Gadolinium deposition within the dentate nucleus and globus pallidus after repeated administrations of gadolinium-based contrast agents-current status

A Multifunctional Nanodrug Increases the Therapeutic Sensitivity of Lenvatinib to Hepatocellular Carcinoma by Inhibiting the Stemness of Hepatic Cancer Stem Cells

Drug resistance resulting from diverse mechanisms including the presence of cancer stem cells (CSCs) is the main obstacle for improving therapeutic efficacy of lenvatinib in hepatocellular carcinoma (HCC). Herein, a nanomedicine (siCD24-Len-MnO@PLAP) is developed by incorporating manganese oxide (MnO), lenvatinib (Len), and siRNA against CD24 (siCD24) into micelles composed of methoxypolyethylene glycol (mPEG), poly-L-lysine (PLLys), and polyasparagyl(N-(2-Aminoethyl)piperidine) (PAsp(PIP)) triblock copolymer. The nanomedicine can respond to the tumor microenvironment (TME) to release lenvatinib, and produce Mn2+ and O2, accompanied by changes in nanoparticle charge, which facilitates cellular endocytosis of siCD24-loaded nanoparticles. The released siCD24 and lenvatinib synergistically reduces CD24 expression, resulting in a more pronounced inhibition of stemness of CSCs. In the mouse models of HCC using Huh7-derived CSCs and Hepa1-6-derived CSCs, the nanomedicine shows remarkable anti-cancer effect by enhancing the therapeutic effects of lenvatinib against HCC via reducing the expression level of CD24 and decreasing the expression of hypoxia inducible factor-1α (HIF-1α). Moreover, in situ production of paramagnetic Mn2+ from the nanomedicine serves as an excellent contrast agent for magnetic resonance imaging (MRI) to monitor the therapeutic process. This study demonstrates that this multifunctional MRI-visible siCD24- and lenvatinib-loaded nanodrug holds great potential in enhancing therapeutic sensitivity for HCC lenvatinib therapy.

Biocompatible and bioactivable terpolymer-lipid-MnO2 Nanoparticle-based MRI contrast agent for improving tumor detection and delineation

Early and precise detection of solid tumor cancers is critical for improving therapeutic outcomes. In this regard, magnetic resonance imaging (MRI) has become a useful tool for tumor diagnosis and image-guided therapy. However, its effectiveness is limited by the shortcomings of clinically available gadolinium-based contrast agents (GBCAs), i.e. poor tumor penetration and retention, and safety concerns. Thus, we have developed a novel nanoparticulate contrast agent using a biocompatible terpolymer and lipids to encapsulate manganese dioxide nanoparticles (TPL-MDNP). The TPL-MDNP accumulated in tumor tissue and produced paramagnetic Mn2+ ions, enhancing T1-weight MRI contrast via the reaction with H2O2 rich in the acidic tumor microenvironment. Compared to the clinically used GBCA, Gadovist®1.0, TPL-MDNP generated stronger T1-weighted MR signals by over 2.0-fold at 30 % less of the recommended clinical dose with well-defined tumor delineation in preclinical orthotopic tumor models of brain, breast, prostate, and pancreas. Importantly, the MRI signals were retained for 60 min by TPL-MDNP, much longer than Gadovist®1.0. Biocompatibility of TPL-MDNP was evaluated and found to be safe up to 4-fold of the dose used for MRI. A robust large-scale manufacturing process was developed with batch-to-batch consistency. A lyophilization formulation was designed to maintain the nanostructure and storage stability of the new contrast agent.

Imaging of Hepatobiliary Cancer

The liver and biliary tree are common sites of primary and secondary malignancies. MRI followed by CT is the mainstay for the imaging characterization of these malignancies with the dynamically acquired contrast enhanced phases being the most important for diagnosis. The liver imaging reporting and data system classification provides a useful framework for reporting lesions in patents with underlying cirrhosis or who are at high risk for developing hepatocellular carcinoma. Detection of metastases is improved with the use of liver specific MRI contrast agents and diffusion weighted sequences. Aside from hepatocellular carcinoma, which is often diagnosed noninvasively, other primary hepatobiliary tumors may require biopsy for definite diagnosis, especially when presenting with nonclassic imaging findings. In this review, we examine the imaging findings of common and less common hepatobiliary tumors.

Intravoxel incoherent motion (IVIM) MRI in pediatric patients with synovitis of the knee joint: a prospective pilot study

BACKGROUND

Diagnosing synovial inflammation by administration of gadolinium-based contrast agents is limited by invasiveness and possible side effects, especially in children and adolescents.

PURPOSE

We investigated diagnostic accuracy of diffusion-weighted (DWI) MRI with intravoxel incoherent motion (IVIM) imaging compared to contrast-enhanced MRI for detecting synovitis of the knee in a population of pediatrics and young adults. In addition we compared quantitative measures of synovial diffusion and perfusion to a group of healthy volunteers.

METHODS

In this prospective study, 8 pediatric patients with 10 symptomatic knees (6 girls and 2 boys, mean age 13 years) with known or suspected synovitis underwent pre- and post-contrast 3.0 T MRI of the knee joint and additional DWI sequences between October 2016 and July 2019. For comparison we enrolled 5 healthy young adults (2 women and 3 men, median age 27 years) with contrast-free MRI of both knees. Post-contrast T1w images and DWI images at b = 1000s/mm² with apparent diffusion coefficient (ADC) maps of patients were separately rated by two independent and blinded readers with different levels of experience for the presence or absence and degree of synovitis along with the level of confidence. We measured signal intensity on DWI of synovium, joint effusion and muscle with regions of interests and calculated the IVIM-parameters tissue diffusion coefficient (D) and perfusion fraction (f) for patients and volunteers.

RESULTS

All patients showed at least some synovial contrast enhancement, 8 (80%) children knees were diagnosed with synovitis on contrast-enhanced (= ce)-T1w, the diagnostic standard. Ratings by the first and second reader on ce-T1w and DWI showed full agreement (kappa = 1) in diagnosing synovitis and substantial agreement (k = 0,655) for the degree of synovial enhancement. Interobserver agreement on DWI showed fair agreement (k = 0,220) between both readers. Diagnostic confidence was lower on DWI. Mean D- and f-values of muscle was comparable between patients and volunteers. Effusion mean D was higher, mean f was lower, synovial mean D was lower, mean f higher in patients than in volunteers. All differences were statistically significant (p < 0.001).

CONCLUSIONS

Diffusion-weighted MRI with IVIM imaging remains a promising, though reader-dependent alternative to i.v. contrast-enhanced imaging in pediatric patients to reliably diagnose, or rule out, synovitis of the knee joint. We detected significantly restricted synovial diffusion and increased perfusion in patients compared to healthy volunteers.

TRIAL REGISTRATION

Ethical Comitee University Hospital Ulm, Nr. 320/16.

Smart and Multi-Functional Magnetic Nanoparticles for Cancer Treatment Applications: Clinical Challenges and Future Prospects

Iron oxide nanoparticle (IONPs) have become a subject of interest in various biomedical fields due to their magnetism and biocompatibility. They can be utilized as heat mediators in magnetic hyperthermia (MHT) or as contrast media in magnetic resonance imaging (MRI), and ultrasound (US). In addition, their high drug-loading capacity enabled them to be therapeutic agent transporters for malignancy treatment. Hence, smartening them allows for an intelligent controlled drug release (CDR) and targeted drug delivery (TDD). Smart magnetic nanoparticles (SMNPs) can overcome the impediments faced by classical chemo-treatment strategies, since they can be navigated and release drug via external or internal stimuli. Recently, they have been synchronized with other modalities, e.g., MRI, MHT, US, and for dual/multimodal theranostic applications in a single platform. Herein, we provide an overview of the attributes of MNPs for cancer theranostic application, fabrication procedures, surface coatings, targeting approaches, and recent advancement of SMNPs. Even though MNPs feature numerous privileges over chemotherapy agents, obstacles remain in clinical usage. This review in particular covers the clinical predicaments faced by SMNPs and future research scopes in the field of SMNPs for cancer theranostics.

Identification Markers of Carotid Vulnerable Plaques: An Update

Vulnerable plaques have been a hot topic in the field of stroke and carotid atherosclerosis. Currently, risk stratification and intervention of carotid plaques are guided by the degree of luminal stenosis. Recently, it has been recognized that the vulnerability of plaques may contribute to the risk of stroke. Some classical interventions, such as carotid endarterectomy, significantly reduce the risk of stroke in symptomatic patients with severe carotid stenosis, while for asymptomatic patients, clinically silent plaques with rupture tendency may expose them to the risk of cerebrovascular events. Early identification of vulnerable plaques contributes to lowering the risk of cerebrovascular events. Previously, the identification of vulnerable plaques was commonly based on imaging technologies at the macroscopic level. Recently, some microscopic molecules pertaining to vulnerable plaques have emerged, and could be potential biomarkers or therapeutic targets. This review aimed to update the previous summarization of vulnerable plaques and identify vulnerable plaques at the microscopic and macroscopic levels.

Contrast-enhanced MR Angiography without Gadolinium-based Contrast Material: Clinical Applications Using Ferumoxytol

Vascular imaging can be challenging because of the wide variability of contrast dynamics in different vascular territories and potential safety concerns in patients with renal insufficiency or allergies. Off-label diagnostic use of ferumoxytol, a superparamagnetic iron nanoparticle approved for therapy, is a promising alternative to gadolinium-based contrast agents for MR angiography (MRA). Ferumoxytol has exhibited a reassuring safety profile when used within the dose range recommended for diagnostic imaging. Because of its prolonged and stable intravascular residence, ferumoxytol can be used in its steady-state distribution for a wide variety of imaging indications, including some where conventional MRA is unreliable. In this article, authors discuss some of the major vascular applications of ferumoxytol and highlight how it may be used to provide highly diagnostic images and improve the quality, workflow, and reliability of vascular imaging. Keywords: MR Angiography, MRI Contrast Agent, Cardiac, Vascular © RSNA, 2022.

Do We Need Gadolinium-Based Contrast Agents for Routine MRI Surveillance of Unoperated Pituitary Macroadenoma?

BACKGROUND AND PURPOSE

The use of gadolinium-based contrast agents contributes to the cost of MR imaging and prolongs image-acquisition time. There are also recent concerns regarding gadolinium deposition, particularly in patients who require frequent follow-up MRIs. The purpose of this study was to assess whether gadolinium-based contrast agents are needed during MR imaging follow-up for unoperated pituitary macroadenoma.

MATERIALS AND METHODS

A total of 105 patients with unoperated pituitary macroadenoma who underwent follow-up MR imaging of the sella were included in this retrospective study. The craniocaudal dimension, cavernous sinus invasion grading, and optic pathway compression were assessed independently on coronal T2WI and compared with coronal T1-weighted images with gadolinium-based contrast agents (T1 postcontrast images). The agreement between the T2WI and T1 postcontrast images for the craniocaudal dimension was assessed using the intraclass correlation coefficient; for the cavernous sinus invasion and optic pathway compression, it was assessed using κ statistics.

RESULTS

There was excellent agreement for the craniocaudal dimensions between T2WI and T1 postcontrast images (intraclass correlation coefficient = 0.96, P < .001; 95% CI, 0.84-0.99). Additionally, there was almost-perfect agreement between cavernous sinus invasion and optic pathway compression between T2WI and T1 postcontrast images, with κ = 0.95 and 0.84, respectively (P < .001).

CONCLUSIONS

MR imaging of the sella without the use of gadolinium-based contrast agents could potentially be considered for the follow-up of unoperated pituitary macroadenomas. This choice can reduce the MR imaging examination cost and acquisition time and avoids potential adverse effects of gadolinium-based contrast agents.

Comparison of Contrast-Enhanced Ultrasonography to Color Doppler Ultrasound in Evaluation of Carotid Body Tumors

Objective

The objectives of this study were to prospectively 1) explore the characteristics and enhanced patterns of carotid body tumors (CBTs) at color Doppler ultrasound (CDU) and contrast-enhanced ultrasonography (CEUS) qualitatively and quantitatively and 2) compare CDU and CEUS for their morphology and vascularity signature.

Methods

CDU and CEUS with Sonovue^® were used to evaluate 25 CBT lesions. The comparison between these ultrasonic modalities included the size, Shamblin type, vascularity, and feeding vessels of the lesion areas. The time–intensity curve (TIC) analysis was used to obtain the dynamics of the contrast-enhancement features of CBTs.

Results

The TIC analysis presented a fast wash-in [wash-in time: 3.00 ± 1.10 s, mean ± SD] and slow wash-out [wash-out time: 58.79 ± 24.21 s, mean ± SD] pattern in the CBT lesions, with a high area under the curve (AUC) of 669.68 ± 143.46 mm² (mean ± SD). In comparison with CDU, CEUS was superior in identifying Shamblin type I or III CBT lesions (χ² = 17.389, p=0.002). It detected a significant difference in the AUC between moderate and marked vascularity groups (563.33 ± 102.63 vs. 707.22 ± 138.81, t=-2.311, p=0.031.), while CDU observed no significant difference between these two groups. Although CDU was more sensitive than CEUS in detecting feeding vessels (100% vs. 88%), CEUS better visualized the origins of feeding vessels (χ² = 9.162, p=0.010).

Conclusion

CEUS can better investigate the Shamblin type and vascularity of CBT lesions than CDU. CBTs displayed a fast wash-in, slow wash-out pattern with high AUC in the TIC analysis in the CEUS mode. CDU is more sensitive in detecting feeding vessels than CEUS, while CEUS can better visualize the origins of feeding vessels.

Contrast-enhanced ultrasound of the neonatal brain

Cranial US is an integral component of evaluating the neonatal brain, especially in the setting of critically ill infants and in the emergency setting, because cranial US can be performed portably at the bedside, is safe, and can be repeated whenever needed. Contrast-enhanced ultrasound (CEUS) involves intravenously injecting microbubbles to allow for improved visibility of large and small vessels to assess vascularity and is becoming a widespread technique to improve diagnostic performance of US across a broad spectrum of applications. CEUS has the potential to add value to routine brain US and become a useful adjunct to MRI in infants in need of bedside imaging. In this review we describe the basics of US contrast agents and CEUS technique, including safety considerations, and detail the potential clinical uses of brain CEUS.

Effects of chemical forms of gadolinium on the spleen in mice after single intravenous administration

Gadolinium-based contrast agents (GBCAs) are widely used to improve tissue contrast during magnetic resonance imaging. Exposure to GBCAs can result in gadolinium deposition within human tissues and has become a clinical concern because of the potential toxic effects of free gadolinium (Gd³⁺). Here, we report the impact of a single administration of GBCAs (Omniscan and Gadovist), and Gd³⁺ on mouse tissues. Five-week-old male BALB/c mice were injected intravenously with GBCAs or Gd³⁺. Seven days after injection, relatively high levels of gadolinium were detected in the spleen (118.87 nmol/g tissue), liver (83.00 nmol/g tissue), skin (48.56 nmol/g tissue), and kidneys (25.59 nmol/g tissue) of the Gd(NO₃)₃ (high dose: 0.165 mmol/kg) group; in the bones (11.12 nmol/g tissue), kidneys (7.49 nmol/g tissue), teeth (teeth: 6.18 nmol/g tissue), and skin (2.43 nmol/g tissue) of the Omniscan (high dose: 1.654 mmol/kg) group and in the kidneys (16.36 nmol/g tissue) and skin (4.88 nmol/g tissue) of the Gadovist (high dose: 3.308 mmol/kg) group. Enlargement of the spleen was observed in the Gd³⁺ group (p < 0.05), but not in the Omniscan or Gadovist groups. Gd³⁺ caused iron accumulation around the white pulp of the spleen, suggesting that enlargement of the spleen is, at least in part, associated with Gd³⁺ and/or iron accumulation. Our results may help elucidate the relative risks of different types of gadolinium agents, the mechanisms involved, and even recognition of potential toxic effects of GBCAs.

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The tissue deposition of gadolinium influenced by the chemical forms of gadolinium.

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Gd³⁺ causes enlargement and iron deposition in the spleen of mice.

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The spleen is a potential target for the release of Gd³⁺ from GBCAs.

To Contrast or Not to Contrast? On the Role of Contrast Enhancement in Hand MRI Studies of Patients with Rheumatoid Arthritis

Currently, clinical indications for the application of gadolinium-based contrast agents (GBCA) in magnetic resonance imaging (MRI) are increasingly being questioned. Consequently, this study aimed to evaluate the additional diagnostic value of contrast enhancement in MRI of the hand in patients with rheumatoid arthritis (RA). Thirty-one patients with RA (mean age, 50 ± 14 years (range, 18–72 years)) underwent morphologic MRI scans on a clinical 3 T scanner. MRI studies were analyzed based on (1) the Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) and (2) the GBCA-free RAMRIS version, termed RAMRIS Sine-Gadolinium-For-Experts (RAMRIS-SAFE), in which synovitis and tenosynovitis were assessed using the short-tau inversion-recovery sequence instead of the post-contrast T1-weighted sequence. The synovitis subscores in terms of Spearman’s ρ, as based on RAMRIS and RAMRIS-SAFE, were almost perfect (ρ = 0.937; p < 0.001), while the tenosynovitis subscores were less strongly correlated (ρ = 0.380 p = 0.035). Correlation between the total RAMRIS and RAMRIS-SAFE was also almost perfect (ρ = 0.976; p < 0.001). Inter-rater reliability in terms of Cohen’s κ was high (0.963 ≤ κ ≤ 0.925). In conclusion, RAMRIS-SAFE as the GBCA-free version of the well-established RAMRIS is a patient-friendly and resource-efficient alternative for assessing disease-related joint changes in RA. As patients with RA are subject to repetitive GBCA applications, non-contrast imaging protocols should be considered.

[Diffusion-weighted magnetic resonance imaging instead of contrast-enhanced imaging for evaluating immediate therapeutic efficacy of high-intensity focused ultrasound ablation of adenomyosis]

OBJECTIVE

To explore the feasibility of diffusion-weighted magnetic resonance imaging (DWI) instead of contrast-enhanced (CE) imaging for evaluation of the immediate therapeutic efficacy of high-intensity focused ultrasound (HIFU) ablation for treatment of adenomyosis.

METHODS

We retrospectively analyzed the data of 29 patients aged 40.5 ± 5.4 years under going HIFU treatment for adenomyosis in our hospital between December, 2017 and July, 2020. The patients received MRI examination both before and within 24 h after the operation. Two observers analyzed the morphology of the ablation area on DWI and classified the lesions into type 1 (spot-like or no obvious signal intensity changes), type 2 (patchy signal intensity changes) and type 3 (ring-like signal intensity changes). The inter- and intra-observer reliability of morphological assessment was assessed using kappa test. The volume of necrotic tissues following the ablation was measured with both DWI and CE imaging, and the consistency of the measurements and the inter- and intra-observer reliability of DWI-based measurements were evaluated using Bland-Altman plot tests.

RESULTS

The median volume of necrotic tissues was 36.9 cm3 (range 16.4-65.5 cm3) following ablation of the 29 lesions. DWI findings identified 24-25 (82.8%-86.2%) lesions with type 2 or 3 signal changes following the ablation with measurable necrotic tissue volume. On DW images, the Kappa value of intra- and inter-observer reliability for morphological classification of the ablation area reached 0.798 (P=0.000) and 0.933 (P= 0.000), respectively. Bland-Altman plots showed a good consistency of the necrotic volumes measured by CE and at DWI with a strong inter- and intra-observer reliability of DWI-based volume measurements (with only one point outside the range of 95% limits of agreement). The remaining 4 or 5 lesions, which presented with type 1 signal changes following ablation, were all small in size (the largest was only 18.61 cm3) and showed poor therapeutic responses to the ablation.

CONCLUSION

DWI-based morphological assessment and necrotic tissue volume measurement can replace CE imaging for assessment of the immediate therapeutic efficacy of HIFU ablation for treatment of adenomyosis.

What's Hot in Breast MRI

Several articles in the literature have demonstrated a promising role for breast MRI techniques that are more economic in total exam time than others when used as supplement to mammography for detection and diagnosis of breast cancer. There are many technical factors that must be considered in the shortened breast MRI protocols to cut down time of standard ones, including using optimal fat suppression, gadolinium-chelates intravascular contrast administrations for dynamic imaging with post processing subtractions and maximum intensity projections (MIP) high spatial and temporal resolution among others. Multiparametric breast MRI that includes both gadolinium-dependent, i.e., dynamic contrast-enhanced (DCE-MRI) and gadolinium-free techniques, i.e., diffusion-weighted/diffusion-tensor magnetic resonance imaging (DWI/DTI) are shown by several investigators that can provide extremely high sensitivity and specificity for detection of breast cancer. This article provides an overview of the proven indications for breast MRI including breast cancer screening for higher than average risk, determining chemotherapy induced tumor response, detecting residual tumor after incomplete surgical excision, detecting occult cancer in patients presenting with axillary node metastasis, detecting residual tumor after incomplete breast cancer surgical excision, detecting cancer when results of conventional imaging are equivocal, as well patients suspicious of having breast implant rupture. Despite having the highest sensitivity for breast cancer detection, there are pitfalls, however, secondary to false positive and false negative contrast enhancement and contrast-free MRI techniques. Awareness of the strengths and limitations of different approaches to obtain state of the art MR images of the breast will facilitate the work-up of patients with suspicious breast lesions.

Is Contrast Medium Really Needed for Follow-up MRI of Untreated Intracranial Meningiomas?

BACKGROUND AND PURPOSE

Recent concerns relating to tissue deposition of gadolinium are favoring the use of noncontrast MR imaging whenever possible. The purpose of this study was to assess the necessity of gadolinium contrast for follow-up MR imaging of untreated intracranial meningiomas.

MATERIALS AND METHODS

One-hundred twenty-two patients (35 men, 87 women) with meningiomas who underwent brain MR imaging between May 2007 and May 2019 in our institution were included in this retrospective cohort study. We analyzed 132 meningiomas: 73 non-skull base (55%) versus 59 skull base (45%), 93 symptomatic (70%) versus 39 asymptomatic (30%). Fifty-nine meningiomas underwent an operation: 54 World Health Organization grade I (92%) and 5 World Health Organization grade II (8%). All meningiomas were segmented on T1 3D-gadolinium and 2D-T2WI. Agreement between T1 3D-gadolinium and 2D-T2WI segmentations was assessed by the intraclass correlation coefficient.

RESULTS

The mean time between MR images was 1485 days (range, 760-3810 days). There was excellent agreement between T1 3D-gadolinium and T2WI segmentations (P < .001): mean tumor volume (T1 3D-gadolinium: 9012.15 [SD, 19,223.03] mm³; T2WI: 8528.45 [SD, 18,368.18 ] mm³; intraclass correlation coefficient = 0.996), surface area (intraclass correlation coefficient = 0.989), surface/volume ratio (intraclass correlation coefficient = 0.924), maximum 3D diameter (intraclass correlation coefficient = 0.986), maximum 2D diameter in the axial (intraclass correlation coefficient = 0.990), coronal (intraclass correlation coefficient = 0.982), and sagittal planes (intraclass correlation coefficient = 0.985), major axis length (intraclass correlation coefficient = 0.989), minor axis length (intraclass correlation coefficient = 0.992), and least axis length (intraclass correlation coefficient = 0.988). Tumor growth also showed good agreement (P < .001), estimated as a mean of 461.87 [SD, 2704.1] mm³/year on T1 3D-gadolinium and 556.64 [SD, 2624.02 ] mm³/year on T2WI.

CONCLUSIONS

Our results show excellent agreement between the size and growth of meningiomas derived from T1 3D-gadolinium and 2D-T2WI, suggesting that the use of noncontrast MR imaging may be appropriate for the follow-up of untreated meningiomas, which would be cost-effective and avert risks associated with contrast media.

Contrast-Enhanced Ultrasound in Children: Implementation and Key Diagnostic Applications

Contrast-enhanced ultrasound (CEUS) utilization is expanding rapidly, particularly in children, in whom the modality offers important advantages of dynamic evaluation of the vasculature, portability, lack of ionizing radiation, and lack of need for sedation. Accumulating data establish an excellent safety profile of ultrasound contrast agents in children. Although only FDA-approved for IV use in children for characterizing focal liver lesions and for use during echocardiography, growing off-label applications are expanding the diagnostic potential of ultrasound. Focal liver lesion evaluation is the most common use of CEUS, and the American College of Radiology Pediatric LI-RADS Working Group recommends including CEUS for evaluation of a newly discovered focal liver lesion in many circumstances. Data also support the role of CEUS in hemodynamically stable children with blunt abdominal trauma, and CEUS is becoming a potential alternative to CT in this setting. Additional potential applications that require further study include evaluation of pathology in the lung, spleen, brain, pancreas, bowel, kidney, female pelvis, and scrotum. This review explores the implementation of CEUS in children, describing basic principles of ultrasound contrast agents and CEUS technique and summarizing current and potential IV diagnostic applications based on pediatric-specific supporting evidence.

Manganese(II)-Based Responsive Contrast Agent Detects Glucose-Stimulated Zinc Secretion from the Mouse Pancreas and Prostate by MRI

A Mn(II)-based zinc-sensitive MRI contrast agent, MnPyC3A-BPEN, was prepared, characterized, and applied in imaging experiments to detect glucose-stimulated zinc secretion (GSZS) from the mouse pancreas and prostate in vivo. Thermodynamic and kinetic stability tests showed that MnPyC3A-BPEN has superior kinetic inertness compared to GdDTPA, is less susceptible to transmetalation in the presence of excess Zn2+ ions, and less susceptible to transchelation by albumin. In comparison with other gadolinium-based zinc sensors bearing a single zinc binding moiety, MnPyC3A-BPEN appears to be a reliable alternative for imaging β-cell function in the pancreas and glucose-stimulated zinc secretion from the prostate.

Theranostic Nanomedicine for Synergistic Chemodynamic Therapy and Chemotherapy of Orthotopic Glioma

Glioma is a common primary brain malignancy with a poor prognosis. Chemotherapy is the first-line treatment for brain tumors but low efficiency of drugs in crossing the blood-brain barrier (BBB) and drug resistance related to tumor hypoxia thwart its efficacy. Herein, a theranostic nanodrug (iRPPA@TMZ/MnO) is developed by incorporating oleic acid-modified manganese oxide (MnO) and temozolomide (TMZ) into a polyethylene glycol-poly(2-(diisopropylamino)ethyl methacrylate-based polymeric micelle containing internalizing arginine-glycine-aspartic acid (iRGD). The presence of iRGD provides the nanodrug with a high capacity of crossing the BBB and penetrating the tumor tissue. After accumulation in glioma, the nanodrug responds to the tumor microenvironment to simultaneously release TMZ, Mn2+, and O2. The released TMZ induces tumor cell apoptosis and the released Mn2+ causes intracellular oxidative stress that kill tumor cells via a Fenton-like reaction. The O2 produced in situ alleviates tumor hypoxia and enhances the chemotherapy/chemodynamic therapeutic effects against glioma. The Mn2+ can also serve as a magnetic resonance imaging (MRI) contrast agent for tumor imaging during therapy. The study demonstrates the great potential of this multifunctional nanodrug for MRI-visible therapy of brain glioma.

Early Transmural Response Assessed Using Magnetic Resonance Imaging Could Predict Sustained Clinical Remission and Prevent Bowel Damage in Patients with Crohn's Disease Treated with Anti-Tumour Necrosis Factor Therapy

BACKGROUND

Magnetic resonance imaging [MRI] is a promising tool to evaluate therapeutic efficacy in ileocolonic Crohn's disease [CD].

AIMS

We aimed to assess the feasibility of early MRI evaluation (week 12 [W12]) to predict corticosteroid-free remission [CFREM] at W52 and prevent long-term bowel damage.

METHODS

All patients with active CD needing anti-tumour necrosis factor [anti-TNF] therapy were consecutively enrolled in this multicentre prospective study. MRI was performed before starting therapy, at W12 and W52. CFREM was defined as Crohn's Disease Activity Index < 150, C-reactive protein < 5 mg/L and faecal calprotectin < 250 µg/g, with no switch of anti-TNF agents, no bowel resection and no therapeutic intensification between W12 and W52.

RESULTS

Among 46 patients, 22 [47.8%] achieved CFREM at W52. Anti-TNF agents were able to heal almost all CD lesions as soon as W12 [p < 0.05]. Early transmural response defined as a 25% decrease of either Clermont score (odds ratio [OR] = 7.7 [1.7-34.0], p < 0.001) or Magnetic Resonance Index of Activity (OR = 4.2 [1.3-13.3], p = 0.015) was predictive of CFREM at W52. Achieving at least two items on W12-MRI among ulceration healing, disappearance of enlarged lymph nodes or sclerolipomatosis, ΔADC [apparent diffusion coefficient] > +10% or ΔRCE [relative contrast enhancement] > -30% was associated with a likelihood of CFREM at W52 of 84.6% vs 37.5% in patients without transmural response [p < 0.001]. Early transmural response could prevent bowel damage progression over time using Clermont score (hazard ratio = 0.21 [0.0-0.9]; p = 0.037).

CONCLUSION

Evaluation of early transmural response by MRI is feasible and is a promising end point to monitor therapeutic efficacy in patients with CD.

Effect of at Least 10 Serial Gadobutrol Administrations on Brain Signal Intensity Ratios on T1-Weighted MRI in Children: A Matched Case-Control Study

BACKGROUND. An association is recognized between linear gadolinium-based contrast agents (GBCAs) and intracranial gadolinium retention in children. The relation between macrocyclic GBCAs and gadolinium retention remains incompletely understood. OBJECTIVE. The purpose of this study was to assess whether 10 or more administrations of the macrocyclic GBCA gadobutrol are associated with increased signal intensity (SI) in the dentate nucleus (DN) and globus pallidus (GP) on unenhanced T1-weighted MRI of children and to explore clinical variables potentially associated with T1 hyperintensity. METHODS. The case group consisted of 25 children (13 boys, 12 girls; mean age, 7 ± 4 years; range, 2-18 years) who underwent at least 10 (mean, 15 ± 6; range, 10-34) contrast-enhanced MRI examinations exclusively with gadobutrol. The control group consisted of 25 age- and sex-matched patients undergoing MRI who had never been exposed to gadolinium. Two observers in consensus using a 3-point scale assessed visual T1 hyperintensity in the DN and GP. One observer placed ROIs on T1-weighted images to mark the DN, GP, middle cerebellar peduncle (MCP), and pulvinar of the thalamus bilaterally to compute mean DN-to-MCP and GP-to-thalamus SI ratios. SI ratios were compared between the macrocyclic GBCA and control groups. In the macrocyclic GBCA group, Pearson correlation analysis was conducted between SI ratios and clinical variables. ROI measurements were repeated by the original reader and an independent reader, and interobserver and intraobserver agreement were computed by means of Lin concordance correlation coefficient (ρ_c). RESULTS. No patient had visual T1 hyperintensity in the DN or GP. No significant difference between the macrocyclic GBCA and control groups was observed for DN-to-MCP SI ratio (0.95 ± 0.05 vs 0.95 ± 0.03; p = .67) or GP-to-thalamus SI ratio (1.05 ± 0.06 vs 1.04 ± 0.06; p = .65). In the macrocyclic GBCA group, no significant correlation was observed between DN-to-MCP SI ratio or GP-to-thalamus SI ratio and age (r = 0.355, p = .08; r = 0.167, p = .42), number of contrast-enhanced MRI examinations (r = 0.247, p = .23; r = 0.203, p = .33), mean time between examinations (r = 0.193, p = .36; r = 0.047, p = .82), or cumulative macrocyclic GBCA dose (r = 0.434, p = .07; r = 0.270, p = .19). Interobserver and intraobserver agreement was substantial for DN-to-MCP SI and GP-to-TH SI ratios (ρ_c = 0.931-0.974). CONCLUSION. Ten or more serial gadobutrol administrations were not associated with T1 hyperintensity in the DN or GP of children. CLINICAL IMPACT. Selection of gadobutrol as an MRI contrast agent may reduce risk of gadolinium retention in children. The findings may help guide practices for GBCA administration to children.

VOLT: a novel open-source pipeline for automatic segmentation of endolymphatic space in inner ear MRI

Background

Objective and volumetric quantification is a necessary step in the assessment and comparison of endolymphatic hydrops (ELH) results. Here, we introduce a novel tool for automatic volumetric segmentation of the endolymphatic space (ELS) for ELH detection in delayed intravenous gadolinium-enhanced magnetic resonance imaging of inner ear (iMRI) data.

Methods

The core component is a novel algorithm based on Volumetric Local Thresholding (VOLT). The study included three different data sets: a real-world data set (D1) to develop the novel ELH detection algorithm and two validating data sets, one artificial (D2) and one entirely unseen prospective real-world data set (D3). D1 included 210 inner ears of 105 patients (50 male; mean age 50.4 ± 17.1 years), and D3 included 20 inner ears of 10 patients (5 male; mean age 46.8 ± 14.4 years) with episodic vertigo attacks of different etiology. D1 and D3 did not differ significantly concerning age, gender, the grade of ELH, or data quality. As an artificial data set, D2 provided a known ground truth and consisted of an 8-bit cuboid volume using the same voxel-size and grid as real-world data with different sized cylindrical and cuboid-shaped cutouts (signal) whose grayscale values matched the real-world data set D1 (mean 68.7 ± 7.8; range 48.9–92.8). The evaluation included segmentation accuracy using the Sørensen-Dice overlap coefficient and segmentation precision by comparing the volume of the ELS.

Results

VOLT resulted in a high level of performance and accuracy in comparison with the respective gold standard. In the case of the artificial data set, VOLT outperformed the gold standard in higher noise levels. Data processing steps are fully automated and run without further user input in less than 60 s. ELS volume measured by automatic segmentation correlated significantly with the clinical grading of the ELS (p < 0.01).

Conclusion

VOLT enables an open-source reproducible, reliable, and automatic volumetric quantification of the inner ears’ fluid space using MR volumetric assessment of endolymphatic hydrops. This tool constitutes an important step towards comparable and systematic big data analyses of the ELS in patients with the frequent syndrome of episodic vertigo attacks. A generic version of our three-dimensional thresholding algorithm has been made available to the scientific community via GitHub as an ImageJ-plugin.

Comparison of Clinical Examination and Various Imaging Modalities in the Diagnosis of Head and Neck Cancer

Introduction  Squamous cell Carcinoma of the Head and Neck (HNSCC) is the most common tumor entity of malignant processes in the head and neck area. Due to the metastasizing behavior of these tumors, the staging is indispensable for the treatment planning and requires imaging techniques, which are sensitive, specific, and as far as possible cost-effective, to benefit ultimately the patient and to ensure optimal care. Objectives  The aim of the present study is to compare the clinical examination including palpation, ultrasound and computed tomography (CT)/magnetic resonance imaging (MRI) for the diagnosis of neck metastases to make the correct indication for a neck dissection. Methods  Data from 286 patients with HNSCC were analyzed for neck metastases to determine which diagnostic tool is the best to answer the question if a neck dissection is necessary or not. Each study method was examined retrospectively by comparing sensitivity, specificity, the positive/negative predictive value, the positive likelihood ratio and the diagnostic accuracy. Results  The ultrasound showed a sensitivity of 91.52%, a specificity of 61.67%, a positive/negative predictive value of 76.65%/84.09%, a positive likelihood ratio of 2.39 and a diagnostic accuracy of 78.95%. The clinical examination showed a sensitivity of 75.76%, a specificity of 66.12%, a positive/negative predictive value of 75.30%/66.67%, a positive likelihood ratio of 2.24 and a diagnostic accuracy of 71.68%. The CT/MRI showed a sensitivity of 78.66%, a specificity of 62.50%, a positive/negative predictive value of 74.14%/68.18%, a positive likelihood ratio of 2.10 and a diagnostic accuracy of 71.83%. Radiographically, ultrasound, as well as the clinical examination, could be judged to be free from radiation load and side effects from the contrast medium. The high dependence on the investigator when using ultrasound made reproducibility of the results difficult. Conclusions  It could be shown that ultrasound was the diagnostic tool with the highest sensitivity, positive/negative predictive value, positive likelihood ratio and diagnostic accuracy by detecting and interpreting metastases in the head and neck region correctly. Whether a neck dissection should be performed depends to a large extent on the ultrasound findings.

Team Approach: Pediatric Musculoskeletal Infection

A team approach is optimal in the evaluation and treatment of musculoskeletal infection in pediatric patients given the complexity and uncertainty with which such infections manifest and progress, particularly among severely ill children. The team approach includes emergency medicine, pediatric intensive care, pediatric hospitalist medicine, infectious disease service, orthopaedic surgery, radiology, anesthesiology, pharmacology, and hematology. These services follow evidence-based clinical practice guidelines with integrated processes of care so that children and their families may benefit from data-driven continuous process improvement. Important principles based on our experience in the successful treatment of pediatric musculoskeletal infection include relevant information gathering, pattern recognition, determination of the severity of illness, institutional workflow management, closed-loop communication, patient and family-centered care, ongoing dialogue among key stakeholders within and outside the context of direct patient care, and periodic data review for programmatic improvement over time. Such principles may be useful in almost any setting, including rural communities and developing countries, with the understanding that the team composition, institutional capabilities or limitations, and specific approaches to treatment may differ substantially from one setting or team to another.

Diagnostic value of diffusion-weighted MRI for imaging synovitis in pediatric patients with inflammatory conditions of the knee joint

BACKGROUND

Diffusion-weighted imaging (DWI) of synovitis has been suggested as a possible non-invasive alternative to contrast-enhanced T1w imaging (ce-T1w). We aimed to study DWI for diagnosing synovitis in the knee joint of pediatric patients, to quantify inter-observer agreement on DWI and ce-T1w and to calculate quantitative measures of synovial diffusivity and conspicuity.

METHODS

Forty consecutive patients with known or suspected arthritis of the knee (25 girls, median age 12 years) underwent routine 1.5T MRI with ce-T1w and transverse DWI with b values 50 and 800 s/mm². Mean apparent diffusion coefficient (ADC) values and signal intensity of inflamed synovium, joint effusion and muscle were measured with regions of interest retrospectively. Post-contrast T1w images (diagnostic standard) and diffusion-weighted images at b = 800 s/mm² with ADC map were separately rated by three independent and blinded readers with different levels of expertise for the presence and degree of synovitis along with the level of diagnostic confidence.

RESULTS

Thirty-one (78%) patients showed at least some synovial contrast enhancement, 17 (43%) children were diagnosed with synovitis on ce-T1w. Ratings by the 1st reader on ce-T1w and on DWI for synovitis showed very good agreement (kappa = 0.90). Inter-observer agreement on DWI ranged from moderate to substantial with kappa values between 0.68 and 0.79 (all P < 0.001). Agreement and diagnostic confidence were generally lower in patients with mild and without synovial enhancement, compared to patients with synovitis. DWI yielded higher signal of inflamed synovium vs. muscle tissue, but lower signal vs. joint effusion, compared to ce-T1w (all P < 0.001).

CONCLUSIONS

Diffusion-weighted imaging is a promising, though reader-dependent alternative to contrast-enhanced imaging in patients with arthritis of the knee, based on our preliminary findings. It holds potential for increasing patient safety and comfort.

Evaluation of 3.0-T MRI Brain Signal after Exposure to Gadoterate Meglumine in Women with High Breast Cancer Risk and Screening Breast MRI

Background Otherwise healthy women at high risk for breast cancer undergo annual contrast agent-enhanced breast MRI screening examinations, resulting in high cumulative doses of gadolinium-based contrast agents (GBCAs). Whereas the majority of studies showed no T1 signal ratio increase in deep brain nuclei after more than six doses of macrocyclic GBCA, this has not been explored in a healthy study population. Purpose To assess whether women who are administered large cumulative doses of macrocyclic GBCA with breast MRI at high-risk breast cancer screening exhibit T1 alterations in deep brain nuclei. Materials and Methods In this prospective study from November 2017 to March 2018, healthy women who were either exposed (because of high-risk breast cancer screening) or unexposed to only gadoterate meglumine underwent 3.0-T brain MRI with a dedicated head coil, including T1 mapping and magnetization-prepared rapid gradient-echo sequences. T1 times and T1 signal intensities were measured in the dentate nucleus (DN), globus pallidus (GP), crus anterior of capsula interna (CA), and pons. Ratios of DN to pons and GP to CA were calculated, and univariable Pearson correlation coefficients were calculated. Multivariable analysis included partial regression analysis. Results This study evaluated 25 women (mean age, 51 years ± 11 [standard deviation]) who were exposed to a mean GBCA dose of 129 mL (median 112 mL; range, 70-302 mL) and 16 women (mean age, 37 years ± 10) who were never exposed to any GBCA. Infratentorially, no correlation between cumulative GBCA dose and T1 times or signal intensity ratios was detected (P = .66 and .55, respectively). In partial correlation analysis by considering age as a confounder, there was a moderate negative correlation between GP-to-CA ratio and GBCA dose (r = -0.40; P = .01) but not for GP T1 times (r = 0.19; P = .24). Conclusion After administration of relatively large cumulative doses of gadoterate dimeglumine, healthy women at high risk for breast cancer who underwent annual contrast-enhanced breast MRI screening did not exhibit T1 signal increase in deep brain nuclei at 3.0-T MRI. © RSNA, 2019.

Quality Improvement of Magnetic Resonance Imaging for Musculoskeletal Infection in Children Results in Decreased Scan Duration and Decreased Contrast Use

BACKGROUND

Magnetic resonance imaging (MRI) is a heavily utilized resource to evaluate children suspected to have a musculoskeletal infection. Complex interdisciplinary workflows are involved with decision-making with regard to indications, anesthesia, contrast use, and procedural timing relative to the scan. This study assesses the impact of a quality improvement endeavor on MRI workflows at a tertiary pediatric medical center.

METHODS

A registry of consecutively enrolled children for a multidisciplinary musculoskeletal infection program identified those evaluated with MRI from 2012 to 2018. Annual MRI process improvement feedback was provided to the key stakeholders. Demographic characteristics, laboratory parameters, MRI indications, anesthesia use, MRI findings, final diagnoses, scan duration, imaging protocol, surgical intervention following MRI, and length of stay were retrospectively compared between the 3 cohorts (initial, middle, and final) representing 2-year increments to assess the impact of the initiative.

RESULTS

There were 526 original MRI scans performed to evaluate 1,845 children with suspected musculoskeletal infection. Anesthesia was used in 401 children (76.2%). When comparing the initial, middle, and final study period cohorts, significant improvement was demonstrated for the number of sequences per scan (7.5 sequences for the initial cohort, 5.8 sequences for the middle cohort, and 4.6 sequences for the final cohort; p < 0.00001), scan duration (73.6 minutes for the initial cohort, 52.1 minutes for the middle cohort, and 34.9 minutes for the final cohort; p < 0.00001), anesthesia duration (94.1 minutes for the initial cohort, 68.9 minutes for the middle cohort, and 53.2 minutes for the final cohort; p < 0.00001), and the rate of contrast use (87.6% for the initial cohort, 67.7% for the middle cohort, and 26.3% for the final cohort; p < 0.00001). There was also a trend toward a higher rate of procedures under continued anesthesia immediately following the MRI (70.2% in the initial cohort, 77.8% in the middle cohort, and 84.6% in the final cohort). During the final 6-month period, the mean scan duration was 24.4 minutes, anesthesia duration was 40.9 minutes, and the rate of contrast administration was 8.5%.

CONCLUSIONS

Progressive quality improvement through collaborative interdisciplinary communication and workflow redesign led to improved utilization of MRI and minimized contrast use for suspected musculoskeletal infection. There was a high rate of procedural intervention under continued anesthesia for children with confirmed musculoskeletal infection.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Role of Iterative Reconstruction Algorithm for the Assessment of Myocardial Infarction with Dual Energy Computed Tomography

RATIONALE AND OBJECTIVES

Low monochromatic energy levels (40 keV) derived from delayed enhancement dual energy cardiac computed tomography (DE-DECT) allow the evaluation of myocardial infarcts (MI) among stable patients, although at the expense of high image noise. We explored whether the application of adaptive statistical iterative reconstruction (ASIR) to 40-keV DE-DECT (unavailable with previous software versions) might improve image quality and detection of MI in stable patients.

MATERIALS AND METHODS

We prospectively enrolled patients with a history of previous MI, and performed delayed-enhancement cardiac magnetic resonance (DE-CMR) and DE-DECT within the same week. DE-DECT images were reconstructed with 0% and 60% ASIR.

RESULTS

MI was identified in 18 (80%) patients with both DE-CMR and DE-DECT. On a per segment basis, we did not identify significant differences regarding the diagnostic performance of DE-DECT with and without ASIR [area under receiver operating characteristic curve 0.86 vs. 0.83, p = 0.10]. The application of ASIR improved the signal-to-noise ratio of DE-DECT with 0% ASIR compared to DE-DECT with 60% ASIR (6.07 ± 2.1 vs. 11.1 ± 4.5, p < 0.0001). However, qualitative assessment of MI image quality (3.35 ± 1.2, vs. 3.55 ± 1.1, p = 0.10) and diagnostic confidence (4.40 ± 0.9 vs. 4.60 ± 0.8, p = 0.10) were not significantly improved. Using DE-DECT with 60% ASIR, a threshold over 199 HU showed a sensitivity of 67% and a specificity of 92% for the detection of segments with MI.

CONCLUSION

In this study, DE-DECT allowed accurate detection of MI among stable patients compared with DE-CMR, and the application of ASIR improved signal-to-noise ratio of DE-DECT, although the diagnostic performance showed only non-significant improvements.

A probabilistic atlas of the human inner ear's bony labyrinth enables reliable atlas-based segmentation of the total fluid space

Intravenous contrast agent-enhanced magnetic resonance imaging of the endolymphatic space (ELS) of the inner ear permits direct, in-vivo, non-invasive visualization of labyrinthine structures and thus verification of endolymphatic hydrops (ELH). However, current volumetric assessment approaches lack normalization. The aim of this study was to develop a probabilistic atlas of the inner ear's bony labyrinth as a first step towards an automated and reproducible volume-based quantification of the ELS. The study included three different datasets: a source dataset (D1) to build the probabilistic atlas and two testing sets (D2, D3). D1 included 24 right-handed patients (12 females; mean age 51.5 ± 3.9 years) and D2 5 patients (3 female; mean age 48.8 ± 5.01 years) with vestibular migraine without ELH or any measurable vestibular deficits. D3 consisted of five patients (one female; mean age 46 ± 5.2 years) suffering from unilateral Menière's disease and ELH. Data processing comprised three steps: preprocessing using an affine and deformable fusion registration pipeline, computation of an atlas for the left and right inner ear using a label-assisted approach, and validation of the atlas based on localizing and segmenting previously unseen ears. The three-dimensional probabilistic atlas of the inner ear's bony labyrinth consisted of the internal acoustic meatus and inner ears (including cochlea, otoliths, and semicircular canals) for both sides separately. The analyses showed a high level of agreement between the atlas-based segmentation and the manual gold standard with an overlap of 89% for the right ear and 86% for the left ear (measured by dice scores). This probabilistic in vivo atlas of the human inner ear's bony labyrinth and thus of the inner ear's total fluid space for both ears represents a necessary step towards a normalized, easily reproducible and reliable volumetric quantification of the perilymphatic and endolymphatic space in view of MR volumetric assessment of ELH. The proposed atlas lays the groundwork for state-of-the-art approaches (e.g., deep learning) and will be provided to the scientific community.

Noncontrast vestibular schwannoma surveillance imaging including an MR cisternographic sequence: is there a need for postcontrast imaging?

OBJECTIVE

The purpose of this study was to evaluate the use of a noncontrast MRI protocol that includes a cisternographic sequence (CISS/FIESTA/3D DRIVE) compared to a protocol that includes a gadolinium-enhanced sequence in order to determine whether a noncontrast approach could be utilized to follow vestibular schwannomas.

METHODS

A total of 251 patients with vestibular schwannomas who underwent MRI of the temporal bones that included both cisternographic sequence and postcontrast T1 imaging between January 2000 and January 2016 for surveillance were included in this retrospective study. The size of the vestibular schwannomas was independently assessed on a noncontrast MR cisternographic sequence and compared to size measurements on a postcontrast sequence. The evaluation of intralesional cystic components (identified as T2 signal hyperintensity) and hemorrhagic components (identified with intrinsic T1 hyperintensity) on noncontrast MR sequences was compared to evaluation on postcontrast MR sequences to determine whether additional information could be derived from the postcontrast sequences. Additionally, any potentially clinically significant, incidentally detected findings on the postcontrast T1 sequences were documented and compared with the detection of these findings on the precontrast images.

RESULTS

No significant difference in vestibular schwannoma size was found when comparing measurements made on the images obtained with the MR cisternographic sequence and those made on images obtained with the postcontrast sequence (p = 0.99). Noncontrast MR images were better (detection rate of 87%) than postcontrast images for detection of cystic components. Noncontrast MR images were also better for identifying hemorrhagic components. No additional clinically relevant information regarding the tumors was identified on the postcontrast sequences.

CONCLUSIONS

Based on the results of this study, a noncontrast MR protocol that includes a cisternographic sequence would be sufficient for the accurate characterization of size and signal characteristics of vestibular schwannomas, obviating the need for gadolinium contrast administration for the routine surveillance of these lesions.

Deep Learning for Diagnosis of Chronic Myocardial Infarction on Nonenhanced Cardiac Cine MRI

Background Renal impairment is common in patients with coronary artery disease and, if severe, late gadolinium enhancement (LGE) imaging for myocardial infarction (MI) evaluation cannot be performed. Purpose To develop a fully automatic framework for chronic MI delineation via deep learning on non-contrast material-enhanced cardiac cine MRI. Materials and Methods In this retrospective single-center study, a deep learning model was developed to extract motion features from the left ventricle and delineate MI regions on nonenhanced cardiac cine MRI collected between October 2015 and March 2017. Patients with chronic MI, as well as healthy control patients, had both nonenhanced cardiac cine (25 phases per cardiac cycle) and LGE MRI examinations. Eighty percent of MRI examinations were used for the training data set and 20% for the independent testing data set. Chronic MI regions on LGE MRI were defined as ground truth. Diagnostic performance was assessed by analysis of the area under the receiver operating characteristic curve (AUC). MI area and MI area percentage from nonenhanced cardiac cine and LGE MRI were compared by using the Pearson correlation, paired t test, and Bland-Altman analysis. Results Study participants included 212 patients with chronic MI (men, 171; age, 57.2 years ± 12.5) and 87 healthy control patients (men, 42; age, 43.3 years ± 15.5). Using the full cardiac cine MRI, the per-segment sensitivity and specificity for detecting chronic MI in the independent test set was 89.8% and 99.1%, respectively, with an AUC of 0.94. There were no differences between nonenhanced cardiac cine and LGE MRI analyses in number of MI segments (114 vs 127, respectively; P = .38), per-patient MI area (6.2 cm² ± 2.8 vs 5.5 cm² ± 2.3, respectively; P = .27; correlation coefficient, r = 0.88), and MI area percentage (21.5% ± 17.3 vs 18.5% ± 15.4; P = .17; correlation coefficient, r = 0.89). Conclusion The proposed deep learning framework on nonenhanced cardiac cine MRI enables the confirmation (presence), detection (position), and delineation (transmurality and size) of chronic myocardial infarction. However, future larger-scale multicenter studies are required for a full validation. Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Leiner in this issue.

Detection of recurrent brain tumors in children: No significant difference in sensitivity between unenhanced and contrast-enhanced MRI

BACKGROUND

Magnetic resonance imaging (MRI) with a gadolinium injection is currently used in the follow-up of children in remission of cerebral tumors (CTs). Intracerebral gadolinium deposition has been recently reported with unknown risks. The aim of this study was to evaluate the sensitivity of unenhanced brain MRI (U-MRI) in detection of tumor recurrence.

METHODS AND MATERIALS

A set of 58 U-MRIs of children in remission was retrospectively evaluated by three seniors (a neuroradiologist, a pediatric and a general radiologist) and one junior to look for any recurrence. Clinical, tumoral and imaging data were collected. The final diagnosis was anatomopathological when available, or the clinicoradiological evolution. Sensitivity, specificity, predictive values and interobserver agreement were calculated. A Fisher test and Fleiss kappa coefficient were performed.

RESULTS

For the seniors, the U-MRI had a sensitivity of 81% (95% confidence interval (CI): 0.56-0.90), and a negative predictive value (NPV) of 82% (95% CI: 0.63-0.94). The U-MRI sensitivity, regardless of the observer, was not significantly different from the contrast-enhanced MRI sensitivity (86%) according to a Fisher test (p > 0.05). No significant difference in sensitivity within the subgroups was found. The interobserver agreement of seniors was good (κ = 0.68).

CONCLUSION

U-MRI brain was suboptimal for 80% of patients. Three-dimensional millimetric, fluid-attenuated inversion recovery, and diffusion would constitute helpful sequences in follow-up. Further specific studies depending on each tumor type are still required to determine whether a potential abstention of gadolinium intravenous injection should be discussed for children.

Bowel wall healing assessed using magnetic resonance imaging predicts sustained clinical remission and decreased risk of surgery in Crohn's disease

BACKGROUND

Endoscopic mucosal healing is considered as the best therapeutic target in Crohn's disease (CD) as it is associated with better long-term outcomes. We investigated whether bowel wall healing (BWH) assessed using magnetic resonance imaging (MRI) could predict favorable outcomes and could be a potential therapeutic target.

METHODS

We performed a post hoc analysis from two prospective studies (n = 174 patients). All the patients with previous objective signs of bowel inflammation and assessed by MRI for therapeutic efficacy had a standardized and blinded evaluation, and underwent MRI. Complete BWH was defined as no segmental MaRIA > 7 or no segmental Clermont score > 8.4 and BWH as no segmental MaRIA > 11 or no segmental Clermont score > 12.5. Clinical corticosteroid-free remission (CFREM) was defined as no reappearance or worsening of clinical manifestation leading to therapeutic modification, hospitalization or CD-related surgery. Multivariate analyses were performed including all the relevant parameters.

RESULTS

Overall, 63 patients with CD were included (mean follow-up = 4.8 ± 3.1 semesters). In multivariate analysis (n = 303 semesters), complete BWH or BWH was associated with sustained CFREM according to MaRIA [OR = 4.42 (2.29-26.54); p = 0.042 and OR = 3.43 (1.02-27.02); p = 0.047, respectively] or Clermont score [OR = 3.09 (1.01-12.91); p = 0.049 and OR = 3.88 (1.40-13.80); p = 0.036, respectively]. In multivariate analysis (n = 63 patients), complete BWH or BWH was associated with decreased risk of surgery using MaRIA [HR = 0.16 (0.043-0.63); p = 0.008 and HR = 0.24 (0.07-0.77); p = 0.017, respectively] or Clermont score [HR = 0.24 (0.07-0.78); p = 0.016 and HR = 0.23 (0.07-0.76); p = 0.016, respectively].

CONCLUSIONS

MRI endpoints are predictive of favorable outcomes after medical therapy and could be used as therapeutic target in daily practice and clinical trials.

Physicians' awareness of gadolinium retention and MRI timing practices in the longitudinal management of pituitary tumors: a "Pituitary Society" survey

PURPOSE

In view of mounting attention related to possible brain retention of gadolinium-based contrast agents (GBCAs) in patients with normal renal function, our purpose was to detail results from a survey of pituitary experts to assess: 1) the timing interval and frequency of pituitary magnetic resonance imaging (MRI) following surgical and/or medical and/or radiation therapy of pituitary tumors, 2) awareness of the types of GBCAs used and their possible safety issues.

METHODS

The Pituitary Society Education Committee composed a survey with 12 multiple choice questions, 8 of which specifically addressed the time interval and frequency of MRI in the longitudinal management of pituitary tumors. The survey was distributed at two meetings; the International Pituitary Neurosurgeons Society conference in San Diego, CA, on February 18th, 2018, and the Pituitary Society Membership and Career Development Forum, Chicago, IL on March 18th, 2018.

RESULTS

There is consensus among pituitary endocrinologists and neurosurgeons that long-term repeated imaging is recommended in most pituitary tumors, although the precise strategy of timing varied depending on the specialist group and the specific clinical context of the adenoma. The data also suggest that International Pituitary Neurosurgeons Society neurosurgeons, as well as Pituitary Society neuroendocrinologists, are sometimes unaware of which contrast agents are used by their institution, and many are also unaware that evidence of long-term brain retention has been reported with the use of GBCAs in patients with normal function.

CONCLUSIONS

International pituitary endocrinologists and pituitary neurosurgeons experts suggest ongoing MRIs for the management of pituitary tumors; strategies vary based on clinical context, but also on individual experience and practice.

Quantitative DWI predicts event-free survival in children with neuroblastic tumours: preliminary findings from a retrospective cohort study

Background

Quantitative diffusion-weighted imaging (DWI) probes into tissue microstructure in solid tumours. In this retrospective ethically approved study, we investigated DWI as a potential non-invasive predictor of tumour dignity and prognosis in paediatric patients with neuroblastic tumours.

Methods

Nineteen consecutive patients with neuroblastoma (NB, n = 15), ganglioneuroblastoma (GNB, n = 1) and ganglioneuroma (GN, n = 3) underwent 3-T magnetic resonance imaging at first diagnosis and after 3-month follow-up, following a protocol including DWI (b = 50 and 800 s/mm²) in addition to standard sequences. All DWI scans were analysed for tumour volume assessment and apparent diffusion coefficient (ADC) calculation. Correlation with tumour pathology and risk factors (bone-marrow metastases, MYCN-amplification and 1p-deletion), therapeutic regime (observation versus chemotherapy) and clinical follow-up was evaluated.

Results

At baseline, mean ADC in NB was lower than in GNB/GN (0.76 vs. 1.47 × 10⁻³ mm²/s, p = 0.003). An ADC cutoff ≤ 1.05 identified malignant disease with 100.0% sensitivity (95% confidence interval [CI] 29.2–100.0%) and 93.8% specificity (95% CI 69.8–99.8%). Initial ADC was < 0.80 in all NB patients with eventual tumour relapse. During follow-up, tumour ADC values increased in the observation group (NB/GN) without relapse (p = 0.043). In eventually relapsing tumours, ADC values at follow-up tended to decrease further despite reduction in tumour volume.

Conclusions

ADC values at first presentation differed significantly between malignant and benign neuroblastic tumours. Low baseline ADC was predictive of tumour progression and relapse in NB patients. With therapy, increasing ADC values appeared to predict relapse-free survival, while a decreasing ADC during therapy was an indicator of poor prognosis.

Diagnostic usefulness of arterial spin labeling in MR negative children with new onset seizures

PURPOSE

Arterial spine labeling (ASL) magnetic resonance imaging (MRI) is the non-invasive measurement of cerebral blood flow that can localize the seizure focus in patients with epilepsy. The aim of this study was to identify its utility for localizing the seizure focus in children with no structural lesion on MRI.

METHODS

Forty-three consecutive children who underwent electroencephalography (EEG) and structural MRI, along with ASL for evaluation of newly developed seizures, were included. ASL abnormalities were classified as hypo/hyperperfusion, based on visual assessment, and compared with the seizure focus determined by clinical information and EEG.

RESULTS

Among the 43 patients (M 17: F 26, mean age, 6.3 ± 3.3 years), the seizure type was focal in 36 patients and generalized in seven patients. Twenty-five (58.1%) patients showed perfusion change. Out of 36 patients with focal seizure, 24 (66.7%) showed ASL abnormalities, and 19 (52.8%) showed concordance between ASL and clinical focus. Out of seven patients with generalized seizure, only one patient showed ASL abnormalities. The overall concordance revealed moderate agreement (k = 0.542). ASL acquisition within one day from seizure onset was the only significant associating factor with the concordance between the two (p =  0. 014).

CONCLUSION

To our knowledge, this is the first study to assess the usefulness of ASL MRI to assist in localizing the seizure focus in MR-negative children with new onset seizures. The combined use of ASL with EEG and structural MRI may play an important role in the evaluation of pediatric epilepsy.

Standardizing Magnetic Resonance Imaging Protocols, Requisitions, and Reports in Multiple Sclerosis: An Update for Radiologist Based on 2017 Magnetic Resonance Imaging in Multiple Sclerosis and 2018 Consortium of Multiple Sclerosis Centers Consensus Guidelines

The advent of magnetic resonance imaging has improved our understanding of the pathophysiology and natural course of multiple sclerosis (MS). The ability of magnetic resonance imaging to show the evolution of MS lesions on sequential scans has brought it to be one of the endpoints in clinical trials for disease-modifying therapies. Based on the most updated consensus guidelines from the American (Consortium of MS Centers) and European (Magnetic Resonance Imaging in MS) boards of experts in MS, this document shows the most relevant landmarks related to imaging findings, diagnostic criteria, indications to obtain a magnetic resonance, scan protocols and sequence options for patients with MS. Although incorporating the knowledge derived from the research arena into the daily clinical practice is always challenging, in this article, the authors provide useful recommendations to improve the information contained in the magnetic resonance report oriented to facilitate communication between radiologists and specialized medical teams involved in MS patients' multidisciplinary care.

Can unenhanced MRI of the breast replace contrast-enhanced MRI in assessing response to neoadjuvant chemotherapy?

BACKGROUND

The goals of neoadjuvant chemotherapy (NAC) are to reduce tumor volume and to offer a prognostic indicator in assessing treatment response. Contrast-enhanced magnetic resonance imaging (CE-MRI) is an established method for evaluating response to NAC in patients with breast cancer.

PURPOSE

To validate the role of unenhanced MRI (ue-MRI) compared to CE-MRI for assessing response to NAC in women with breast cancer.

MATERIAL AND METHODS

Seventy-one patients with ongoing NAC for breast cancer underwent MRI before, during, and at the end of NAC. Ue-MRI was performed with T2-weighted sequences with iterative decomposition of water and fat and diffusion-weighted sequences. CE-MRI was performed using three-dimensional T1-weighted sequences before and after administration of gadobenate dimeglumine. Two blinded observers rated ue-MRI and CE-MRI for the evaluation of tumor response. Statistical analysis was performed to compare lesion size and ADC values changes during therapy, as well as inter-observer agreement.

RESULTS

There were no statistically significant differences between ue-MRI and CE-MRI sequences for evaluation of lesion size at baseline and after every cycle of treatment ( P > 0.05). The mean tumor ADC values at baseline and across the cycles of NAC were significantly different for the responder group.

CONCLUSION

Ue-MRI can achieve similar results to CE-MRI for the assessment of tumor response to NAC. ADC values can differentiate responders from non-responders.

Differences of radiocarpal cartilage alterations in arthritis and osteoarthritis using morphological and biochemical magnetic resonance imaging without gadolinium-based contrast agent administration

OBJECTIVES

To identify differences of radiocarpal cartilage alterations in osteoarthritis and arthritis using multiparametrical magnetic resonance imaging (MRI) comprising morphological and biochemical sequences without gadolinium-based contrast agent administration.

METHODS

In this prospective study, multiparametrical MRI of the radiocarpal cartilage was performed in 47 participants (mean age, 46.6 ± 17.6 years; min., 20 years; max., 79 years) on a 3 Tesla MRI. The cohort consisted of 11 patients suffering from arthritis, 10 patients with osteoarthritis, 14 patients after distal radius fracture, and 12 healthy volunteers. The radiocarpal cartilage was assessed using morphological (DESS, TrueFISP) and biochemical (T2*) MRI sequences without the application of intravenous contrast agent. The modified Outerbridge classification system for morphological and region-of-interest analyses for biochemical analysis was applied to assess the degree of cartilage damage in each patient before data were statistically tested for significant difference between the groups using a post hoc Tukey test.

RESULTS

In morphological imaging, cartilage damage was significantly more frequent in arthritis and osteoarthritis than in healthy volunteers (DESS: p = 0.01, p = 0.0004; TrueFISP: p = 0.02, p = 0.0001). In T2* imaging, patients with osteoarthritis showed higher cartilage damage compared to patients with arthritis (p = 0.01).

CONCLUSION

With multiparametrical MRI, it is possible to identify differences of radiocarpal cartilage alterations of patients with arthritis and osteoarthritis using the combination of morphological and biochemical MR imaging of the radiocarpal cartilage without the application of contrast agent. Multiparametrical MRI without the usage of contrast agent may be a potential tool helping to distinguish both entities.

KEY POINTS

• Multiparametrical MRI with morphological and biochemical sequences allows the differentiation of patients with arthritis and osteoarthritis. • High-resolution MRI of radiocarpal cartilage is possible without administration of contrast agent.

Spectral Computed Tomography Angiography With a Gadolinium-based Contrast Agent: First Clinical Imaging Results in Cardiovascular Applications

PURPOSE

Computed tomography angiography (CTA) requires IV application of iodine-based contrast agents. There are several medical conditions in which application is not advisable or even feasible, especially for elective examinations. Novel techniques such as monoenergetic reconstructions from dual-energy computed tomographic (CT) data have been shown to increase radiation attenuation of gadolinium (Gd)-based contrast agents in a phantom model. Therefore, the purpose of the present investigation was to evaluate the technical feasibility and image quality of clinical spectral CTA with a Gd-based contrast agent.

MATERIALS AND METHODS

Eleven consecutive patients with common indications for thoracic CTA and contraindications for iodine-based contrast agents were examined using clinical routine doses (0.2 mmol/kg) of Gd-based contrast agent with spectral CT. Monoenergetic reconstructions of the spectral data set were computed.

RESULTS

We performed 11 Gd-enhanced CTAs: 9 aortic angiographies, 1 coronary angiography, and 1 angiography of the pulmonary arteries. Image quality of the monoenergetic reconstructions with 40 keV (monoE40) was considered diagnostic by 2 experienced radiologists in each patient; the conventional CT reconstructions did not reach diagnostic image quality. MonoE40 reconstruction resulted in a substantial, ∼2-fold increase of intravascular Gd attenuation compared with the conventional images (P<0.0001). No relevant change of attenuation was observed for the myocardium or the skeletal muscle.

CONCLUSIONS

With spectral CT and reconstruction of monoenergetic images with extrapolated 40 keV, Gd-based contrast agent thoracic angiography with clinical doses of Gd is technically feasible. Gd-based CTA seems a valuable alternative in patients with contraindications for iodine-based contrast media.

Diagnostic Value of Diffusion-Weighted Imaging and Apparent Diffusion Coefficient in Assessment of the Activity of Crohn Disease: 1.5 or 3 T

Objective

The objective of this study is to evaluate the role of diffusion-weighted imaging (DWI) in assessment of the activity of Crohn disease (CD) and to explore differences between DWI in 3 T and 1.5 T.

Methods

Postcontrast magnetic resonance enterography with DWI of 72 patients with pathological proof of CD was retrospectively evaluated for restricted diffusion qualitatively and quantitavely in 3 T (n = 40) and 1.5 T (n = 32). Magnetic resonance activity score of 7 or higher was used as reference of activity.

Results

Fifty-five patients had active lesions. Diffusion-weighted imaging hyperintensity showed sensitivity (100%, 100%) and specificity (88.89%, 100%) in 1.5/3 T for activity assessment. Mean ± SD apparent diffusion coefficient for active lesions was 1.21 ± 0.42 and 1.28 ± 0.59 × 10⁻³ mm²/s in 1.5 and 3 T, respectively. The proposed cutoff values of 1.35 and 1.38 × 10⁻³ mm²/s in 1.5 and 3 T, respectively, had sensitivity (80%, 93%), specificity (100%, 90%), accuracy (88%, 93%), and no significant difference in accuracy between 1.5/3 T (P = 0.48).

Conclusions

Diffusion-weighted imaging hypersensitivity and apparent diffusion coefficient values accurately assessed the activity of CD. No significant statistical difference in diagnostic accuracy was detected between 1.5 and 3 T.

Time-resolved magnetic resonance angiography (TR-MRA) for the evaluation of post coiling aneurysms; A quantitative analysis of the residual aneurysm using full-width at half-maximum (FWHM) value

Magnetic resonance image (MRI) is now widely used for imaging follow-up for post coiling brain aneurysms. However, the accuracy on the estimation of residual aneurysm, which is crucial for the retreatment planning, remains to be controversial. The purpose of this study is to evaluate a new post-processing technique that provides improved estimation of the residual aneurysm after coil embolization. One hundred aneurysms on 93 patients who underwent coil embolization for brain aneurysm were evaluated using the 1.5 Tesla time-resolved magnetic resonance angiography (TR-MRA) one year after the treatment. To minimize the inter-observer variability caused by the window level adjustment, an automatic post processing protocol using the full-width at half-maximum (FWHM) value was utilized. The result was then compared with that from the conventional cerebral angiography. Of the 97 aneurysms that underwent both TR-MRA and DSA, 23 (23.7%) showed residual neck / dome during follow-up. After window level adjustment, the size of the parent artery in the TR-MRA was consistent with that in the DSA. The reconstructed Volume Rendering images provided clear contours of the residual aneurysms and contributed to the understanding the configuration of residual aneurysm. The largest and the smallest diameter of the residual aneurysms was larger in the TR-MRA than in the DSA (8.05 vs. 7.72 mm, p = 0.0004; 4.99 vs. 4.19 mm, p = 0.007 respectively). The sensitivity, specificity, and positive and negative predictive values of TR-MRA compared to DSA were 100%, 97%, 73%, and 100%, respectively. Using the FWHM value to optimize the window level adjustment, the size of the residual component observed in the TR-MRA was larger compared to that in the DSA whereas the size of neck and the parent artery showed consistency between the two modalities. This image processing technique can be used as an effective screening tool for evaluating residual component in post-coiling brain aneurysms.