Diffusion Weighted Imaging in Spine Tumors.

Diffusion weighted imaging (DWI) has developed into a powerful tool for the evaluation of spine tumors, particularly for the assessment of vertebral marrow lesions and intramedullary tumors. Advances in magnetic resonance techniques have improved the quality of spine DWI and diffusion tensor imaging (DTI) in recent years, with increased reproducibility and utilization. DTI, with quantitative parameters such as fractional anisotropy and qualitative visual assessment of nerve fiber tracts, can play a valuable role in the evaluation and surgical planning of spinal cord tumors. These widely available techniques can be used to enhance the diagnostic evaluation of spinal tumors.

Trans-synaptic degeneration of the optic radiation from optic nerve atrophy.

Fourty-seven-year-old woman with 5-year history of progressive decreased left eye vision. Optical coherence tomography showed optic nerve atrophy (left > right) and brain MRI revealed T2 hyperintense signal along the course of left optic radiations. We present a case of a trans-synaptic degeneration of the optic radiation in a patient with confirmed optic atrophy. Trans-synaptic degeneration of the optic radiation without associated infarct or inflammatory disease has not been reported before in patients with optic atrophy.

Prospective Motion Correction for Brain MRI Using an External Tracking System.

BACKGROUND AND PURPOSE: A wide range of strategies have been developed to mitigate motion, as a major source of image quality degradation in clinical MRI. We aimed to assess the efficiency of a commercially available prospective motion correction (PMC) system in reducing motion in acquiring high-resolution 3D magnetization-prepared rapid gradient-echo (MPRAGE). METHODS: A total of 100 patients who referred for brain MRI studies were prospectively imaged using a 3.0T scanner. 3D MPRAGE acquisition was obtained with and without application of PMC. The motion tracking system (KinetiCor Inc.) consisted of a quad camera apparatus, which tracks a specific marker on patient's head by evaluating the marker's optical pattern. The patient's head motion in 6 degrees of freedom throughout the acquisition was then incorporated into the MRI sequence, updating the image acquisition in real time based on the most recent head pose data. MPRAGE images with and without motion correction were assessed independently by two board-certified neuroradiologists using a 5-point Likert scale. Statistical analysis included kappa and Wilcoxon Rank-Sum tests. RESULTS: Observers 1 and 2 identified nondiagnostic studies in 17.2% and 20.7% of patients (K = .78, 95% CI .70-.86) without motion correction and in 5.7% and 8% of the studies with motion correction (K = .84, 95% CI .76-.92). The number of nondiagnostic studies was significantly (P = .001) reduced from 19.5% to 5.7% after motion correction in consensus read analysis. CONCLUSION: The described motion tracking system can be used effectively in clinical practice reducing motion artifact and improving image quality of 3D MPRAGE sequence.

CLINICALLY SILENT ADRENOCORTICOTROPIC HORMONE-SECRETING CROOKE CELL ADENOMA PRESENTING AS UNILATERAL EAR PAIN.

OBJECTIVE: Crooke cell adenoma (CCA) is a rare tumor of the anterior pituitary. It is highly aggressive and carries significant risk of morbidity and mortality. METHODS: This report focuses on the presentation of this disease process and review diagnosis and treatment. The patient is a 64-year-old male with a history of resected pituitary adenoma of unknown pathology. RESULTS: The patient underwent serial magnetic resonance imaging surveillance for numerous years without recurrence of tumor, however eventually developed symptoms of worsening left ear pain over 3 weeks that rapidly evolved to include ptosis. Imaging revealed a new pituitary macroadenoma. Urgent surgical resection revealed histopathological diagnosis of CCA. Corticotroph adenomas represent a rare subset of pituitary tumors. Clinically silent pituitary tumors demonstrate relatively higher rates of cavernous sinus invasion (30% versus 18%) and progression or recurrence (34% versus 6%) when compared to nonfunctioning adenomas. In CCA, only 65% of patients have clinical features of Cushing disease at presentation. Twenty-four-hour urinary free cortisol is discussed in the literature as a potential tool, where a value 4 times the upper limit of normal was predictive of higher risk of having Crooke cell changes. With a recurrence rate of up to 60%, multimodal treatment (surgery and radiation) is preferred. CONCLUSION: This case highlights early detection and treatment as keys to reducing the risk of morbidity and mortality from CCA. Currently, there are limited tools for identifying patients who are high risk for developing Crooke cell changes. Treatment modalities classically include surgery and radiotherapy. Adjuvant and novel chemotherapies are being explored.

Quantification of perivascular spaces at 7T: A potential MRI biomarker for epilepsy.

PURPOSE: 7T (7T) magnetic resonance imaging (MRI) facilitates the visualization of the brain with resolution and contrast beyond what is available at conventional clinical field strengths, enabling improved detection and quantification of small structural features such as perivascular spaces (PVSs). The distribution of PVSs, detected in vivo at 7T, may act as a biomarker for the effects of epilepsy. In this work, we systematically quantify the PVSs in the brains of epilepsy patients and compare them to healthy controls. METHODS: T2-weighted turbo spin echo images were obtained at 7T on 21 epilepsy patients and 17 healthy controls. For all subjects, PVSs were manually marked on Osirix image analysis software. Marked PVSs with diameter≥0.5mm were then mapped by hemisphere and lobe. The asymmetry index (AI) was calculated for each region and the maximum asymmetry index (|AImax|) was reported for each subject. The asymmetry in epilepsy subjects was compared to that of controls, and the region with highest asymmetry was compared to the suspected seizure onset zone. RESULTS: There was a significant difference between the |AImax| in epilepsy subjects and in controls (p=0.016). In 72% of patients, the region or lobe of the brain showing maximum PVS asymmetry was the same as the region containing the suspected seizure onset zone. CONCLUSION: These findings suggest that epilepsy may be associated with significantly asymmetric distribution of PVSs in the brain. Furthermore, the region of maximal asymmetry of the PVSs may help provide localization or confirmation of the seizure onset zone.

First Application of 7-T Magnetic Resonance Imaging in Endoscopic Endonasal Surgery of Skull Base Tumors.

BACKGROUND: Successful endoscopic endonasal surgery for the resection of skull base tumors is reliant on preoperative imaging to delineate pathology from the surrounding anatomy. The increased signal-to-noise ratio afforded by 7-T MRI can be used to increase spatial and contrast resolution, which may lend itself to improved imaging of the skull base. In this study, we apply a 7-T imaging protocol to patients with skull base tumors and compare the images with clinical standard of care. METHODS: Images were acquired at 7 T on 11 patients with skull base lesions. Two neuroradiologists evaluated clinical 1.5-, 3-, and 7-T scans for detection of intracavernous cranial nerves and internal carotid artery (ICA) branches. Detection rates were compared. Images were used for surgical planning and uploaded to a neuronavigation platform and used to guide surgery. RESULTS: Image analysis yielded improved detection rates of cranial nerves and ICA branches at 7 T. The 7-T images were successfully incorporated into preoperative planning and intraoperative neuronavigation. CONCLUSIONS: Our study represents the first application of 7-T MRI to the full neurosurgical workflow for endoscopic endonasal surgery. We detected higher rates of cranial nerves and ICA branches at 7-T MRI compared with 3- and 1.5-T MRI, and found that integration of 7 T into surgical planning and guidance was feasible. These results suggest a potential for 7-T MRI to reduce surgical complications. Future studies comparing standardized 7-, 3-, and 1.5-T MRI protocols in a larger number of patients are warranted to determine the relative benefit of 7-T MRI for endonasal endoscopic surgical efficacy.

Imaging of Spinal Manifestations of Hematological Disorders.

Imaging manifestations of hematological diseases and their potential complications are broad, and there may be significant overlap in features of various disease processes. Knowledge of appropriate choice of imaging test, pertinent imaging patterns, and pathophysiology of disease can help the reader increase specificity in the diagnosis and treatment of the patient. Most importantly, we encourage readers of this review to engage their radiologists during the diagnostic, treatment, and management phases of care delivery.

Contrast-Enhanced Dixon Fat-Water Separation Imaging of the Spine: Added Value of Fat, In-Phase and Opposed-Phase Imaging in Marrow Lesion Detection.

OBJECTIVE: Beyond fat suppression (FS), the efficacy of (fat-water separation or Dixon [FWD]) Dixon imaging in gadolinium-enhanced spine imaging has yet to be validated. This study evaluated enhanced opposed-phase (OP) and fat-only (FO) images along with water-only (WO; FS) images against traditional unenhanced techniques and rated the incremental value of in-phase imaging in patients with presumed neoplastic focal spine lesions. METHODS: A retrospective cohort study of 36 subjects with focal spine lesions imaged with FWD was evaluated qualitatively and quantitatively. RESULTS: Enhanced OP, WO, and FO images were of significant value in detection of osseous lesions, surpassing the lesion conspicuity with conventional techniques both qualitatively and quantitatively, although the impact of in-phase imaging was limited. Water-only imaging performed well for FS. CONCLUSIONS: Contrast-enhanced FO, WO, and OP outperform traditional techniques, providing reliable lesion characterization and highest conspicuity. In-phase imaging offered limited impact on the subjective assessment of enhancement. The added value and robustness of FWD, particularly the unique contrast provided by FO imaging, suggests consideration for routine use for postgadolinium spine imaging.

Three-Tesla imaging of the pituitary and parasellar region: T1-weighted 3-dimensional fast spin echo cube outperforms conventional 2-dimensional magnetic resonance imaging.

OBJECTIVE: We explored how a novel T1-weighted 3-dimensional (3D) fast spin echo (FSE) sequence (Cube; GE, Waukesha, Wis) might outperform conventional 2-dimensional (2D) FSE techniques for contrast-enhanced imaging of the pituitary and parasellar region. METHODS: Ninety-one patients were imaged with 3D Cube and conventional 2D FSE on a 3.0-T magnetic resonance scanner. Two neuroradiologists independently assessed images for anatomical delineation (infundibulum, optic apparatus, and cavernous sinus), degree of artifact, and confidence in lesion definition or exclusion using a 5-point scale. In addition, the readers were asked to rank overall preference. RESULTS: Readers A and B found 3D Cube to be better or equal to 2D FSE in 84% and 86% of the cases. Three-dimensional Cube provided significantly better images than 2D FSE with respect to delineation of the infundibulum (P < 0.0001), cavernous sinus (P < 0.0001), optic apparatus (P = 0.002 for reader A and P = 0.265 for reader B), and fewer artifacts at the sellar floor (P < 0.0001). Three-dimensional Cube provided greater lesion conspicuity or confidence in lesion exclusion (P < 0.0001). CONCLUSIONS: Three-dimensional Cube provides superior quality with thinner slices as well as diminished artifact and can replace conventional 2D FSE sequences for routine evaluations of the pituitary and parasellar region.

Recurrent temporal bone tenosynovial giant cell tumor with chondroid metaplasia: the use of imaging to assess recurrence.

Tenosynovial giant cell tumor (TGCT) is a benign proliferative lesion of unclear etiology. It is predominantly monoarticular and involves the synovium of the joint, tendon sheath, and bursa. TGCT of the temporomandibular joint (TMJ) is rare and aggressive resulting in destruction of surrounding structures. The diagnosis may be suggested by imaging, mainly by the MR features and PET/CT, and confirmed by histopathology. We describe the case of a 50-year-old man who presented with right-sided hearing loss, tinnitus and TMJ pain. Pathology revealed tenosynovial giant cell tumor with chondroid metaplasia. Six years later he developed a recurrence, which was documented to our knowledge for the first time with CT, MR and FDG PET/CT imaging.

Comparison of radiation exposure and cost between dynamic computed tomography and sestamibi scintigraphy for preoperative localization of parathyroid lesions.

IMPORTANCE: Dynamic computed tomography (CT) is emerging as a first-line alternative to sestamibi scintigraphy for preoperative localization of parathyroid lesions. In recent years, there has been increased concern over the impact of radiation exposure from medical imaging, as well as on the cost of diagnostic medical procedures. An ideal diagnostic procedure would be cost effective while minimizing hazardous exposures and complication rates. OBJECTIVE: To compare the radiation dose and financial cost of dynamic CT with sestamibi scintigraphy. DESIGN, SETTING, AND PATIENTS: A retrospective review of 263 patients at a large, urban, tertiary referral center who underwent either dynamic parathyroid CT or sestamibi scintigraphy for any etiology of hyperparathyroidism from 2006 through 2010. MAIN OUTCOMES AND MEASURES: The 2 primary study outcomes were radiation exposure measured in millisieverts (mSv) and medical charges for the respective diagnostic procedures. The study was conducted with the hypothesis that dynamic parathyroid CT would have slightly greater radiation exposure with similar cost to sestamibi scintigraphy. RESULTS: Dynamic parathyroid CT and sestamibi scintigraphy delivered mean radiation doses of 5.56 and 3.33 mSv, respectively (P < .05). Charges totaled $1296 for thin-cut dynamic parathyroid CT and a mean of $1112 for sestamibi scintigraphy, depending on the type and amount of radiotracer injected. Although multiphase CT scanning took less than 5 minutes, sestamibi scintigraphy lasted a mean time of 306 minutes. A total of 62 of 119 patients (52%) in the CT group have undergone operative treatment to date, whereas all patients in the sestamibi arm underwent operative treatment of their hyperparathyroidism. Of the patients who underwent a surgical procedure, CT correctly identified the side of the parathyroid adenoma in 54 of 62 patients (87%), while sestamibi scintigraphy only correctly lateralized 90 of 122 adenomas (74%) as confirmed by exploratory surgery, intraoperative parathyroid hormone levels, and pathologic features. A dynamic parathyroid CT correctly predicted multiglandular disease in 1 of 7 patients (14%), while sestamibi scintigraphy correctly predicted multiglandular disease in 8 of 23 patients (35%). CONCLUSIONS AND RELEVANCE: In patients who underwent directed parathyroid surgery, dynamic CT is comparable to sestamibi scintigraphy in patients with hyperparathyroidism. Although CT delivers a higher dose of radiation, the average background radiation exposure in the United States is 3 mSv/y, and added exposures of less than 15 mSv are considered low risk for carcinogenesis. Overall, dynamic parathyroid CT is a safe, cost-effective alternative to sestamibi scintigraphy.