Imaging of Bone Anatomical Variants Around the Foot and Ankle.

Different anatomical variants can be found in the ankle and foot, generally as occasional findings, although they can be the cause of diagnostic pitfalls and difficulties, especially in radiographic interpretation in trauma. These variants include accessory bones, supernumerary sesamoid bones, and accessory muscles. In most cases, they represent developmental anomalies found in incidental radiographic findings. This review discusses the main bony anatomical variants, including accessory and sesamoid ossicles, most commonly found in the foot and ankle that can be a cause of diagnostic challenges.

Cornerstones of CT urography: a shared document by the Italian board of urogenital radiology.

CT urography is a single term used to refer to different scanning protocols that can be applied for a number of clinical indications. If, on the one hand, this highlights the role of the radiologist in deciding the most suitable technique to perform according to the patient's needs, on the other hand, a certain confusion may arise due to the different technical and clinical variables that have to be taken into account. This has been well demonstrated by a previous work based on an online questionnaire administered to a population of Italian radiologists that brought out similarities as well as differences across the national country. Defining precise guidelines for each clinical scenario, although desirable, is a difficult task to accomplish, if not even unfeasible. According to the prementioned survey, five relevant topics concerning CT urography have been identified: definition and clinical indications, opacification of the excretory system, techniques, post-processing reconstructions, and radiation dose and utility of dual-energy CT. The aim of this work is to deepen and share knowledge about these main points in order to assist the radiology in the daily practice. Moreover, a synopsis of recommendations agreed by the Italian board of genitourinary imaging is provided.

Advanced MRI imaging of nerve roots in lumbar radiculopathy due to discoradicular conflict: DWI, DTI, and T2 mapping with clinical and neurophysiological correlations.

PURPOSE: To evaluate the lumbar nerve root alterations in patients with lumbar disc herniation sciatica using advanced multimodality MRI sequences and the correlations with clinical and neurophysiological findings. MATERIAL AND METHODS: We prospectively evaluated 45 patients suffering from unilateral lumbar radiculopathy due to disco radicular conflict. All patients underwent MRI examinations using a standard MRI protocol and additional advanced MRI sequences (DWI, DTI, and T2 mapping sequences). Relative metrics of ADC, FA, and T2 relaxation times were recorded by placing ROIs at the pre-, foraminal, and post-foraminal level, either at the affected side or the contralateral side, used as control. All patients were also submitted to electromyography testing, recording the spontaneous activity, voluntary activity, F wave amplitude, latency, and motor evoked potentials (MEP) amplitude and latency, both at the level of the tibialis anterior and the gastrocnemius. Clinical features (diseases duration, pain, sensitivity, strength, osteotendinous reflexes) were also recorded. RESULTS: Among clinical features, we found a positive correlation of pain intensity with ADC values of the lumbar nerve roots. The presence of spontaneous activity was correlated with lower ADC values of the affected lumbar nerve root. F wave and MEP latency were correlated with decreased FA values at the foraminal level and increased values at the post-foraminal level. The same neurophysiological measures correlated positively with pre-foraminal T2 mapping values and negatively with post-foraminal T2 mapping values. Increased T2 mapping values at the foraminal level were correlated with disease duration. CONCLUSIONS: Evaluation of lumbar nerve roots using advanced MRI sequences may provide useful clinical information in patients with lumbar radiculopathy, potentially indicating active inflammation/myelinic damage (DTI, T2 mapping) and axonal damage/chronicity (DWI).

MR imaging of cerebral involvement of Rosai-Dorfman disease: a single-centre experience with review of the literature.

Rosai-Dorfman disease (RDD) is a rare, benign, non-Langerhans cells histiocytosis with massive lymphadenopathy of uncertain aetiology. It is commonly characterized by massive, painless, non-tender, bilateral cervical lymphadenopathy. Extra-nodal involvement is usually seen in 50% of patients, with the brain being affected in only 5% of cases, usually as dural-based lesions. Clinical presentation is heterogeneous and strongly dependent on the localization of the lesions. Although the histopathological findings are essential for the final diagnosis, brain magnetic resonance imaging (MRI) currently represents the first-line strategy for the detection of the lesions across the central nervous system (CNS); moreover, it may provide additional elements for the differential diagnosis versus other more common lesions. We performed a case-based literature review to highlight possible aetiologic and pathogenetic theories of this disease, along with imaging features of RDD, with a particular focus on the MRI characteristics of the CNS involvement (CNS-RDD). Finally, we provided a novel insight on the current therapeutic approaches, either surgical or medical.

Real-world clinical validity of cardiac magnetic resonance tissue tracking in primitive hypertrophic cardiomyopathy.

OBJECTIVE: Cardiac magnetic resonance (CMR) is an uncontested diagnostic tool for identifying and assessing hypertrophic cardiomyopathy (HCM) patients. Concerning the necessity to identify valid prognosticators for predicting the individual risk of clinical evolution, this study aimed to evaluate the clinical validity of CMR tissue tracking (TT) analysis in patients affected by primitive HCM in a real-world setting. METHODS: This historical prospective study included 33 patients. Diagnostic validity and clinical validation were assessed for strain values. CMR-TT diagnostic validity was studied comparing HCM patients with healthy control groups and phenotypic presentation of HCM. The impact of strain values and all phenotypic disease characteristics were assessed in a long-term follow-up study. RESULTS: The inter-reading agreement was good for all strain parameters. Significant differences were observed between the control group and HCM patients. Similarly, hypertrophic and LGE + segments showed lower deformability than healthy segments. The AUC of predictive model, including conventional risk factors for MACE occurrence and all strain values, reached 98% of diagnostic concordance (95% CI .94-1; standard error: .02; p value .0001), compared to conventional risk factors only (86%; 95% CI .73-99; standard error: .07; p value .002). CONCLUSION: In patients with primitive HCM, CMR-TT strain proves high clinical validity providing independent and non-negligible prognostic advantages over clinical features and traditional CMR markers.

Multimodality imaging in chronic heart failure.

The prevalence of heart failure (HF) is approximately 1-2% of the adult population in developed countries, rising to ≥ 10% among people over 70. The common symptoms of HF include shortness of breath, ankle swelling and fatigue, determined by a reduced cardiac output. Multimodality imaging is crucial to define HF etiology, determine prognosis and guiding tailored treatments. Echocardiography is the most widely used imaging modality and maintains a pivotal role in the initial diagnostic work-up and in the follow-up of HF patients. Cardiac magnetic resonance (CMR) may support the morpho-functional assessment provided by echocardiography when the acoustic window is limited or a gold standard evaluation is required. Furthermore, CMR is frequently used due to the unmatched capability to characterize myocardial structure. Coronary computed tomography angiography has become the non-invasive imaging of choice to diagnose or rule-out coronary artery disease, acquiring remarkable importance in the management of HF patients. Moreover, emerging capabilities of CT-based tissue characterization may be useful, especially when CMR is contraindicated. Finally, chest CT may contribute to precisely define the framework of HF patients, revealing new insight about cardiopulmonary pathophysiological interactions with potential high prognostic value.

T2-mapping MRI evaluation of patellofemoral cartilage in patients submitted to intra-articular platelet-rich plasma (PRP) injections.

This study evaluated the ability of T2 mapping magnetic resonance imaging at 3 T, in addition to morphological sequences, to assess efficacy of platelet-rich plasma (PRP) injections, characterizing qualitatively and quantitatively the grade of knee cartilage repair in patients with patellofemoral chondropathy. We retrospectively studied 34 patients (22 men, 12 women, mean age 41.8 years, including 22 men) with patellofemoral knee chondropathy, who underwent intra-articular PRP injections and completed a clinical and instrumental follow-up. As control group, we evaluated 34 patients who underwent non-operative therapy. All patients were submitted to clinical (using VAS and WOMAC index) and imaging studies with 3 T magnetic resonance with cartilage analysis with T2 mapping sequences for cartilage analysis before and after treatment. In the study group, mean pre-treatment T2 relaxation time values were 44.2 ± 2.5 ms, considering all articular cartilage compartments, with significant reduction at the follow-up (p < 0.001). At the index compartment, mean pre-treatment T2 relaxation times values were 47.8 ± 3.6 ms, with statistically significant reduction at the follow-up (p < 0.001). Evaluation of focal cartilage lesions reported pre-treatment mean T2 value of 70.1 ± 13.0 ms and post-treatment mean value of 59.9 ± 4.6 ms (p < 0.001). From a clinical point of view, the pre-treatment WOMAC and VAS scores were 18.3 ± 4.5 and 7 (IQR:6-7.2), respectively; the post-treatment values were 7.3 ± 3.2 and 2 (IQR: 1.7-3.0), respectively (p < 0.001). In the control group, despite clinical improvement, we didn't find significant T2 values change during the follow-up period. In conclusion, T2 mapping is a valuable indicator for chondropathy and treatment-related changes over time.

Appropriate use criteria for cardiovascular magnetic resonance imaging (CMR): SIC-SIRM position paper part 1 (ischemic and congenital heart diseases, cardio-oncology, cardiac masses and heart transplant).

Cardiac magnetic resonance (CMR) has emerged as new mainstream technique for the evaluation of patients with cardiac diseases, providing unique information to support clinical decision-making. This document has been developed by a joined group of experts of the Italian Society of Cardiology and Italian society of Radiology and aims to produce an updated consensus statement about the current state of technology and clinical applications of CMR. The writing committee consisted of members and experts of both societies who worked jointly to develop a more integrated approach in the field of cardiac radiology. Part 1 of the document will cover ischemic heart disease, congenital heart disease, cardio-oncology, cardiac masses and heart transplant.

Evaluation of intervertebral disc using T2 mapping sequences in patients undergoing O2-O3 chemiodiscolysis: an instrumental study with clinical correlation.

PURPOSE: To assess the MRI modifications of the intervertebral disc (IVD) treated by chemiodiscolysis using T2 mapping sequences. METHODS: Thirty sciatica patients (17 males, 13 females, mean age 47.52 years) were enrolled for percutaneous CT-guided O2-O3 chemiodiscolysis treatment. As a control group, we enrolled 30 patients who were treated by CT-guided periradicular injections. All patients were submitted to clinical (using VAS and Oswestry Disability index (ODI)) and imaging studies to evaluate the intervertebral disc area (IDA) and T2 mapping values of the IVD before and at 1-month follow-up. RESULTS: In the study group, pre-treatment IDA mean values were 20.47 ± 1.62 cm2, with significant reduction at the follow-up (P < 0.05). Mean pre-treatment T2 relaxation time values were 38.80 ± 4.51 ms, 44.05 ± 0.91 ms, and 45.45 ± 14.11 ms for anterior annulus fibrosus, nucleus pulposus (NP), and posterior annulus fibrosus, respectively, with significant increase at the level of the NP (P < 0.05) at the follow-up. Mean pre-treatment ODI and VAS scores were 21.5 ± 10.6 and 8.5 ± 0.57, with significant improvement at the post-treatment follow-up (P < 0.05). In the control group, despite clinical improvement, we did not find significant IVA reduction nor significant T2 values change after treatment. Correlation analysis of T2 mapping relaxation time values showed significant correlation of NP T2 mapping value with both the reduction of IDA (0.81, P < 0.001) and the improvement of VAS and ODI scores (0.86, P < 0.001) at 1 month. In the control group, we did not find any statistically significant correlation. CONCLUSIONS: T2 mapping may be a useful indicator to predict disc shrinkage and the clinical response to CT-guided O2-O3 injection.

The sub-millisievert era in CTCA: the technical basis of the new radiation dose approach.

Computed tomography coronary angiography (CTCA) has become a cornerstone in the diagnostic process of the heart disease. Although the cardiac imaging with interventional procedures is responsible for approximately 40% of the cumulative effective dose in medical imaging, a relevant radiation dose reduction over the last decade was obtained, with the beginning of the sub-mSv era in CTCA. The main technical basis to obtain a radiation dose reduction in CTCA is the use of a low tube voltage, the adoption of a prospective electrocardiogram-triggering spiral protocol and the application of the tube current modulation with the iterative reconstruction technique. Nevertheless, CTCA examinations are characterized by a wide range of radiation doses between different radiology departments. Moreover, the dose exposure in CTCA is extremely important because the benefit-risk calculus in comparison with other modalities also depends on it. Finally, because anatomical evaluation not adequately predicts the hemodynamic relevance of coronary stenosis, a low radiation dose in routine CTCA would allow the greatest use of the myocardial CT perfusion, fractional flow reserve-CT, dual-energy CT and artificial intelligence, to shift focus from morphological assessment to a comprehensive morphological and functional evaluation of the stenosis. Therefore, the aim of this work is to summarize the correct use of the technical basis in order that CTCA becomes an established examination for assessment of the coronary artery disease with low radiation dose.

Coronary artery disease (CAD) extension-derived risk stratification for asymptomatic diabetic patients: usefulness of low-dose coronary computed tomography angiography (CCTA) in detecting high-risk profile patients.

BACKGROUND: As one of the most frequent risk factors for cardiovascular disease, type 2 diabetes mellitus (T2DM) is one of the largest causes of death. However, an acute cardiac presentation is not uncommon in diabetic patients, and the current investigative approach remains often inadequate. The aim of our study was to retrospectively stratify the risk of asymptomatic T2DM patients using low-dose 640-slice coronary computed tomography angiography (CCTA). MATERIALS AND METHODS: CCTA examinations of 62 patients (mean age, 65 years) with previous diagnosis of type 2 diabetes and without cardiac symptoms were analyzed. Image acquisition was performed using a 640-slice CT. Per-patient, per-vessel and per-plaque analyses were performed. Stratification risk was evaluated according to the ESC guidelines. The patients were followed up after 2.21 ± 0.56 years from CCTA examination. RESULTS: Coronary artery disease (CAD) was found in 58 patients (93.55%) presenting 290 plaques. Analysis of all samples showed severe-to-occlusive atherosclerosis in 24 patients (38.7% of cases). However, over the degree of stenosis, 23 patients were evaluated at high risk considering the extension of CAD. Good agreement was shown by the correlation of CAD extension/risk estimation and MACE incidence, according to a Kaplan-Meier survival analysis (p value = 0.001), with a 7.25-fold increased risk (HR 7.25 CI 2.13-24.7; p value = 0.002). CONCLUSION: Our study confirms the high capability of CCTA to properly stratify the CV risk of asymptomatic T2DM patients. Its use could be recommended if we consider how current investigative strategies to correctly assess these patients often seem inadequate.

In vivo radiation dosimetry and image quality of turbo-flash and retrospective dual-source CT coronary angiography.

PURPOSE: To compare measured radiation dose (MD), estimated radiation dose (ED) and image quality in coronary computed tomography between turbo-flash (TFP) and retrospective protocol (RP) and correlate MD with size-specific dose estimates (SSDE). MATERIALS AND METHODS: In this prospective study, we selected 68 patients (mean age, 59.2 ± 9.7 years) undergoing 192 × 2 dual-source CT (SOMATOM Force, Siemens) to rule out coronary artery disease. Thirty-one underwent TFP and 37 RP. To evaluate in vivo MD, thermoluminescent dosimeters were placed, superficially, at thyroid and heart level, left breast areola and left hemi-thorax. MD in each site, and ED parameters, such as volume CT dose index (CTDIvol), SSDE, dose length product (DLP), effective dose (E), were compared between two protocols with a t test. Image quality was compared between two protocols. Inter-observer agreement was evaluated with a kappa coefficient (k). In each protocol, MD was correlated with SSDE using a Pearson coefficient (r). RESULTS: Comparing TFP and RP, MD at thyroid (1.43 vs. 2.58 mGy; p = 0.0408), heart (3.58 vs. 28.72 mGy; p < 0.0001), left breast areola (3.00 vs. 24.21 mGy; p < 0.0001) and left hemi-thorax (2.68 vs. 24.03 mGy; p < 0.0001), CTDIvol, SSDE, DLP and E were significantly lower. Differences in image quality were not statistically significant. Inter-observer agreement was good (k = 0.796) in TFP and very good (k = 0.817) in RP. MD and SSDE excellently correlated with TFP (r = 0.9298, p < 0.0001) and RP (r = 0.9753, p < 0.0001). CONCLUSIONS: With TFP, MD, CTDIvol, SSDE, DLP and E were significantly lower, than with RP. Image quality was similar between two protocols. MD correlated excellently with SSDE in each protocol.

Cardiac magnetic resonance in arrhythmogenic cardiomyopathies.

Over the past few years, the approach to the 'arrhythmic patient' has profoundly changed. An early clinical presentation of arrhythmia is often accompanied by non-specific symptoms and followed by inconclusive electrocardiographic findings. In this scenario, cardiac magnetic resonance (CMR) has been established as a clinical tool of fundamental importance for a correct prognostic stratification of the arrhythmic patient. This technique provides a high-spatial-resolution tomographic evaluation of the heart, which allows studying accurately the ventricular volumes, identifying even segmental kinetic anomalies and properly detecting diffuse or focal tissue alterations through an excellent tissue characterization, while depicting different patterns of fibrosis distribution, myocardial edema or fatty substitution. Through these capabilities, CMR has a pivotal role for the adequate management of the arrhythmic patient, allowing the identification of those phenotypic manifestations characteristic of structural heart diseases. Therefore, CMR provides valuable information to reclassify the patient within the wide spectrum of potentially arrhythmogenic heart diseases, the definition of which remains the major determinants for both an adequate treatment and a poor prognosis. The purpose of this review study was to focus on the role of CMR in the evaluation of the main cardiac clinical entities associated with arrhythmogenic phenomena and to present a brief debate on the main pathophysiological mechanisms involved in the arrhythmogenesis process.

Weight-bearing MR Imaging of Knee, Ankle and Foot.

Clinical management of several pathologies of the lower extremity joint relies on instrumental imaging evaluation. The assessment of joint changes with physiologic load requires studies using positions with the patient standing. Weight-bearing radiographs are the mainstay for the evaluation of several conditions such as knee osteoarthritis, pes planus, and hallux valgus, in particular to obtain measurements of articular parameters, especially for presurgical studies. In the last few years, dedicated magnetic resonance imaging and computed tomography scanners have also been developed to obtain high-resolution, multiplanar, and sectional images of the lower extremity joints during weight-bearing. These techniques provide detailed information on joint structure modifications under load in both physiologic and pathologic conditions to improve the diagnostic accuracy of weight-bearing studies.

Modic I changes size increase from supine to standing MRI correlates with increase in pain intensity in standing position: uncovering the "biomechanical stress" and "active discopathy" theories in low back pain.

PURPOSE: To evaluate the relationship between degenerative disc, endplate Modic changes (MC) type I, and pain during upright weight-bearing MRI scan of the lumbar spine in a cohort of patients with non-specific low back pain. MATERIALS AND METHODS: We evaluated 38 patients with non-specific low back pain and MRI evidence of Modic I vertebral changes. The patients were evaluated in a standard and upright weight-bearing position using a dedicated MR unit. The extent of endplate MC type I, intervertebral disc height at the involved level, and degree of degeneration in the same intervertebral disc were compared. Pain was assessed through the VAS questionnaire. RESULTS: In the upright position, the area of Modic I changes increased in 26 patients (68.4%, p ≤ 0.001) compared to the supine position. In the upright position, reduction in the disc height was found in 35 patients (92.1%). Correlation analysis showed moderate negative correlation (ρ = - 0.45) between intervertebral disc height and increase in the area of Modic I changes, and weak positive correlation (ρ = 0.12) between Pfirrmann grade and increase in the area of Modic I changes. At clinical evaluation, 30 patients (78.9%) reported worsening of low back pain standing in the upright position. Increase in VAS values on the upright position correlated significantly (ρ = 0.34) with an increase in the area of Modic I changes. CONCLUSIONS: Our results showed the modifications of Modic I changes under loading, with MRI evidence of increased MC area extent in the upright position and correlation between Modic changes extension increase and increase in pain in the standing position. Weight-bearing MRI scans represent a valuable complement to standard sequences since they provide the radiologist with additional diagnostic information about low back pain. These slides can be retrieved from Electronic Supplementary Material.

Advanced magnetic resonance imaging (MRI) of soft tissue tumors: techniques and applications.

Imaging evaluation of soft tissue tumors is important for the diagnosis, staging, and follow-up. Magnetic resonance imaging (MRI) is the preferred imaging modality due to its multiplanarity and optimal tissue contrast resolution. However, standard morphological sequences are often not sufficient to characterize the exact nature of the lesion, addressing the patient to an invasive bioptic examination for the definitive diagnosis. The recent technological advances with the development of functional MRI modalities such as diffusion-weighted imaging, dynamic contrast-enhanced perfusion imaging, magnetic resonance spectroscopy, and diffusion tensor imaging with tractography have implemented the multiparametricity of MR to evaluate in a noninvasive manner the biochemical, structural, and metabolic features of tumor tissues. The purpose of this article is to review the state of the art of these advanced MRI techniques, with focus on their technique and clinical application.

Role of interventional radiology in the management of musculoskeletal soft-tissue lesions.

The lesions of the soft tissues are rare and extremely heterogeneous; even if the surgical treatment is usually the standard therapy, the role of the interventional radiology (IR) in this field is growing up for multiple reasons. First, because the imaging alone usually is not able to ensure a definitive diagnosis, IR has a basic role in the staging: the percutaneous biopsy is infact an irreplaceable step. Moreover, biopsy is necessary not only for histologic evaluations but also for the biochemical and molecular studies. Furthermore, the proved safety and effectiveness of IR in a multiple oncologial applications prompt a wider use also in this field.

New advances in MRI diagnosis of degenerative osteoarthropathy of the peripheral joints.

Degenerative osteoarthropathy is one of the leading causes of the pain and disability from musculoskeletal disease in the adult population. Magnetic resonance imaging (MRI) allows optimal visualization of all tissues involved in degenerative osteoarthritis disease process, mainly the articular cartilage. In addition to qualitative and semiquantitative morphologic assessment, several MRI-based advanced techniques have been developed to allow characterization and quantification of the biochemical cartilage composition. These include quantitative analysis and several compositional techniques (T1 and T2 relaxometry measurements and mapping, sodium imaging, delayed gadolinium-enhanced MRI of cartilage dGEMRIC, glycosaminoglycan-specific chemical exchange saturation transfer gagCEST, diffusion-weighted imaging DWI and diffusion tensor imaging DTI). These compositional MRI techniques may have the potential to serve as quantitative, reproducible, noninvasive and objective endpoints for OA assessment, particularly in diagnosis of early and pre-radiographic stages of the disease and in monitoring disease progression and treatment effects over time.

Carotid artery plaque characterization with a wide-detector computed tomography using a dedicated post-processing 3D analysis: comparison with histology.

PURPOSE: The characterization of atherosclerotic carotid plaque plays a key role in the identification of patients at risk. The aim of our work was to evaluate the potentialities of carotid computed tomography angiography (CCTA) in assessing composition of atherosclerotic plaque. MATERIALS AND METHODS: We retrospectively evaluated 29 patients (7 women and 22 men, age range 54-81; mean age 69) who underwent carotid endarterectomy. All patients underwent pre-surgical CCTA using a 320-slice scanner. Post-processing reconstructions and analysis were performed using a specific software. Percentage of three different components of the atherosclerotic plaque (adipose, fibrotic and calcific) were classified based on Hounsfield unit values. Post-processing results were compared with histological analysis. Vessel and plaque parameters were compared using the Pearson correlation coefficient (r). Bland-Altman plots with 95% confidence intervals were calculated for correlation. McNemar's test was used for comparison of dichotomous variables. RESULTS: A significant correlation between histology and CCTA was found with respect to the areas corresponding to adipose, fibrotic and calcified plaques. The existence of proportional bias was observed between the two quantifying methods with lower discrepancies found for the adipose and fibrotic plaque areas. The Bland-Altman analyses showed a mean bias of 3.2%, 2.5% and 0.6% between histology and CCTA, for adipose, fibrotic and calcified plaque areas, respectively. CONCLUSIONS: Multi-detector CT angiography represents a valuable technique to assess quantitatively the composition of atherosclerotic plaques, with particular reference to the prevalence of fibrotic tissue, and is a useful diagnostic tool to improve risk stratification of patients for cerebral stroke.

Effects of serial macrocyclic-based contrast materials gadoterate meglumine and gadobutrol administrations on gadolinium-related dentate nuclei signal increases in unenhanced T1-weighted brain: a retrospective study in 158 multiple sclerosis (MS) patients.

PURPOSE: To perform T1 signal intensity (SI) measurements in the dentate nuclei of adult patients with confirmed multiple sclerosis (MS) after serial administrations of the macrocyclic gadolinium-based contrast agents (GBCAs), gadoterate meglumine and gadobutrol. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board and informed consent was waived. A review of our PACS database for the period from March 1, 2007 to July 31, 2016 revealed 158 confirmed MS patients who received exclusively either gadoterate meglumine (n = 81) or gadobutrol (n = 77) for diagnosis and follow-up. SI measurements on unenhanced T1-weighted images were performed on all scans of all patients and at regions of interest (ROIs) positioned on the dentate nucleus (DN) and pons. The dentate nucleus-to-pons (DNP) T1-SI ratio was subsequently calculated. Unpaired T test and regression analysis were used to evaluate statistical differences. RESULTS: An increase in DNP was noted between the first and last MR examinations for both gadoterate meglumine (0.0032 ± 0.0216) and gadobutrol (0.0019 ± 0.0346). Although the differences were not statistically significant based across the entire patient population, visible T1 hyperintensity in the DN was noted in approximately one-third of all patients in each group that received at least five administrations of either GBCA. CONCLUSIONS: SI increases on unenhanced T1-weighted images possibly indicative of gadolinium retention occur after serial administrations of the macrocyclic GBCAs, gadoterate meglumine and gadobutrol.