Artifacts in Breast Magnetic Resonance Imaging.

As breast magnetic resonance imaging has evolved to become a routine part of clinical practice, so too has the need for radiologists to be aware of its potential pitfalls and limitations. Unique challenges arise in the identification and remedy of artifacts in breast magnetic resonance imaging, and it is important that radiologists and technicians work together to optimize protocols and monitor examinations such that these may be minimized or avoided entirely. This article presents patient-related and technical artifacts that may give rise to reduced image quality and ways to recognize and reduce them.

Ultrashort time-to-echo MRI of the cartilaginous endplate: technique and association with intervertebral disc degeneration.

INTRODUCTION: The purpose of this study was to report the feasibility of the ultrashort time-to-echo (UTE) MRI technique to assess cartilaginous endplate (CEP) defects in humans in vivo and to assess their relationship with intervertebral disc (IVD) degeneration. METHODS: Nine volunteer subjects (mean age = 43.9 years; range = 22-61 years) were recruited, representing 54 IVDs and 108 CEPs. The subjects underwent T2-weighted and UTE MRI to assess for the presence and severity of IVD degeneration, and for the presence of CEP defects, respectively, from T12 to S1. IVD degeneration was graded according to the Schneiderman et al. classification on T2-weighted MRI. CEP defects were defined on UTE MRI as discontinuity of high signal over four consecutive images and were independently assessed by two observers. RESULTS: Thirty-seven out of 108 (34.3%) CEPs had defects, which mainly occurred at T12/L1, L1/L2 and L4/L5 (P = 0.008). Multivariate logistic regression revealed that lower body mass index (P = 0.009) and younger (P = 0.034) individuals had a decreased likelihood of having CEP defects. A statistically significant association was found to exist between the presence of CEP defects and IVD degeneration (P = 0.036). A higher prevalence of degenerated IVDs with CEP defects was found at L4/5 and L5/S1, while degenerated IVDs with no CEP defects were found throughout the whole lumbar region. Mean IVD degeneration scores of the L4/5 and L5/S1 levels with CEP defects were higher in comparison with those with no CEP defects. CONCLUSIONS: Our study demonstrates the feasibility of using UTE MRI in humans in vivo to assess the integrity of the CEP. A statistically significant association was found to exist between the presence of CEP defects and IVD degeneration. In the lower lumbar region, more severe degeneration was found to occur in the IVDs with CEP defects than in those without defects.

Radiation-induced sarcoma in spine.

Although radiotherapy is a part of treatment in cancers, it can also induce malignancy as a late complication. The presence of radiation-induced sarcomas in bone, although not very common, is acknowledged. The onset of radiation-induced sarcoma in the spine however, is not well recognized. We present here a case of radiation-induced fibrosarcoma in the T1 lamina and spinous process in a patient with a history of breast cancer treated with radiotherapy 30 years prior.

18F-FDG PET/CT diagnosis of vagus nerve neurolymphomatosis.

A 62-year-old woman was in remission from previously treated stage IV diffuse large B-cell lymphoma with cranial involvement. She presented with new-onset hoarseness of voice and choking; MRI of the brain showed disease recurrence in the left cavernous sinus. She was subsequently referred for F-FDG PET/CT with contrast for further evaluation of lymphomatous recurrence. F-FDG PET/CT not only revealed hypermetabolic activity in the left cavernous sinus correlating to the MRI findings but also showed an interesting manifestation explaining the patient's hoarseness of voice, being neurolymphomatosis along the left vagus nerve.

Hepatic radiation injury in distal esophageal carcinoma: a case report.

The liver is an organ at particular risk for toxicity after radiotherapy for distal esophageal cancer. We report the case of a 58-year-old man with distal esophageal carcinoma, who underwent follow-up FDG-PET/CT 6 weeks after completion of preoperative neoadjuvant chemoradiotherapy. The left hepatic lobe and caudate showed new, round areas of hypoenhancement on CECT and increased FDG-uptake, which resembled metastases. However an, as yet unreported, linear configuration of FDG uptake was noted and found to correlate with the anterior posterior-posterior anterior opposing field radiotherapy portal.

Utility of FDG PET/CT in the assessment of myeloid sarcoma.

OBJECTIVE: Myeloid sarcoma (MS) is a rare extramedullary manifestation of acute myeloid leukemia that often presents during remission or disease relapse. With awareness of this clinical entity and the appropriate clinical history, MS can be detected despite its nonspecific radiologic features. CONCLUSION: This article highlights the utility of (18)F-FDG PET/CT, which has high sensitivity in detecting early MS and provides a systemic overview of tumor burden, and its potential role in monitoring of treatment response.

The use of FDG-PET/CT in extranodal Rosai-Dorfman disease of bone.

We report the case of a 41-year-old man with extranodal Rosai-Dorfman disease (RDD), presenting with clinically detectable bone involvement only. The use of FDG-PET/CT in the diagnosis of RDD is discussed.

Correlation of measurements from diffusion weighted MR imaging and FDG PET/CT in GIST patients: ADC versus SUV.

PURPOSE: We investigated the correlation relationship between ADCs measured by MRI and SUVs measured by PET/CT of lesions on GIST (gastrointestinal stromal tumor) patients to verify if MR is able to replace or serve as an alternative to PET/CT in GIST staging and treatment monitoring. MATERIALS AND METHODS: Between September 2010 and January 2011, five patients with histologically proven metastatic GIST in Queen Mary Hospital, Hong Kong were enrolled into our study. All patients underwent both MRI and PET/CT scans at prognosis. Pearson's correlations of twenty-nine lesions were conducted between 5 pairs of ADCs and SUVs values. RESULTS: Lesions in the liver, peritoneum or bowel loops were found by PET/CT and no extra-abdominal lesion was identified. All twenty-nine lesions are identifiable by MRI with sensitivity of 100%. Significant inverse correlation were found between ADC(mean) and SUV(mean) (P=0.006), ADC(mean) and SUV(max) (P=0.010), ADC(min) and SUV(max) (P=0.014), ADC(min) and SUV(mean) (P=0.026), rADC(min) and rSUV(max) (P=0.047). CONCLUSION: DWI is comparable to PET/CT in visually detecting the GIST lesions' location. Significant inverse correlations were found between ADCs from DWIBS and SUVs from PET/CT on data of GIST patients. This finding demonstrates that DWI is potentially capable of offering similar information for diagnosis and treatment response evaluating in GIST's patients as PET/CT does. Furthermore, ADC(min), which is determined by single pixel, is not as reliable as ADC(mean), which is weighted average value of the whole lesion volume.

Age-related diffusion patterns in human lumbar intervertebral discs: a pilot study in asymptomatic subjects.

Diffusion tensor imaging (DTI) may provide an accurate noninvasive method of detecting degenerative matrix alterations in human lumbar intervertebral discs (IVDs). This study aimed to investigate age-related degenerative changes in human lumbar IVDs using DTI. Thirty asymptomatic volunteers ranging in age from 25 to 67 years underwent single-shot diffusion weighted echo-planar imaging on a 3 T scanner. DTI-derived metrics including fractional anisotropy (FA) and mean diffusivity (MD) were analyzed by a histogram analysis method. A Mann-Whitney test was used to compare subject groups (young and elderly) with respect to the diffusion measures, and piecewise linear regression was used to characterize the change in each metric as a function of age. We found significant age-related changes in the elderly adult group, with decrease of MD (11%, P<.001) and increase of FA (20%, P<.001). Our results demonstrate that the degenerative-related changes taking place in the IVDs through aging can be quantitatively accessed by DTI-derived metrics, while the morphologic changes are difficult to be identified in conventional T(2)-weighted images. Our initial findings suggest that it would be worthwhile to validate the relationship between DTI metrics and the actual degenerative status of IVDs using extracted disc samples and to extend it to studies on patients with degenerative discs in order to further explore the clinical usefulness and relevance of DTI.

Quantitative assessment of the cervical spinal cord damage in neuromyelitis optica using diffusion tensor imaging at 3 Tesla.

PURPOSE: To investigate whether quantitative MRI measures of cervical spinal cord white matter (WM) using diffusion tensor imaging (DTI) in neuromyelitis optica (NMO) differed from controls and correlated with clinical disability. MATERIALS AND METHODS: Ten referred patients and 12 healthy volunteers were imaged on a 3 Tesla scanner and patients were clinically assessed on the Expanded Disability Status Scale (EDSS). Two raters quantified DTI-derived indices from all participants, including fractional anisotropy (FA), mean diffusivity (MD), parallel diffusivity (lambda[parallel]) and perpendicular diffusivity (lambda[perpendicular]) at C1-C6 for lateral and dorsal columns. After the inter-rater reliability test, univariate correlations between DTI measures and disability were assessed using the Spearman's rho correlation coefficient. Multiple regression analysis was performed to investigate which DTI measures independently correlated with the clinical score. RESULTS: Statistical test results indicated high reliability of all DTI measurements between two raters. NMO patients showed reduced FA, increased MD and lambda[perpendicular] compared with controls while lambda[parallel] did not show any significant difference. The former three DTI metrics also showed significant correlations with disability scores, and especially FA was found to be sensitive to mild NMO (EDSS ≤ 3) CONCLUSION: FA is a potentially useful quantitative biomarker of otherwise normal appearing WM damage in NMO. Such damage is associated with clinical disability.

Assessment of glycosaminoglycan distribution in human lumbar intervertebral discs using chemical exchange saturation transfer at 3 T: feasibility and initial experience.

Recent studies have proposed that glycosaminoglycan chemical exchange saturation transfer (gagCEST) is associated with a loss of glycosaminoglycans (GAGs), which may be an initiating factor in intervertebral disc (IVD) degeneration. Despite its promising potential, this application has not been reported in human in vivo IVD studies because of the challenges of B(0) magnetic field inhomogeneity in gagCEST. This study aimed to evaluate the feasibility of quantifying CEST values in IVDs of healthy volunteers using a clinical 3 T scanner. A single-slice turbo spin echo sequence was used to quantify the CEST effect in various GAG phantoms and in IVDs of 12 volunteers. The phantom results indicated high correlation between gagCEST and GAG concentrations (R(2) = 0.95). With optimal B(0) inhomogeneity correction, in vivo CEST maps of IVDs showed robust contrast between the nucleus pulposus (NP) and the annulus fibrosus (AF) (p < 0.01), as well as higher signal in the central relative to the peripheral NP. In addition, a trend of decreasing CEST values from upper to lower disc levels was evident in NP. Our results demonstrate that in vivo gagCEST quantification in human lumbar IVDs is feasible at 3 T in combination with successful B(0) inhomogeneity correction, but without significant hardware modifications. Our initial findings suggest that it would be worthwhile to perform direct correlation studies between CEST and GAGs using cadaver samples, and to extend this novel technique to studies on patients with degenerative discs to better understand its distinct imaging features relative to conventional techniques.

Spectrum of (18)F-FDG PET/CT appearances in peritoneal disease.

OBJECTIVE: The objective of our study was to illustrate the spectrum of appearances of peritoneal diseases on (18)F-FDG PET/CT, show the usefulness of fused FDG PET/CT as a diagnostic tool for the peritoneum, and discuss the pitfalls in FDG PET/CT interpretation of peritoneal disease. CONCLUSION: Malignant and benign diseases may have peritoneal involvement, which can manifest as various imaging patterns on FDG PET/CT. Awareness of these patterns and of potential interpretation issues is important to optimize diagnostic accuracy.