Use Of Contrast-enhanced MRI Research Articles

Adenomas hipofisarios no funcionantes. Incidentaloma hipofisario

Non-functioning pituitary adenomas (NFPAs) are tumors of the pituitary gland that are usually benign and show no clinical or biochemical signs of excessive hormone production. These tumors manifest clinically when they are large enough to exert pressure on surrounding structures. Among pituitary incidentaloma, NFPAs are the most common, as they are often diagnosed accidentally during imaging tests performed for other reasons. To properly evaluate these tumors and their relationship to other structures, the use of contrast-enhanced MRI is preferred. In addition, it is necessary to perform a hormonal analysis to rule out hormonal alterations and a neuro-ophthalmological examination in those cases in which the adenomas are close to the optic chiasm or cavernous sinuses, or in patients who present vision problems. In cases where the tumors are symptomless, observation is an option. However, transsphenoidal surgery is the first-line treatment for patients with symptoms or large tumors. Other options include radiation therapy and medical treatment with dopaminergic agonists and other drugs that are being explored more recently.

Advancing Uterine Cancer Care: Transvaginal Ultrasonography in Preoperative Staging Analysis

Objective: To determine the role of transvaginal ultrasonography in the preoperative staging of uterine cancer. Methods: The research included 110 women who had been diagnosed with endometrial malignancy by histological confirmation, whichwas achieved through procedures such as dilation and curettage, hysteroscopy, or endometrial biopsy. Additionally, women who had ahigh suspicion of endometrial malignancy based on imaging results and were scheduled for surgery as their main therapy were alsoeligible to participate in the study. Results: A total of 110 individuals satisfied the criteria for inclusion in the research, with an average age of 49.89 ± 2.99 years. In relation to the extent of myometrial invasion, our study yielded sensitivity rates of 81%, 81%, and 69% for the subjective, Gordon, and Karlssontechniques, respectively. The corresponding specificity rates were found to be 67%, 60%, and 81% for the same approaches. The subjective, Gordon, and Karlsson techniques yielded corresponding overall accuracies of 74%, 70%, and 75%. The use of contrast-enhanced MRI yielded a sensitivity, specificity, and overall accuracy of 94%, 72%, and 84%, respectively, in the assessment of myometrial invasion. In the assessment of cervical stromal invasion, the ultrasound subjective technique showed a sensitivity of 33% and a specificity of 99%. On the other hand, the objective method yielded a sensitivity of 52% and a specificity of 92%. The total accuracy for both methods was determined to be 90% and 83% respectively. The use of contrast-enhanced MRI yielded a sensitivity, specificity, and overall accuracy of 69%, 100%, and 96% respectively in detecting cervical involvement. Conclusion: We concluded that the utilisation of pelvic ultrasound in the preoperative staging of endometrial cancer holds significantvalue. It demonstrates a notable sensitivity in evaluating myometrial invasion, exhibiting a reasonable to moderate level of concordancewith MRI. Furthermore, it exhibits a superior, albeit still moderate, level of agreement with MRI in assessing cervical invasion.

Use of Gadoxetic Acid-enhanced Liver MRI and Mortality in More than 30 000 Patients with Hepatocellular Carcinoma: A Nationwide Analysis.

Background The impact on survival of gadoxetic acid-enhanced MRI in addition to multiphase contrast material-enhanced CT for initial staging in patients with hepatocellular carcinoma (HCC) is unknown. Purpose To compare all-cause mortality in patients with HCC who underwent CT only, CT plus non-gadoxetic acid-enhanced MRI, or CT plus gadoxetic acid-enhanced MRI as part of their initial diagnostic work-up. Materials and Methods The authors performed a nationwide retrospective cohort study of patients diagnosed with HCC in South Korea between January 2008 and December 2010. Follow-up extended through December 2014. The primary outcome was all-cause mortality. Cox proportional hazards regression model with adjustment of confounding factors was used to estimate hazard ratios (HRs) for all-cause mortality. Results Among 30 023 patients with HCC (mean age ± standard deviation, 58.5 years ± 10.7, 23 978 men), the proportions of patients in whom HCC was diagnosed using CT only, CT plus non-gadoxetic acid-enhanced MRI, and CT plus gadoxetic acid-enhanced MRI were 56.1%, 12.9%, and 31.0%, respectively. In adjusted analysis using CT only as the reference category, the HR for mortality for CT plus gadoxetic acid-enhanced MRI was 0.64 (95% confidence interval [CI]: 0.62, 0.67; P < .001), and the HR for CT plus non-gadoxetic acid-enhanced MRI was 0.71 (95% CI: 0.68, 0.75; P < .001). Use of CT plus gadoxetic acid-enhanced MRI was associated with lower mortality compared with CT plus non-gadoxetic acid-enhanced MRI (adjusted HR, 0.90; 95% CI: 0.85, 0.95; P < .001), but this survival advantage was restricted to patients with localized disease. Conclusion In patients with hepatocellular carcinoma, additional use of contrast-enhanced MRI was associated with lower mortality. Furthermore, CT plus gadoxetic acid-enhanced MRI was associated with better survival than CT plus non-gadoxetic acid-enhanced MRI but only in patients with localized disease. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Kim in this issue.

Treatment monitoring of immunotherapy and targeted therapy using FET PET in patients with melanoma and lung cancer brain metastases: Initial experiences.

e13525 Background: Due to the lack of specificity of contrast-enhanced (CE) MRI, the differentiation of progression from pseudoprogression (PsP) following immunotherapy using checkpoint inhibitors (IT) or targeted therapy (TT) may be challenging, especially when IT or TT is applied in combination with radiotherapy (RT). Similarly, for response assessment of RT plus IT or targeted therapy (TT), the use of CE MRI alone may also be difficult. For problem solving, the integration of advanced imaging methods may add valuable information. Here, we evaluated the value of amino acid PET using O-(2-[18F]fluoroethyl)-L-tyrosine (FET) in comparison to CE MRI for these important clinical situations in patients with brain metastases (BM) secondary to malignant melanoma (MM) and non-small cell lung cancer (NSCLC). Methods: From 2015-2018, we retrospectively identified 31 patients with 74 BM secondary to MM (n = 20 with 42 BM) and NSCLC (n = 11 with 32 BM) who underwent 52 FET PET scans during the course of disease. All patients had RT prior to IT or TT initiation (61%) or RT concurrent to IT or TT (39%). In 13 patients, FET PET was performed for treatment response assessment of IT or TT using baseline and follow-up scans (median time between scans, 4.2 months). In the remaining 18 patients, FET PET was used for the differentiation of progression from PsP related to RT plus IT or TT. In all BM, metabolic activity on FET PET was evaluated by calculation of tumor/brain ratios. FET PET imaging findings were compared to CE MRI and correlated to the clinical follow-up or neuropathological findings after neuroimaging. Results: In 4 of 13 patients (31%), FET PET provided additional information for treatment response evaluation beyond the information provided by CE MRI alone. Furthermore, responding patients on FET PET had a median stable clinical follow-up of 10 months. In 10 of 18 patients (56%) with CE MRI findings suggesting progression, FET PET detected PsP. In 9 of these 10 patients, PsP was confirmed by a median stable clinical follow-up of 11 months. Conclusions: FET PET may add valuable information for treatment monitoring in individual BM patients undergoing RT in combination with IT or TT.

Use of Contrast-Enhanced MRI in Management of Discordant Core Biopsy Results.

OBJECTIVE. Evaluating concordance between core biopsy results and imaging findings is an integral component of breast intervention. Pathologic results deemed benign discordant reflect concern that a malignancy may have been incorrectly sampled. Standard of care currently is surgical excision, although a large percentage of these lesions will be benign at final pathologic analysis. The purpose of this study was to determine whether inclusion of contrast-enhanced MRI would optimize patient care. MATERIALS AND METHODS. Forty-five patients with 46 lesions were identified who underwent contrast-enhanced MRI after receiving discordant ultrasound or stereotactic biopsy results between 2012 and mid 2018. These findings were classified BI-RADS category 4 at diagnostic imaging. Disease-positive was defined as all malignancies and borderline lesions. RESULTS. Fourteen patients had suspicious MRI findings; 31 patients did not. Negative or benign MRI findings were validated by stability at imaging follow-up of at least 1 year in 27 patients (28 lesions) and at least 6 months in four patients. Eight of the total of 46 discordant lesions were ultimately malignant, a rate of 17.3%, an expected result for BI-RADS 4 lesions. Sensitivity, specificity, positive predictive value, and negative predictive value of MRI calculated in the group of 41 patients (42 lesions) with documented stability for at least 1 year were 100%, 93.3%, 85.7%, and 100%. The false-negative rate of MRI was 0%; the false-positive rate was 2 of 30 (6.7%). CONCLUSION. In the management of discordant benign core biopsy results, contrast-enhanced MRI facilitated successful triage of patients to surgery; 31 of the original 45 patients (68.9%) avoided surgery.

Neuroblastoma and nephroblastoma: a radiological review.

Neuroblastoma (NBL) is the most common extra-cranial tumour in childhood. It can present as an abdominal mass, but is usually metastatic at diagnosis so the symptomatology can be varied. Nephroblastoma, also more commonly known as a Wilms tumour, is the commonest renal tumour in childhood and more typically presents as abdominal pathology with few constitutional symptoms, although rarely haematuria can be a presenting feature. The pathophysiology and clinical aspects of both tumours including associated risk factors and pathologies are discussed. Oncogenetics and chromosomal abnormalities are increasingly recognised as important prognostic indicators and their impact on initial management is considered. Imaging plays a pivotal role in terms of diagnosis and recent imaging advances mean that radiology has an increasingly crucial role in the management pathway. The use of image defined risk factors in neuroblastoma has begun to dramatically change how this tumour is characterised pre-operatively. The National Wilms Tumour Study Group have comprehensively staged Wilms tumours and this is reviewed as it impacts significantly on management. The use of contrast-enhanced MRI and diffusion-weighted sequences have further served to augment the information available to the clinical team during initial assessment of both neuroblastomas and Wilms tumours. The differences in management strategies are outlined. This paper therefore aims to provide a comprehensive update on these two common paediatric tumours with a particular emphasis on the current crucial role played by imaging.

Use of contrast-enhanced MRI of the heart in detection of risk of supraventricular tachyarrhythmias in patients with recent myocardial infarction

Methods Twenty persons (all males but two, as old as 57 ± 7 years) with recent (< 4 months) myocardial infarction of left ventricle were included. Paramagnetic contrast-enhanced T1weighted SE (TR=450-600 ms, TE=15-20 ms) MRI of the heart has been employed for visual detection of risk as well of anatomic locations of atrial arrhythmias in twenty patients with previous myocardial infarction. Contrast enhancement was carried out using intravenous injection of widely available extracellular paramagnetics in a dose as high as 2 ml of 0,5 M solution per 10 kg of body mass (BM). Two groups were separated in accordance with the electrophysiologic and clinical data. The Group 1 included eight persons without supraventricular tachycardias (SVT) in the course of follow-up for four months, and the Group 2 comprised twelve patients with frequent SVT paroxysms, all were later suggested for maze procedure. Also eight persons were recruited to the control group, all without cardiac pathology.

O7.05 * DIFFERENTIATION OF LOCAL RECURRENT BRAIN METASTASIS FROM RADIATION-INDUCED CHANGES USING O-(2-[18F]FLUOROETHYL)-L-TYROSINE PET

BACKGROUND: The aim of this study was to investigate the potential of O-(2-[18F]fluoroethyl)-L-tyrosine (18F-FET) PET for differentiating local recurrent brain metastasis from radiation-induced changes after radiation therapy since the use of contrast-enhanced MRI for this issue is often difficult. METHODS: 38 patients (mean age, 54 ± 11 y) with single or multiple contrast-enhancing brain lesions (n = 49) on MRI after radiation therapy of brain metastases were investigated with dynamic 18F-FET PET. Maximum and mean tumor/brain ratios (20-40 min postinjection) (TBRmax, TBRmean) of 18F-FET uptake were determined. Time activity curves (TAC) were generated and the time-to-peak (TTP) was calculated. Furthermore, TACs of each lesion were assigned to one of the following curve patterns: (I) constantly increasing 18F-FET uptake; (II) 18F-FET uptake peaking early (TTP ≤ 20 min) followed by a plateau; and (III) 18F-FET uptake peaking early (TTP ≤ 20 min) followed by a constant descent. The diagnostic accuracy of the TBRmax and TBRmean of 18F-FET uptake and the curve patterns for the correct identification of recurrent brain metastasis was evaluated by receiver-operating-characteristic (ROC) analyses using subsequent histological analysis (17 lesions in 16 patients) or clinical course and MR imaging findings (32 lesions in 22 patients) as reference. RESULTS: Both TBRmax and TBRmean were significantly higher in patients with recurrent metastasis (n = 25) than in patients with radiation-induced changes (n = 24) (TBRmax 3.3 ± 1.0 vs. 2.3 ± 0.4, P < 0.001; TBRmean 2.2 ± 0.4 vs. 1.7 ± 0.1, P < 0.001). The sensitivity/specificity of 18F-FET PET for the correct identification of recurrent brain metastases was 84 / 79% using TBRmax (area under the curve, 0.851 ± 0.06, cut-off 2.6; P < 0.001), 92/83% using TBRmean (area under the curve, 0.901 ± 0.05, cut-off 1.9; P < 0.001), and 84/100% for curve patterns II and III vs. curve pattern I (P < 0.001). Highest sensitivity/specificity (96/88%) to diagnose local recurrent metastasis was obtained when both a TBRmean ≥1.9 and curve pattern II or III were present (area under the curve, 0.963 ± 0.03; P < 0.001). CONCLUSION: Our findings suggest that the combined evaluation of the TBRmean of 18F-FET uptake and the pattern of TAC can differentiate local brain metastasis recurrence from radiation-induced changes with high accuracy. 18F-FET PET may thus contribute significantly to the management of patients with brain metastases.

Diagnostic performance of contrast-enhanced MR for acute appendicitis and alternative causes of abdominal pain in children

Unenhanced MRI has emerged as a useful tool for diagnosing pediatric acute appendicitis. The use of contrast-enhanced MRI for diagnosing pediatric appendicitis has not been documented. The purpose of this study is to examine the diagnostic performance of contrast-enhanced MRI for acute appendicitis and alternative entities in the pediatric population presenting with acute abdominal pain. A retrospective review was conducted of 364 consecutive pediatric patients undergoing contrast-enhanced MRI for the evaluation of possible appendicitis at a single institution between November 2012 and September 2013. There were 132 cases of pathologically confirmed appendicitis out of 364 pediatric patients (36.3%) included in the study. Overall sensitivity and specificity were 96.2% (95% CI [91.4-98.4%]) and 95.7% (95% CI [92.3-97.6%]), respectively. Positive predictive value and negative predictive value were 92.7% (95% CI [86.6-96.3%]) and 97.8% (95% CI [94.7-99.1%]), respectively. The appendix was visualized in 243 cases (66.8%). Imaging confirmed alternative diagnoses in 75 patients, including most commonly colitis, enteritis or terminal ileitis (n = 25, 6.9%), adnexal cysts (n = 25, 6.9%) and mesenteric adenitis (n = 7, 1.9%). Contrast-enhanced MRI is capable of accurately diagnosing acute appendicitis while detecting many alternative entities of abdominal pain, and it allows good visualization of the appendix. Further evaluation is needed to determine whether contrast-enhanced MRI provides an advantage over non-enhanced MRI for imaging evaluation of acute abdominal pain in the pediatric population.

Differentiation of malignant and benign small peripheral pulmonary nodules using time-intensity curve on dynamic MRI

Along with the increase in regularly scheduled pulmonary check-ups, there has also been an increase in the detection of nodules smaller than 20 mm. The differentiation of benign or malignant nodules is reportedly facilitated by adding contrast-enhanced MRI to high-resolution CT. However, there are few studies on peripheral pulmonary nodules smaller than 20 mm. We examined the use of contrast-enhanced MRI for peripheral pulmonary nodules smaller than 20 mm that were difficult to differentiate between benign or malignant using high-resolution CT, and compared the results with the pathological views of the excised specimens. On the time-intensity curve in the dynamic study, we classified it as "steep type", "flat type", "gradual type", and "not visible". The result was low. As for 75% of sensitivity, 42.9% of specificity, 68.6% of accuracy. However, as for 85.7% of sensitivity, 100% of specificity, 86.7% of accuracy in nodules with less than more than 15mm and 20mm of greatest dimension. The differentiation of benign or malignant nodules smaller than 15 mm is difficult by dynamic MRI, but it appears that MRI facilitates the diagnosis of nodules larger than 15 mm.

Contrast enhancement by lipid-based MRI contrast agents in mouse atherosclerotic plaques; a longitudinal study

The use of contrast-enhanced MRI to enable in vivo specific characterization of atherosclerotic plaques is increasing. In this study the intrinsic ability of two differently sized gadolinium-based contrast agents to enhance atherosclerotic plaques in ApoE(-/-) mice was evaluated with MRI. We obtained a kinetic profile for contrast enhancement, as the literature data on optimal imaging time points is scarce, and assessed the longer-term kinetics. Signal enhancement in the wall of the aortic arch, following intravenous injection of paramagnetic micelles and liposomes, was followed for 1 week. In vivo T(1)-weighted MRI plaque enhancement characteristics were complemented by fluorescence microscopy of NIR(664) incorporated in the contrast agents and quantification of tissue and blood Gd-DTPA. Both micelles and liposomes enhanced contrast in T(1)-weighted MR images of plaques in the aortic arch. The average contrast-to-noise ratio increased after liposome or micelle injection to 260 or 280% respectively, at 24 h after injection, compared with a pre-scan. A second wave of maximum contrast enhancement was observed around 60-72 h after injection, which only slowly decreased towards the 1 week end-point. Confocal fluorescence microscopy and whole body fluorescence imaging confirmed MRI-findings of accumulation of micelles and liposomes. Plaque permeation of contrast agents was not strongly dependent on the contrast agent size in this mouse model. Our results show that intraplaque accumulation over time of both contrast agents leads to good plaque visualization for a long period. This inherent intraplaque accumulation might make it difficult to discriminate passive from targeted accumulation. This implies that, in the development of targeted contrast agents on a lipid-based backbone, extensive timing studies are required.

Imaging Characteristics of Cavernous Sinus Cavernous Hemangiomas

Cavernous hemangiomas occur rarely in the cavernous sinus and are difficult to diagnose preoperatively. The imaging of these lesions resembles other benign paracavernous lesions such as schwannomas and meningiomas. Profuse intraoperative bleeding may be encountered during surgical resection of these lesions. A preoperative diagnosis is therefore important to alert the surgeon. We report on the imaging characteristics of two different histopathological types of cavernous sinus cavernous hemangiomas and the use of contrast-enhanced MRI, diffusion-weighted MRI and magnetic resonance spectroscopy in the differential diagnosis of these lesions.

Role of O-(2-18F-Fluoroethyl)-l-Tyrosine PET for Differentiation of Local Recurrent Brain Metastasis from Radiation Necrosis

The aim of this study was to investigate the potential of O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) PET for differentiating local recurrent brain metastasis from radiation necrosis after radiation therapy because the use of contrast-enhanced MRI for this issue is often difficult. Thirty-one patients (mean age ± SD, 53 ± 11 y) with single or multiple contrast-enhancing brain lesions (n = 40) on MRI after radiation therapy of brain metastases were investigated with dynamic (18)F-FET PET. Maximum and mean tumor-to-brain ratios (TBR(max) and TBR(mean), respectively; 20-40 min after injection) of (18)F-FET uptake were determined. Time-activity curves were generated, and the time to peak (TTP) was calculated. Furthermore, time-activity curves of each lesion were assigned to one of the following curve patterns: (I) constantly increasing (18)F-FET uptake, (II) (18)F-FET uptake peaking early (TTP ≤ 20 min) followed by a plateau, and (III) (18)F-FET uptake peaking early (TTP ≤ 20 min) followed by a constant descent. The diagnostic accuracy of the TBR(max) and TBR(mean) of (18)F-FET uptake and the curve patterns for the correct identification of recurrent brain metastasis were evaluated by receiver-operating-characteristic analyses or Fisher exact test for 2 × 2 contingency tables using subsequent histologic analysis (11 lesions in 11 patients) or clinical course and MRI findings (29 lesions in 20 patients) as reference. Both TBR(max) and TBR(mean) were significantly higher in patients with recurrent metastasis (n = 19) than in patients with radiation necrosis (n = 21) (TBR(max), 3.2 ± 0.9 vs. 2.3 ± 0.5, P < 0.001; TBR(mean), 2.1 ± 0.4 vs. 1.8 ± 0.2, P < 0.001). The diagnostic accuracy of (18)F-FET PET for the correct identification of recurrent brain metastases reached 78% using TBR(max) (area under the ROC curve [AUC], 0.822 ± 0.07; sensitivity, 79%; specificity, 76%; cutoff, 2.55; P = 0.001), 83% using TBR(mean) (AUC, 0.851 ± 0.07; sensitivity, 74%; specificity, 90%; cutoff, 1.95; P < 0.001), and 92% for curve patterns II and III versus curve pattern I (sensitivity, 84%; specificity, 100%; P < 0.0001). The highest accuracy (93%) to diagnose local recurrent metastasis was obtained when both a TBR(mean) greater than 1.9 and curve pattern II or III were present (AUC, 0.959 ± 0.03; sensitivity, 95%; specificity, 91%; P < 0.001). Our findings suggest that the combined evaluation of the TBR(mean) of (18)F-FET uptake and the pattern of the time-activity curve can differentiate local brain metastasis recurrence from radionecrosis with high accuracy. (18)F-FET PET may thus contribute significantly to the management of patients with brain metastases.

The Incremental Value of Contrast-Enhanced MRI in the Detection of Biopsy-Proven Local Recurrence of Prostate Cancer After Radical Prostatectomy: Effect of Reader Experience

The purpose of this study is to retrospectively assess the incremental value of contrast-enhanced MRI (CE-MRI) to T2-weighted MRI in the detection of postsurgical local recurrence of prostate cancer by readers of different experience levels, using biopsy as the reference standard. Fifty-two men with biochemical recurrence after prostatectomy underwent 1.5-T endorectal MRI with multiphase contrast-enhanced imaging and had biopsy within 3 months of MRI. Two radiologists (reader 1 had 1 year and reader 2 had 6 years of experience) independently reviewed each MRI study and classified the likelihood of recurrent cancer on a 5-point scale. Areas under receiver operating characteristic curves (A(z)) were calculated to assess readers' diagnostic performance with T2-weighted MRI alone and combined with CE-MRI. Interobserver agreement was assessed using Cohen kappa statistics. Thirty-three patients (63%) had biopsy-proven local recurrence of prostate cancer. With the addition of CE-MRI to T2-weighted imaging, the A(z) for cancer detection increased significantly for reader 1 (0.77 vs 0.85; p = 0.0435) but not for reader 2 (0.86 vs 0.88; p = 0.7294). The use of CE-MRI improved interobserver agreement from fair (κ = 0.39) to moderate (κ = 0.58). CE-MRI increased interobserver agreement and offered incremental value to T2-weighted MRI in the detection of locally recurrent prostate cancer for the relatively inexperienced reader.

Avascular necrosis (AVN) of the proximal fragment in scaphoid nonunion: Is intravenous contrast agent necessary in MRI?

Purpose The purpose of this prospective study is to assess the diagnostic value of intravenously applied contrast agent for diagnosing osteonecrosis of the proximal fragment in scaphoid nonunion, and to compare the imaging results with intraoperative findings. Materials and methods In 88 patients (7 women, 81 men) suffering from symptomatic scaphoid nonunion, preoperative MRI was performed (coronal PD-w FSE fs, sagittal-oblique T1-w SE nonenhanced and T1-w SE fs contrast-enhanced, sagittal T2*-w GRE). MRI interpretation was based on the intensity of contrast enhancement: 0 = none, 1 = focal, 2 = diffuse. Intraoperatively, the osseous viability was scored by means of bleeding points on the osteotomy site of the proximal scaphoid fragment: 0 = absent, 1 = moderate, 2 = good. Results Intraoperatively, 17 necrotic, 29 compromised, and 42 normal proximal fragments were found. In nonenhanced MRI, bone viability was judged necrotic in 1 patient, compromised in 20 patients, and unaffected in 67 patients. Contrast-enhanced MRI revealed 14 necrotic, 21 compromised, and 53 normal proximal fragments. Judging surgical findings as the standard of reference, statistical analysis for nonenhanced MRI was: sensitivity 6.3%, specificity 100%, positive PV 100%, negative PV 82.6%, and accuracy 82.9%; statistics for contrast-enhanced MRI was: sensitivity 76.5%, specificity 98.6%, positive PV 92.9%, negative PV 94.6%, and accuracy 94.3%. Sensitivity for detecting avascular proximal fragments was significantly better ( p < 0.001) in contrast-enhanced MRI in comparison to nonenhanced MRI. Conclusion Viability of the proximal fragment in scaphoid nonunion can be significantly better assessed with the use of contrast-enhanced MRI as compared to nonenhanced MRI. Bone marrow edema is an inferior indicator of osteonecrosis. Application of intravenous gadolinium is recommended for imaging scaphoid nonunion.

Contrast enhancement by differently sized paramagnetic MRI contrast agents in mice with two phenotypes of atherosclerotic plaque

Interest in the use of contrast-enhanced MRI to enable in vivo specific characterization of atherosclerotic plaques is increasing. In this study the intrinsic ability of three differently sized gadolinium-based contrast agents to permeate different mouse plaque phenotypes was evaluated with MRI. A tapered cast was implanted around the right carotid artery of apoE(-/-) mice to induce two different plaque phenotypes: a thin cap fibroatheroma (TCFA) and a non-TCFA lesion. Both plaques were allowed to develop over 6 and 9 weeks, leading to an intermediate and advanced lesion, respectively. Signal enhancement in the carotid artery wall, following intravenous injection of Gd-HP-DO3A as well as paramagnetic micelles and liposomes was evaluated. In vivo T(1) -weighted MRI plaque enhancement characteristics were complemented by fluorescence microscopy and correlated to lesion phenotype. The two smallest contrast agents, i.e. Gd-HP-DO3A and micelles, were found to enhance contrast in T(1) -weighted MR images of all investigated plaque phenotypes. Maximum contrast enhancement ranged between 53 and 70% at 6 min after injection of Gd-HP-DO3A with highest enhancement and longest retention in the non-TCFA lesion. Twenty-four hours after injection of micelles maximum contrast enhancement ranged between 24 and 35% in all plaque phenotypes. Administration of the larger liposomes did not cause significant contrast enhancement in the atherosclerotic plaques. Confocal fluorescence microscopy confirmed the MRI-based differences in plaque permeation between micelles and liposomes. Plaque permeation of contrast agents was strongly dependent on size. Our results implicate that, when equipped with targeting ligands, liposomes are most suitable for the imaging of plaque-associated endothelial markers due to low background enhancement, whereas micelles, which accumulate extravascularly on a long timescale, are suited for imaging of less abundant markers inside plaques. Low molecular weight compounds may be employed for target-specific imaging of highly abundant extravascular plaque-associated targets.

Myocardial scar as arrhythmia risk in patients with hypertrophic cardiomyopathy

To provide an overview of the potential use of contrast-enhanced MRI as tool for further risk stratification in patients with hypertrophic cardiomyopathy (HCM). The presence of scar measured by contrast-enhanced MRI has been shown to predict poor prognosis in several models of cardiomyopathy, including ischemic and nonischemic dilated cardiomyopathy. Current strategy to identify HCM patients who are at increased risk for sudden cardiac death is still not ideal. Recent data suggest that the presence of scar measured by contrast-enhanced MRI is a predictor of arrhythmias and poor prognosis in patients with HCM. MRI is a potential technique to help identify HCM patients who are at risk for sudden cardiac death.

MRI in the diagnosis of incomplete testicular torsion

We present a case of subacute left testicular pain and enlargement. Scrotal Doppler ultrasound revealed an enlarged left testicle with symmetrical intra-testicular colour flow bilaterally. Contrast-enhanced MRI demonstrated incomplete testicular torsion which was verified at surgery. To our knowledge, this is the first report on the use of contrast-enhanced MRI in the diagnosis of incomplete testicular torsion.

Diagnosis of Osteomyelitis in Children: Utility of Fat-Suppressed Contrast-Enhanced MRI

The purpose of this study was to determine whether the use of fat-suppressed contrast-enhanced MRI, compared with unenhanced MRI alone, increases reader confidence in the diagnosis of osteomyelitis and its complications in children. MRI studies of 78 skeletally immature children and adolescents (median age, 3.6 years) with suspected nonspinal osteomyelitis were reviewed in consensus by two readers. Unenhanced images were evaluated first and then contrast-enhanced MR images. Images were scored for the presence or absence of osteomyelitis, abscess, septic arthritis, and physeal involvement on a 5-point scale ranging from definitely absent to definitely present. Forty-two additional studies were evaluated to test interobserver agreement. Osteomyelitis was clinically diagnosed in 40 cases (51%). There was no significant difference between the sensitivity and specificity of unenhanced MRI (p = 1.0) and those of contrast-enhanced MRI (p = 0.77) for the diagnosis of osteomyelitis. Nonetheless, there was a significant (p < 0.001) increase in confidence in the diagnosis of osteomyelitis and its complications. This increase in confidence was most pronounced for the diagnosis of abscess (46%). The addition of contrast enhancement was least useful in findings deemed definitely absent on unenhanced MR images. Although it does not increase the sensitivity or specificity of the diagnosis, use of contrast-enhanced MRI does increase reader confidence in the diagnosis of osteomyelitis and its complications in cases in which bone or soft-tissue edema is found on unenhanced images. In the clear absence of edema on unenhanced images, however, contrast enhancement is not needed.

Maximum intensity projection as a tool to diagnose early rheumatoid arthritis

In this study, we investigated the usefulness of contrast-enhanced MRI with maximum intensity projection (MIP) as a convenient tool for detecting early rheumatoid arthritis (RA). A total of 21 patients with undiagnosed arthritis of the hands at the initial visit were enrolled in a prospective study over a 1-year period. The number of swollen joints found during physical examination at this first visit, the results of serological tests and the number of synovitis joints diagnosed on MIP images were compared between the RA group and non-RA group. Of the 21 patients, 17 (81%) from the initial study who were followed up for an additional 1 year entered this study. Of these, 5 met the conditions for diagnosis of RA during follow-up, and 12 did not. MIP images were used to review the arthritis of RA patients, and a significant difference was found in the number of synovitis inflammations detected with MIP images when compared with findings after physical examinations. The two criteria of positive CARF and/or anti-CCP antibody and symmetrical synovitis in bilateral hands on MIP images allowed the prediction of RA with 100% sensitivity and 75% specificity. Thus, MIP is a useful tool for making early diagnosis of RA because it yields clear visualization even with just one image.