Editor’s Choices

Usefulness of Pseudocontinuous Arterial Spin-Labeling for the Assessment of Patients with Head and Neck Squamous Cell Carcinoma by Measuring Tumor Blood Flow in the Pretreatment and Early Treatment Period

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Forty-one patients with head and neck squamous cell carcinoma were evaluated by using pseudocontinuous ASL. Quantitative tumor blood flow was calculated at the pretreatment and the early treatment periods. Pretreatment tumor blood flow in patients in the treatment failure group was significantly lower than that in patients in the local control group. The use of the percentage change of tumor blood flow combined with the percentage change of tumor volume had high diagnostic accuracy for predicting local control.

Abstract

BACKGROUND AND PURPOSE

For the assessment of the treatment response in non-surgical treatment, tumor blood flow provides the functional information of the tumor which is different from the morphological information such as tumor volume. The purpose of this study was to evaluate the diagnostic value of tumor blood flow values obtained by pseudocontinuous arterial spin-labeling in patients with head and neck squamous cell carcinoma.

MATERIALS AND METHODS

Forty-one patients with head and neck squamous cell carcinoma were evaluated by using pseudocontinuous arterial spin-labeling. Quantitative tumor blood flow was calculated at the pretreatment and the early treatment periods in all the patients, and the percentage change of tumor blood flow between the two was calculated. At the early treatment period, based on their tumor volume reduction rate, we divided the patients into stable disease and partial response groups for a subgroup analysis. The local control or failure was confirmed either by histopathology or by radiologic evaluation within the follow-up.

RESULTS

Pretreatment tumor blood flow in patients in the failure group was significantly lower than that in patients in the local control group. In the subgroup analysis of patients with stable disease, the percentage change of tumor blood flow was significantly larger (due to the tumor blood flow increase from pretreatment value) in the local control group than in

Multimodal Imaging in Malignant Brain Tumors: Enhancing the Preoperative Risk Evaluation for Motor Deficits with a Combined Hybrid MRI-PET and Navigated Transcranial Magnetic Stimulation Approach

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Patients with malignant brain tumors involving the central region underwent a hybrid O-(2-[18F]fluoroethyl)-L-tyrosine–PET-MR imaging and motor mapping by neuronavigated transcranial magnetic stimulation. The spatial relationship between functional tissue and lesion volumes as depicted by structural and metabolic imaging was analyzed. Tumor infiltration of the M1 region or the corticospinal tract as depicted by FET-PET is highly indicative of motor impairment, better than contrast-enhanced T1WI alone, and is of predictive value for operative-risk evaluation.

Abstract

BACKGROUND AND PURPOSE

Motor deficits in patients with brain tumors are caused mainly by irreversible infiltration of the motor network or by indirect mass effects; these deficits are potentially reversible on tumor removal. Here we used a novel multimodal imaging approach consisting of structural, functional, and metabolic neuroimaging to better distinguish these underlying causes in a preoperative setting and determine the predictive value of this approach.

MATERIALS AND METHODS

Thirty patients with malignant brain tumors involving the central region underwent a hybrid O-(2-[18F]fluoroethyl)-L-tyrosine–PET-MR imaging and motor mapping by neuronavigated transcranial magnetic stimulation. The functional maps served as localizers for DTI tractography of the corticospinal tract. The spatial relationship between functional tissue (motor cortex and corticospinal tract) and lesion volumes as depicted by structural and metabolic imaging was analyzed.

RESULTS

Motor impairment was found in nearly all patients in whom the contrast-enhanced T1WI or PET lesion overlapped functional tissue. All patients who functionally deteriorated after the operation showed such overlap on presurgical maps, while the absence of overlap predicted a favorable motor outcome. PET was superior to contrast-enhanced T1WI for revealing a motor deficit before the operation. However, the best correlation with clinical impairment was found for T2WI lesion overlap with functional tissue maps, but the prognostic value for motor recovery was not significant.

CONCLUSIONS

Overlapping contrast-enhanced T1WI or PET-positive signals

MR Angiographic–Guided Percutaneous Sclerotherapy for Venous Vascular Malformations: A Radiation Dose-Reduction Strategy

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This case series of 5 patients describes the authors’ approach to using dynamic MRA with direct puncture of venous malformations to define the angioarchitecture and draining veins in these lesions. MultiHance in a 1:100 dilution with normal saline solution was used for the contrast administration. Precontrast images were used as a mask and were digitally subtracted from the postcontrast images (13- and 51-second acquisitions, respectively). The authors conclude that they have developed a method to completely eliminate digital subtraction angiography x-ray radiation exposure during treatment of venous vascular malformations.

Summary

Click image to enlarge
Click image to enlarge

We present a new technique using MRA instead of the usual DSA to provide guidance in the treatment of venous vascular malformations. When one performs this embolization procedure, appropriate needle positioning within the malformation must be confirmed before injection of the sclerosing agent to prevent untoward complications. Time-resolved imaging of contrast kinetics–MRA can accurately depict the angioarchitecture of the lesion, which substantially reduces the total radiation dose in these patients who are commonly in the pediatric age group and usually require numerous treatment episodes.

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Spine Cryoablation: Pain Palliation and Local Tumor Control for Vertebral Metastases

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This is a retrospective study of imaging-guided spine cryoablation that was performed on 31 vertebral metastases in 14 patients. The lesions were refractory to conventional chemoradiation therapy or analgesics and were ablated to achieve pain palliation and local tumor control. The procedures were performed with the patient under conscious sedation (13 patients) or general anesthesia in 1 case. Postcryoablation MR imaging and PET/CT imaging were available for all patients. Spinal nerve and soft-tissue thermal protection techniques were implemented in all ablations (epidural or neuroforaminal carbon dioxide or warmed 5% dextrose). There were statistically significant decreases in the median numeric pain rating scale score and analgesic usage at 1-week, 1-month, and 3-month time points. Local tumor control was achieved in 96.7% (30/31) of tumors.

Abstract

Figure from Tomasian et al -- Editor's Choice
A 69-year-old man with metastatic follicular thyroid carcinoma and painful right S1 metastasis. Transaxial iodine-131 SPECT CT image demonstrates increased radiopharmaceutical uptake in the right S1, compatible with metastasis (A). Transaxial intraprocedural CT images demonstrate coaxial placement of 2 Perc-17 Endocare cryoprobes within the right S1 lesion (B and C, short arrow). Thermal protection is performed by placement of a thermocouple and a spinal needle within the right S1 neuroforamen (B, long black arrow) and injection of carbon dioxide into the right S1 neuroforamen with epidural extension (B and C, white arrows). A 24-month postcryoablation FDG PET/CT demonstrates complete local tumor control with no evidence of metabolically active tumor (D, arrow).

BACKGROUND AND PURPOSE

Percutaneous cryoablation has emerged as a minimally invasive technique for the management of osseous metastases. The purpose of this study was to assess the safety and effectiveness of percutaneous imaging-guided spine cryoablation for pain palliation and local tumor control for vertebral metastases.

MATERIALS AND METHODS

Imaging-guided spine cryoablation was performed in 14 patients (31 tumors) with vertebral metastases

3D Printing of Intracranial Aneurysms Using Fused Deposition Modeling Offers Highly Accurate Replications

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The authors evaluated fused deposition modeling for the production of aneurysm models replicating patient-specific anatomy using 3D rotational angiographic data from 10 patients. A hollow model with connectors for silicone tubes was fabricated by using acrylonitrile butadiene styrene, the support material was then dissolved, and the surfaces finished by using NanoSeal. The models were filled with iodinated contrast and 3D rotational angiography was performed. Reproduction of hollow aneurysm models was technically feasible in 8 of 10 cases, and a high level of anatomic accuracy was observed.

Abstract

Figure from Froelich et al -- Editor's Choice
Sample aneurysm geometries. 3D rotational angiography demonstrates a giant fusiform ICA aneurysm (model ID E, left) and a supraophthalmic saccular ICA aneurysm (model ID A, right). Patient anatomy (A and B) and corresponding vascular models (C and D) are shown. Note that the anterior cerebral artery was purposely shortened in model ID A.

BACKGROUND AND PURPOSE

As part of a multicenter cooperation (Aneurysm-Like Synthetic bodies for Testing Endovascular devices in 3D Reality) with focus on implementation of additive manufacturing in neuroradiologic practice, we systematically assessed the technical feasibility and accuracy of several additive manufacturing techniques. We evaluated the method of fused deposition modeling for the production of aneurysm models replicating patient-specific anatomy.

MATERIALS AND METHODS

3D rotational angiographic data from 10 aneurysms were processed to obtain volumetric models suitable for fused deposition modeling. A hollow aneurysm model with connectors for silicone tubes was fabricated by using acrylonitrile butadiene styrene. Support material was dissolved, and surfaces were finished by using NanoSeal. The resulting models were filled with iodinated contrast media. 3D rotational angiography of the models was acquired, and aneurysm geometry was compared with the original patient data.

RESULTS

Reproduction of hollow aneurysm models was technically feasible in 8 of 10 cases, with aneurysm sizes ranging from 41 to 2928

Presurgical Assessment of the Sensorimotor Cortex Using Resting-State fMRI

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Task-based approaches to functional localization of the motor cortex have limitations such as long scanning times and exclusion of patients with severe functional or neurologic disabilities and children. Resting-state fMRI may avoid these difficulties because patients do not perform any goal-directed tasks. Nineteen patients were prospectively evaluated by using task-based and resting-state fMRI to localize sensorimotor function. Independent component analyses were performed to generate spatial independent components reflecting functional brain networks or noise. The motor cortex was successfully and consistently identified by using resting-state fMRI. Hand, foot, and face regions were defined in a comparable fashion with task-based fMRI.

Abstract

Figure from Schneider et al -- Editor's choice
Illustration of expected findings by using rs-fMRI (light gray) and tb-fMRI (dark gray). rs-fMRI is presumed to show the whole motor cortex (possibly bilaterally), whereas a single motor cortex representation (face, hand, or foot) would be obtained by using tb-fMRI.

BACKGROUND AND PURPOSE

The functional characterization of the motor cortex is an important issue in the presurgical evaluation of brain lesions. fMRI noninvasively identifies motor areas while patients are asked to move different body parts. This task-based approach has some drawbacks in clinical settings: long scanning times and exclusion of patients with severe functional or neurologic disabilities and children. Resting-state fMRI can avoid these difficulties because patients do not perform any goal-directed tasks.

MATERIALS AND METHODS

Nineteen patients with diverse brain pathologies were prospectively evaluated by using task-based and resting-state fMRI to localize sensorimotor function. Independent component analyses were performed to generate spatial independent components reflecting functional brain networks or noise. Three radiologists identified the motor components and 3 portions of the motor cortex corresponding to the hand, foot, and face representations. Selected motor independent components were compared with task-based fMRI activation maps resulting from movements of the corresponding body parts.

RESULTS

The motor cortex was …

Bone-Subtracted Spinal CT Angiography Using Nonrigid Registration for Better Visualization of Arterial Feeders in Spinal Arteriovenous Fistulas

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CTA images of the arterial and late arterial phases were used to obtain warped images of the late arterial phase by nonrigid registration that was adjusted to the arterial phase images. R-CTA images were then obtained by subtracting the warped images from the arterial phase images. R-CTA had a higher accuracy compared with conventional spinal CTA (80% versus 47%). The authors conclude that subtracted CTA imaging using nonrigid registration detects feeders of spinal arteriovenous fistulas more accurately and quickly than conventional CTA.

Abstract

Images of an illustrative case of a 53-year-old man (case 5). Spinal digital subtraction angiography of the right ninth ICA (A) shows a feeder and enlarged vein. C-CTA image (B) and R-CTA (C) at the T9 level can detect the feeder (black arrowhead) from the right ninth ICA. In R-CTA with thin-slab maximum-intensity-projection images, assessing the feeder and continuity is easier than with C-CTA. The window level and width of R-CTA are set to 120 and 240, respectively.
Images of an illustrative case of a 53-year-old man (case 5). Spinal digital subtraction angiography of the right ninth ICA (A) shows a feeder and enlarged vein. C-CTA image (B) and R-CTA (C) at the T9 level can detect the feeder (black arrowhead) from the right ninth ICA. In R-CTA with thin-slab maximum-intensity-projection images, assessing the feeder and continuity is easier than with C-CTA. The window level and width of R-CTA are set to 120 and 240, respectively.

BACKGROUND AND PURPOSE

Pretreatment diagnosis for the location of shunts and arterial feeders of spinal arteriovenous fistulas is crucial. This study aimed to evaluate the utility of subtracted CT angiography imaging by using nonrigid registration (R-CTA) in patients with spinal arteriovenous fistulas compared with conventional CTA imaging.

MATERIALS AND METHODS

The records of 15 consecutive subjects (mean age, 65 years; 2 women) who had undergone CTA and digital subtraction angiography for clinically suspected spinal arteriovenous fistula were reviewed. From CTA images obtained at the arterial and late arterial phases, warped images of the late arterial phase were obtained by using nonrigid registration that was adjusted to the arterial phase images. R-CTA images were then obtained by subtracting the warped images from the arterial phase images. The accuracies of using nonrigid registration and conventional spinal CTA

Responses of the Human Brain to Mild Dehydration and Rehydration Explored In Vivo by 1H-MR Imaging and Spectroscopy

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Editor’s Comment

Serial T1WI and 1H-MR spectroscopy data were acquired in 15 healthy individuals at normohydration, at 12 hours of dehydration, and during 1 hour of oral rehydration. Osmotic challenges were monitored by serum measures, including osmolality and hematocrit. With dehydration, serum osmolality increased by 0.67% and brain tissue fluid decreased by 1.63%. MR imaging morphometry demonstrated corresponding decreases of cortical thickness and volumes of the whole brain, cortex, white matter, and hypothalamus/thalamus. These changes reversed during rehydration. The authors conclude that it is essential to control for hydration levels in studies on brain morphometry and metabolism in order to avoid confounding the findings.

Abstract

Cortical thickness analysis. Local changes of cortical thickness (A, red-to-yellow: for thinning on dehydration; blue-to-light blue: for thickening on rehydration). Dehydration primarily induces cortical thinning (upper row), which reverses on rehydration (bottom row). Note that these prevailing changes are not uniformly distributed over the cerebral surface. Changes on the mesial surface (not shown) were slightly less pronounced but similar. The corresponding statistical significance (B, red-to-yellow: for thinning on dehydration; blue-to-light blue: for thickening upon rehydration) is expressed by increasingly lower false-positive probabilities across subjects.

BACKGROUND AND PURPOSE

As yet, there are no in vivo data on tissue water changes and associated morphometric changes involved in the osmo-adaptation of normal brains. Our aim was to evaluate osmoadaptive responses of the healthy human brain to osmotic challenges of de- and rehydration by serial measurements of brain volume, tissue fluid, and metabolites.

MATERIALS AND METHODS

Serial T1-weighted and 1H-MR spectroscopy data were acquired in 15 healthy individuals at normohydration, on 12 hours of dehydration, and during 1 hour of oral rehydration. Osmotic challenges were monitored by serum measures, including osmolality and hematocrit. MR imaging data were analyzed by using FreeSurfer and LCModel.

RESULTS

On

Diagnostic Accuracy of PET, SPECT, and Arterial Spin-Labeling in Differentiating Tumor Recurrence from Necrosis in Cerebral Metastasis after Stereotactic Radiosurgery

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The authors retrospectively reviewed patients treated between 2007–2010 and identified 14 patients with cerebral metastasis who had clinical or radiographic progression following stereotactic radiosurgery and were imaged with arterial spin-labeling (ASL), FDG-PET, and thallium SPECT before stereotactic biopsy. FDG-PET and ASL were equally sensitive in detecting tumor progression (83%). The specificity of ASL was superior to that of the other modalities (100%, 75%, and 50%, respectively). A combination of modalities did not augment the sensitivity, specificity, positive predictive value, or negative predictive value of ASL.

Abstract

CE-MR imaging, thallium SPECT, FDG-PET, and ASL-MR images from case 1 (A) with metastatic renal cell carcinoma to periventricular white matter of the posterior left lateral horn. CE-MR imaging shows new enhancement in the region treated. SPECT was positive while PET and ASL were negative for tumor recurrence. Biopsy of the target region indicated radiation necrosis in case 2 (B) with metastatic breast cancer to the right cerebellum. CE-MR imaging shows new enhancement in the region treated. PET (SUV = 6.6) and ASL were positive for tumor recurrence. Biopsy of the target region indicated tumor recurrence in case 3 (C) with metastatic melanoma to the right inferior frontal cortex. Only PET was positive for tumor recurrence (SUV = 10.7). Biopsy of the target region indicated tumor recurrence.
CE-MR imaging, thallium SPECT, FDG-PET, and ASL-MR images from case 1 (A) with metastatic renal cell carcinoma to periventricular white matter of the posterior left lateral horn. CE-MR imaging shows new enhancement in the region treated. SPECT was positive while PET and ASL were negative for tumor recurrence. Biopsy of the target region indicated radiation necrosis in case 2 (B) with metastatic breast cancer to the right cerebellum. CE-MR imaging shows new enhancement in the region treated. PET (SUV = 6.6) and ASL were positive for tumor recurrence. Biopsy of the target region indicated tumor recurrence in case 3 (C) with metastatic melanoma to the right inferior frontal cortex. Only PET was positive for tumor recurrence (SUV = 10.7). Biopsy of the target region indicated tumor recurrence.

BACKGROUND AND PURPOSE

Radiographic assessment of cerebral metastasis after stereotactic radiosurgery remains a major challenge in neuro-oncology. It is often difficult to distinguish tumor progression from radiation necrosis in this setting using conventional MR imaging. The objective of this study was to compare the diagnostic sensitivity and specificity of different functional imaging modalities for detecting tumor recurrence after stereotactic radiosurgery.

MATERIALS AND METHODS

We retrospectively reviewed patients treated between 2007 and 2010 and identified 14 patients with cerebral metastasis who had clinical or

The Contribution of Common Surgically Implanted Hardware to Functional MR Imaging Artifacts

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The authors calculated the BOLD-dependent MR imaging artifact impact arising from surgically implanted hardware through a retrospective analysis of fMRIs acquired from 2006–2014. Mean artifact volume associated with intracranial hardware was 4.3 cubic centimeters. The mean artifact volume from extracranial hardware in patients with cerebrovascular disease was 28.4 cubic centimeters. Artifacts had no-to-mild effects on clinical interpretability in all patients with intracranial implants. Extracranial hardware artifacts had no-to-moderate impact on clinical interpretability. The exceptions to interpretability in the face of hardware were ventriculoperitoneal shunts, particularly those with programmable valves and siphon gauges, and large numbers of KLS-Martin maxDrive screws.

Abstract

A representative patient (patient 3) with an intracranial implant. Signal drop-out from a left MCA Pharos Vitesse stent (Codman Neurovascular) is apparent on the magnitude BOLD fMRI image (A, white arrow), resulting in a total artifact volume of 2.1 cm3, which only mildly affected clinical interpretation of the examination. The patient was evaluated 2 years following implantation of the Pharos Vitesse stent in a stenosed left MCA. DSA (B) shows in-stent restenosis (black arrow), with corresponding decreased cerebrovascular reactivity (normalized CVR: voxel CVR normalized to cerebellar CVR) in the left MCA territory (C). In contrast, there is relative symmetry of the temporal signal-to-noise ratio (tSNR) map (D), suggesting that the asymmetric hemodynamic findings are not attributable to artifacts.
A representative patient (patient 3) with an intracranial implant. Signal drop-out from a left MCA Pharos Vitesse stent (Codman Neurovascular) is apparent on the magnitude BOLD fMRI image (A, white arrow), resulting in a total artifact volume of 2.1 cm3, which only mildly affected clinical interpretation of the examination. The patient was evaluated 2 years following implantation of the Pharos Vitesse stent in a stenosed left MCA. DSA (B) shows in-stent restenosis (black arrow), with corresponding decreased cerebrovascular reactivity (normalized CVR: voxel CVR normalized to cerebellar CVR) in the left MCA territory (C). In contrast, there is relative symmetry of the temporal signal-to-noise ratio (tSNR) map (D), suggesting that the asymmetric hemodynamic findings are not attributable to artifacts.

BACKGROUND AND PURPOSE

Blood oxygenation level–dependent MR imaging is increasingly used clinically to noninvasively assess cerebrovascular reactivity and/or language and motor function. However, many patients have metallic implants, which will induce susceptibility artifacts, rendering the functional information uninformative. Here, we calculate and interpret blood oxygenation level–dependent MR imaging artifact impact arising from surgically implanted hardware.

MATERIALS AND METHODS

A retrospective analysis of all blood oxygenation level–dependent MRIs (n = 343; B0 = 3T; TE = 35 ms; gradient …