenotypic profiles. Various researchers have suggested incorporating SWI as an adjunct sequence for predicting treatment response and for post-treatment monitoring. A significant focus of these studies is on the detection of intratumoural susceptibility signals (ITSSs) in gliomas, which are indicative of microhemorrhages and vessels within the tumour. The quantity, distribution, and characteristics of these ITSSs can provide radiologists with more precise information for evaluating and characterising gliomas. Furthermore, the potential benefits and added value of performing SWI after the administration of gadolinium-based contrast agents (GBCAs) have been explored. This review offers a comprehensive, educational, and practical overview of the potential applications and future directions of SWI in the context of glioma assessment. CLINICAL RELEVANCE STATEMENT: SWI has proven effective in evaluating gliomas, especially through assessing intratumoural susceptibility signal changes, and is becoming a promising, easily integrated tool in MRI protocols for both pre- and post-treatment assessments. KEY POINTS: • Susceptibility-weighted imaging is the most sensitive sequence for detecting blood and calcium inside brain lesions. • This sequence, acquired with and without gadolinium, helps with glioma diagnosis, characterisation, and grading through the detection of intratumoural susceptibility signals. • There are ongoing challenges that must be faced to clarify the role of susceptibility-weighted imaging for glioma assessment.

Comparison of MRI Sequences to Predict IDH Mutation Status in Gliomas Using Radiomics-Based Machine Learning.

Regarding the 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumors, the isocitrate dehydrogenase (IDH) mutation status is one of the most important factors for CNS tumor classification. The aim of our study is to analyze which of the commonly used magnetic resonance imaging (MRI) sequences is best suited to obtain this information non-invasively using radiomics-based machine learning models. We developed machine learning models based on different MRI sequences and determined which of the MRI sequences analyzed yields the highest discriminatory power in predicting the IDH mutation status. In our retrospective IRB-approved study, we used the MRI images of 106 patients with histologically confirmed gliomas. The MRI images were acquired using the T1 sequence with and without administration of a contrast agent, the T2 sequence, and the Fluid-Attenuated Inversion Recovery (FLAIR) sequence. To objectively compare performance in predicting the IDH mutation status as a function of the MRI sequence used, we included only patients in our study cohort for whom MRI images of all four sequences were available. Seventy-one of the patients had an IDH mutation, and the remaining 35 patients did not have an IDH mutation (IDH wild-type). For each of the four MRI sequences used, 107 radiomic features were extracted from the corresponding MRI images by hand-delineated regions of interest. Data partitioning into training data and independent test data was repeated 100 times to avoid random effects associated with the data partitioning. Feature preselection and subsequent model development were performed using Random Forest, Lasso regression, LDA, and Naïve Bayes. The performance of all models was determined with independent test data. Among the different approaches we examined, the T1-weighted contrast-enhanced sequence was found to be the most suitable for predicting IDH mutations status using radiomics-based machine learning models. Using contrast-enhanced T1-weighted MRI images, our seven-feature model developed with Lasso regression achieved a mean area under the curve (AUC) of 0.846, a mean accuracy of 0.792, a mean sensitivity of 0.847, and a mean specificity of 0.681. The administration of contrast agents resulted in a significant increase in the achieved discriminatory power. Our analyses show that for the prediction of the IDH mutation status using radiomics-based machine learning models, among the MRI images acquired with the commonly used MRI sequences, the contrast-enhanced T1-weighted images are the most suitable.

Automatic Active Lesion Tracking in Multiple Sclerosis Using Unsupervised Machine Learning.

Identifying active lesions in magnetic resonance imaging (MRI) is crucial for the diagnosis and treatment planning of multiple sclerosis (MS). Active lesions on MRI are identified following the administration of Gadolinium-based contrast agents (GBCAs). However, recent studies have reported that repeated administration of GBCA results in the accumulation of Gd in tissues. In addition, GBCA administration increases health care costs. Thus, reducing or eliminating GBCA administration for active lesion detection is important for improved patient safety and reduced healthcare costs. Current state-of-the-art methods for identifying active lesions in brain MRI without GBCA administration utilize data-intensive deep learning methods. To implement nonlinear dimensionality reduction (NLDR) methods, locally linear embedding (LLE) and isometric feature mapping (Isomap), which are less data-intensive, for automatically identifying active lesions on brain MRI in MS patients, without the administration of contrast agents. Fluid-attenuated inversion recovery (FLAIR), T2-weighted, proton density-weighted, and pre- and post-contrast T1-weighted images were included in the multiparametric MRI dataset used in this study. Subtracted pre- and post-contrast T1-weighted images were labeled by experts as active lesions (ground truth). Unsupervised methods, LLE and Isomap, were used to reconstruct multiparametric brain MR images into a single embedded image. Active lesions were identified on the embedded images and compared with ground truth lesions. The performance of NLDR methods was evaluated by calculating the Dice similarity (DS) index between the observed and identified active lesions in embedded images. LLE and Isomap, were applied to 40 MS patients, achieving median DS scores of 0.74 ± 0.1 and 0.78 ± 0.09, respectively, outperforming current state-of-the-art methods. NLDR methods, Isomap and LLE, are viable options for the identification of active MS lesions on non-contrast images, and potentially could be used as a clinical decision tool.

Evidence for interictal blood-brain barrier dysfunction in people with epilepsy.

Interictal blood-brain barrier dysfunction in chronic epilepsy has been demonstrated in animal models and pathological specimens. Ictal blood-brain barrier dysfunction has been shown in humans invivo using an experimental quantitative magnetic resonance imaging (MRI) protocol. Here, we hypothesized that interictal blood-brain barrier dysfunction is also present in people with drug-resistant epilepsy. Thirty-nine people (21 females, mean age at MRI ± SD = 30 ± 8 years) with drug-resistant epilepsy were prospectively recruited and underwent interictal T1-relaxometry before and after administration of a paramagnetic contrast agent. Likewise, quantitative T1 was acquired in 29 people without epilepsy (12 females, age at MRI = 48 ± 18 years). Quantitative T1 difference maps were calculated and served as a surrogate imaging marker for blood-brain barrier dysfunction. Values of quantitative T1 difference maps inside hemispheres ipsilateral to the presumed seizure onset zone were then compared, on a voxelwise level and within presumed seizure onset zones, to the contralateral side of people with epilepsy and to people without epilepsy. Compared to the contralateral side, ipsilateral T1 difference values were significantly higher in white matter (corrected p < .05), gray matter (uncorrected p < .05), and presumed seizure onset zones (p = .04) in people with epilepsy. Compared to people without epilepsy, significantly higher T1 difference values were found in the anatomical vicinity of presumed seizure onset zones (p = .004). A subgroup of people with hippocampal sclerosis demonstrated significantly higher T1 difference values in the ipsilateral hippocampus and in regions strongly interconnected with the hippocampus compared to people without epilepsy (corrected p < .01). Finally, z-scores reflecting the deviation of T1 difference values within the presumed seizure onset zone were associated with verbal memory performance (p = .02) in people with temporal lobe epilepsy. Our results indicate a blood-brain barrier dysfunction in drug-resistant epilepsy that is detectable interictally invivo, anatomically related to the presumed seizure onset zone, and associated with cognitive deficits.

Targeted irradiation in an autochthonous mouse model of pancreatic cancer.

The value of radiotherapy in the treatment of pancreatic cancer has been the subject of much debate but limited preclinical research. We hypothesise that the poor translation of radiation research into clinical trials of radiotherapy in pancreatic cancer is due, in part, to inadequate preclinical study models. Here, we developed and refined methods for targeted irradiation in autochthonous mouse models of pancreatic cancer, using a small animal radiotherapy research platform. We tested and optimised strategies for administration of contrast agents, iohexol and the liver imaging agent Fenestra LC, to enable the use of computed tomography imaging in tumour localisation. We demonstrate accurate tumour targeting, negligible off-target effects and therapeutic efficacy, depending on dose, number of fractions and tumour size, and provide a proof of concept that precise radiation can be delivered effectively to mouse pancreatic tumours with a clinically relevant microenvironment. This advance will allow investigation of the radiation response in murine pancreatic cancer, discovery of mechanisms and biomarkers of radiosensitivity or resistance, and development of radiosensitising strategies to inform clinical trials for precision radiotherapy in this disease.

Development of A Micro-CT Scanner with Dual-Energy Option and Endovascular Contrast Agent Administration Protocol for Fetal and Neonatal Virtual Autopsy.

The rate of parental consent for fetal and perinatal autopsy is decreasing, whereas parents are more likely to agree to virtual autopsy by non-invasive imaging methods. Fetal and perinatal virtual autopsy needs high-resolution and good soft-tissue contrast for investigation of the cause of death and underlying trauma or pathology in fetuses and stillborn infants. This is offered by micro-computed tomography (CT), as opposed to the limited resolution provided by clinical CT scanners, and this is one of the most promising tools for non-invasive perinatal postmortem imaging. We developed and optimized a micro-CT scanner with a dual-energy imaging option. It is dedicated to post-mortem CT angiography and virtual autopsy of fetuses and stillborn infants in that the chamber can be cooled down to around 5 °C; this increases tissue rigidity and slows decomposition of the native specimen. This, together with the dedicated gantry-based architecture, attempts to reduce potential motion artifacts. The developed methodology is based on prior endovascular injection of a BaSO4-based contrast agent. We explain the design choices and considerations for this scanner prototype. We give details of the treatment of the optimization of the dual-energy and virtual mono-energetic imaging option that has been based on minimizing noise propagation and maximizing the contrast-to-noise ratio for vascular features. We demonstrate the scanner capabilities with proof-of-concept experiments on phantoms and stillborn piglets.