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Dedicated Breast CT: Feasibility for Monitoring Neoadjuvant Chemotherapy Treatment

Wed, 05/27/2015 - 3:52pm

OBJECTIVES: In this prospective pilot study, the feasibility of non-contrast dedicated breast computed tomography (bCT) to determine primary tumor volume and monitor its changes during neoadjuvant chemotherapy (NAC) treatment was investigated.

MATERIALS AND METHODS: Eleven women who underwent NAC were imaged with a clinical prototype dedicated bCT system at three time points - pre-, mid-, and post-treatment. The study radiologist marked the boundary of the primary tumor from which the tumor volume was quantified. An automated algorithm was developed to quantify the primary tumor volume for comparison with radiologist's segmentation. The correlation between pre-treatment tumor volumes from bCT and MRI, and the correlation and concordance in tumor size between post-treatment bCT and pathology were determined.

RESULTS: Tumor volumes from automated and radiologist's segmentations were correlated (Pearson's r = 0.935, P < 0.001) and were not different over all time points [P = 0.808, repeated measures analysis of variance (ANOVA)]. Pre-treatment tumor volumes from MRI and bCT were correlated (r = 0.905, P < 0.001). Tumor size from post-treatment bCT was correlated with pathology (r = 0.987, P = 0.002) for invasive ductal carcinoma larger than 5 mm and the maximum difference in tumor size was 0.57 cm. The presence of biopsy clip (3 mm) limited the ability to accurately measure tumors smaller than 5 mm. All study participants were pathologically assessed to be responders, with three subjects experiencing complete pathologic response for invasive cancer and the reminder experiencing partial response. Compared to pre-treatment tumor volume, there was a statistically significant (P = 0.0003, paired t-test) reduction in tumor volume at mid-treatment observed with bCT, with an average tumor volume reduction of 47%.

CONCLUSIONS: This pilot study suggests that dedicated non-contrast bCT has the potential to serve as an expedient imaging tool for monitoring tumor volume changes during NAC. Larger studies are needed in future.

Gadoxetate disodium-enhanced liver MRI: gallbladder opacification patterns during hepatobiliary phase

Wed, 05/27/2015 - 3:52pm

OBJECTIVE(S): To describe the different patterns of gallbladder lumen opacification on gadoxetate disodium-enhanced liver magnetic resonance imaging (MRI).

METHODS: One hundred eighty-seven MRI examinations were reviewed by two abdominal imaging radiologists who described the different patterns of gallbladder opacification, based on comparing the post-contrast to the pre-contrast images.

RESULTS: Four patterns of gallbladder opacification were identified, all based on the anti-dependent distribution of the excreted biliary contrast inside the gallbladder lumen. Contrast was identified at the level of the gallbladder neck, anti-dependant wall, and gallbladder fundus. One gallbladder completely filled with contrast.

CONCLUSION(S): The opacification of the gallbladder lumen follows a distinctive anti-dependent distribution.

Delayed splenic rupture presenting 70 days following blunt abdominal trauma

Wed, 05/27/2015 - 3:52pm

Delayed splenic rupture following conservative management of splenic injury is an extremely rare complication. We report a case of an adult patient who presented with delayed splenic rupture necessitating splenectomy, 2 months following blunt abdominal trauma. Imaging at the initial presentation demonstrated only minimal splenic contusion and the patient was discharge following 24 hours of observation.

Target delineation for radiosurgery of a small brain arteriovenous malformation using high-resolution contrast-enhanced cone beam CT

Wed, 05/27/2015 - 3:52pm

Three years following endovascular embolization of a 3 mm ruptured arteriovenous malformation (AVM) of the left superior colliculus in a 42-year-old man, digital subtraction angiography showed continuous regrowth of the lesion. Thin-slice MRI acquired for treatment planning did not show the AVM nidus. The patient was brought back to the angiography suite for high-resolution contrast-enhanced cone beam CT (VasoCT) acquired using an angiographic c-arm system. The lesion and nidus were visualized with VasoCT. MRI, CT and VasoCT data were transferred to radiation planning software and mutually co-registered. The nidus was annotated for radiation on VasoCT data by an experienced neurointerventional radiologist and a dose/treatment plan was completed. Due to image registration, the treatment area could be directly adopted into the MRI and CT data. The AVM was completely obliterated 10 months following completion of the radiosurgery treatment.

Correlation of apparent diffusion coefficient with Ki-67 proliferation index in grading meningioma

Wed, 05/27/2015 - 3:52pm

OBJECTIVE: A noninvasive method to predict aggressiveness of high-grade meningiomas would be desirable because it would help anticipate tumor recurrence and improve tumor management and the treatment outcomes. The Ki-67 protein is a marker of tumor proliferation, and apparent diffusion coefficient (ADC) is related to tumor cellularity. Therefore, we sought to determine whether there is a statistically significant correlation between ADC and Ki-67 values in meningiomas and whether ADC values can differentiate various meningioma subtypes.

MATERIALS AND METHODS: MRI examinations and histopathology of 68 surgically treated meningiomas were retrospectively reviewed. Mean ADC values were derived from diffusion imaging. Correlation coefficients were calculated for mean ADC and Ki-67 proliferation index values using linear regression. An independent unpaired Student t test was used to compare the ADC and Ki-67 proliferation index values from low-grade and more aggressive meningiomas.

RESULTS: A statistically significant inverse correlation was found between ADC and Ki-67 proliferation index for low-grade and aggressive meningiomas (r(2) = -0.33, p = 0.0039). ADC values (+/- SD) of low-grade meningiomas (0.84 +/- 0.14 x 10(-3) mm(2)/s) and aggressive (atypical or anaplastic) meningiomas (0.75 +/- 0.03 x 10(-3) mm(2)/s) were significantly different (p = 0.0495). Using an ADC cutoff value of 0.70 x 10(-3) mm(2)/s, the sensitivity for diagnosing aggressive meningiomas was 29%, specificity was 94%, positive predictive value was 67%, and negative predictive value was 75%.

CONCLUSION: ADC values correlate inversely with Ki-67 proliferation index and help differentiate low-grade from aggressive meningiomas.

Use of intermediate guide catheters as an adjunct in extracranial embolization to avoid onyx reflux into the anastomotic vasculature. A technical note

Wed, 05/27/2015 - 3:52pm

Onyx is a non-adhesive polymer used for embolization of arteriovenous malformations and dural arteriovenous fistulas (DAVFs). The limiting factor for Onyx embolization is usually the amount of microcatheter reflux, which can be safely tolerated. The dual microcatheter technique, compliant balloon use proximally and the use of the dual lumen Scepter balloon have been described to prevent and limit proximal Onyx reflux. We describe the use the Navien 058 intermediate guide catheter to accept the Onyx reflux in its lumen and possibly also serve as a mechanical barrier to avoid reflux into the anastomotic channel connecting the occipital artery to the vertebral artery during DAVF embolization via the occipital artery. Complete embolization of the DAVF was achieved using the lumen of the Navien catheter to accept aggressive Onyx reflux. Complete cure of the DAVF was obtained with Onyx cast filling the entire venous pouch. Besides providing distal access support, intermediate guide catheters can also prevent embolic material reflux by accepting reflux into the lumen and providing a mechanical barrier.

Flow diverter stents for unruptured saccular anterior circulation perforating artery aneurysms: safety, efficacy, and short-term follow-up

Wed, 05/27/2015 - 3:52pm

BACKGROUND: Anterior circulation perforating artery aneurysms including anterior choroidal artery and lenticulostriate artery aneurysms are rare. Injury to these vessels can lead to severe debilitating symptoms.

OBJECTIVE: To present a new approach to treatment using flow diversion technology.

METHODS: Patients treated with a Pipeline embolization device (PED) for perforator artery aneurysms at our institution between June 2012 and May 2013 were identified and included in our retrospective analysis. We evaluated patient vascular risk factors; family history of aneurysms; aneurysm characteristics; National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) on admission; and angiography follow-up and patient clinical outcome at discharge, 6 months, and 1 year.

RESULTS: We included four patients with a mean age of 59.8 years. Two patients had a positive family history of aneurysms. Patient vascular risk factors included smoking, dyslipidemia, and hypertension. All patients presented with a NIHSS and mRS of 0 on admission. Aneurysms were located at the anterior choroidal (n=2) or lenticulostriate artery (n=2) and were treated with a single PED. No periprocedural or postprocedural complications occurred. The patients were discharged with no change in NHISS or mRS score. Six-month and 1-year follow-up angiography showed complete aneurysm occlusion. Mild intimal hyperplasia was seen in 2 cases at 6 months, but was resolved at the 1-year follow-up. No re-treatment was necessary. NIHSS and mRS remained 0 at follow-up time points.

CONCLUSIONS: Our preliminary results show that flow diversion technology is an effective and safe therapy for complex, hard-to-treat aneurysms in perforating arteries. Larger studies with long-term follow-up are needed to validate our promising results.

ACR Appropriateness Criteria(R) Right Lower Quadrant Pain-Suspected Appendicitis

Wed, 05/27/2015 - 3:52pm

The most common cause of acute right lower quadrant (RLQ) pain requiring surgery is acute appendicitis (AA). This narrative's focus is on imaging procedures in the diagnosis of AA, with consideration of other diseases causing RLQ pain. In general, Computed Tomography (CT) is the most accurate imaging study for evaluating suspected AA and alternative etiologies of RLQ pain. Data favor intravenous contrast use for CT, but the need for enteric contrast when intravenous contrast is used is not strongly favored. Radiation exposure concerns from CT have led to increased investigation in minimizing CT radiation dose while maintaining diagnostic accuracy and in using algorithms with ultrasound as a first imaging examination followed by CT in inconclusive cases. In children, ultrasound is the preferred initial examination, as it is nearly as accurate as CT for the diagnosis of AA in this population and without ionizing radiation exposure. In pregnant women, ultrasound is preferred initially with MRI as a second imaging examination in inconclusive cases, which is the majority.The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Adaptation of the modified Bouc-Wen model to compensate for hysteresis in respiratory motion for the list-mode binning of cardiac SPECT and PET acquisitions: testing using MRI

Wed, 05/27/2015 - 3:52pm

PURPOSE: Binning list-mode acquisitions as a function of a surrogate signal related to respiration has been employed to reduce the impact of respiratory motion on image quality in cardiac emission tomography (SPECT and PET). Inherent in amplitude binning is the assumption that there is a monotonic relationship between the amplitude of the surrogate signal and respiratory motion of the heart. This assumption is not valid in the presence of hysteresis when heart motion exhibits a different relationship with the surrogate during inspiration and expiration. The purpose of this study was to investigate the novel approach of using the Bouc-Wen (BW) model to provide a signal accounting for hysteresis when binning list-mode data with the goal of thereby improving motion correction. The study is based on the authors' previous observations that hysteresis between chest and abdomen markers was indicative of hysteresis between abdomen markers and the internal motion of the heart.

METHODS: In 19 healthy volunteers, they determined the internal motion of the heart and diaphragm in the superior-inferior direction during free breathing using MRI navigators. A visual tracking system (vts) synchronized with MRI acquisition tracked the anterior-posterior motions of external markers placed on the chest and abdomen. These data were employed to develop and test the Bouc-Wen model by inputting the vts derived chest and abdomen motions into it and using the resulting output signals as surrogates for cardiac motion. The data of the volunteers were divided into training and testing sets. The training set was used to obtain initial values for the model parameters for all of the volunteers in the set, and for set members based on whether they were or were not classified as exhibiting hysteresis using a metric derived from the markers. These initial parameters were then employed with the testing set to estimate output signals. Pearson's linear correlation coefficient between the abdomen, chest, average of chest and abdomen markers, and Bouc-Wen derived signals versus the true internal motion of the heart from MRI was used to judge the signals match to the heart motion.

RESULTS: The results show that the Bouc-Wen model generated signals demonstrated strong correlation with the heart motion. This correlation was slightly larger on average than that of the external surrogate signals derived from the abdomen marker, and average of the abdomen and chest markers, but was not statistically significantly different from them.

CONCLUSIONS: The results suggest that the proposed model has the potential to be a unified framework for modeling hysteresis in respiratory motion in cardiac perfusion studies and beyond.

Effect of needle gauge and lobe laterality on parenchymal liver biopsy outcome: a retrospective analysis

Wed, 05/27/2015 - 3:52pm

PURPOSE: To analyze the effect of lobe selection, needle gauge, and number of passes on procedure outcomes in terms of specimen length and post-procedure complications.

METHODS: In this HIPAA-compliant, IRB-approved retrospective study, the data from 771 ultrasound-guided adult parenchymal liver biopsies were analyzed. Post-procedure complications were assigned a 3-point rating scale. Associations between specimen length and post-procedure complications with lobe laterality, needle gauge, and number of passes were analyzed. Multivariate logistic regression models were used to analyze the likelihood for achieving a specimen length of at least 2 cm.

RESULTS: Post-procedure complications were not associated with lobe laterality, needle gauge, and number of passes (p > 0.3). Specimen length was associated with the number of passes dichotomized at the study mean (p = 0.007), but not with lobe laterality or needle gauge (p > 0.2). After adjusting for lobe laterality and needle gauge, procedures with 1 or 2 passes were associated with a higher likelihood of obtaining a 2 cm or longer specimen (OR 2.469; CI 1.08-5.63, p = 0.0315) than procedures with 3 or more passes, possibly due to poorer sample quality. After adjusting for lobe laterality, an 18-gauge needle was associated with higher odds of a biopsy procedure with 1 or 2 passes (OR 3.665; CI 1.93-6.95, p < 0.0001) than a 20-gauge needle.

CONCLUSIONS: Lobe laterality was not associated with specimen length or post-procedure complications. An 18-gauge needle compared to a 20-gauge needle could reduce the need for a procedure with more than 2 passes. There was no difference in post-procedure complications between the two needle sizes.

ACR Appropriateness Criteria(R) acute pancreatitis

Wed, 05/27/2015 - 3:51pm

The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every two years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment. The Atlanta Classification by the Acute Pancreatitis Classification Working Group recently modified the terminology for the clinical course and the morphologic changes identified on imaging, primarily contrast- enhanced multidetector computed tomography (MDCT). The two distinct clinical courses of the disease are classified as (1) early phase, which lasts approximately 1 week, and (2) late phase, which starts after the first week and can last for months after the initial episode. The two, primary, morphologic changes are acute, interstitial edematous and necrotizing pancreatitis. Timing of imaging, primarily MDCT, is based on the clinical phases and is, therefore, important for these imaging guidelines. Ultrasound's role is to detect gallstones after the first episode. MDCT plays a primary role in the management of acutely ill patients, only after a minimum of 48-72 hours and generally after one week. MR plays a supplementary role to MDCT. Follow-up MDCT guides management and therapy: percutaneous aspiration of fluid collections and/or placement of large caliber catheters in infected necrosis.

Diffuse bone marrow sarcoid-like reaction associated with renal cell carcinoma

Wed, 05/27/2015 - 3:51pm

Sarcoid-like reaction has been documented in association with several types of malignancy, including renal cell carcinoma. We report the case of a 41-year-old man with nonmetastatic renal cell carcinoma and concomitant non-caseating granulomas distributed diffusely throughout the bone marrow. The granulomas resolved after nephrectomy. As far as we know, this is the first reported case of a sarcoid-like reaction primarily involving the bone marrow in association with renal cell carcinoma.

Leucine-rich glioma-inactivated protein 1 antibody encephalitis: A case report

Wed, 05/27/2015 - 3:51pm

OBJECTIVE: To describe a case of leucine-rich glioma-inactivated protein 1 (LGI1) antibody-associated encephalitis.

METHODS: The clinical and ancillary data and brain MRIs were gathered retrospectively by chart review. Relevant literature on similar cases was also reviewed.

RESULTS: The diagnosis of LGI1 antibody-associated autoimmune encephalitis was based on the typical clinical presentation of seizures, psychiatric symptoms, and memory loss as well as negative diagnostic testing for cancer; the diagnosis was confirmed by positive LGI1 antibody. The patient responded favorably to treatment with IV immunoglobulin and continues to do well.

CONCLUSION: LGI1 antibody-associated encephalitis has increasingly been recognized as a primary autoimmune disorder with good prognosis and response to treatment.

Flow artifact in the anterior communicating artery resembling aneurysm on the time of flight MR angiogram

Wed, 05/27/2015 - 3:51pm

BACKGROUND: Magnetic resonance angiogram (MRA) of the brain is a widely employed non-invasive test to diagnose aneurysms. However, its overall accuracy is less than digital subtraction angiography and is prone to give false-positive or false-negative results. False-negative results can be seen with hemorrhage, lipoma, dermoid, posterior lobe of the pituitary gland, and the flow artifacts.

PURPOSE: To describe the findings associated with false aneurysms in the anterior communicating artery on the time of flight MRA and review the physical principles behind this artifact.

MATERIAL AND METHODS: This short series comprises of four patients whose MRA showed suspicious aneurysms in the region of the anterior communicating artery (ACOM) on time of flight MRA.

RESULTS: Two patients underwent catheter angiogram and the other two patients had computed tomography angiogram. None of these cases proved to have aneurysms and normal anterior communicating arteries were seen in all the patients. The findings on the MR angiograms were considered artifacts. All of the pseudoaneurysm had tapered appearance.

CONCLUSION: MR angiogram can result in artifacts at ACOM which may be mistaken for aneurysm. Such pseudoaneurysms have characteristic appearance and should be followed up with non-invasive tests.

Risk of distal embolization with stent retriever thrombectomy and ADAPT

Wed, 05/27/2015 - 3:51pm

BACKGROUND: There is a discrepancy in clinical outcomes and the achieved recanalization rates with stent retrievers in the endovascular treatment of ischemic stroke. It is our hypothesis that procedural release of embolic particulate may be one contributor to poor outcomes and is a modifiable risk. The goal of this study is to assess various treatment strategies that reduce the risk of distal emboli.

METHODS: Mechanical thrombectomy was simulated in a vascular phantom with collateral circulation. Hard fragment-prone clots (HFC) and soft elastic clots (SECs) were used to generate middle cerebral artery (MCA) occlusions that were retrieved by the Solitaire FR devices through (1) an 8 Fr balloon guide catheter (BGC), (2) a 5 Fr distal access catheter at the proximal aspect of the clot in the MCA (Solumbra), or (3) a 6 Fr guide catheter with the tip at the cervical internal carotid artery (guide catheter, GC). Results from mechanical thrombectomy were compared with those from direct aspiration using the Penumbra 5MAX catheter. The primary endpoint was the size distribution of emboli to the distribution of the middle and anterior cerebral arteries.

RESULTS: Solumbra was the most efficient method for reducing HFC fragments (p 1000 microm) was significantly increased using GC. A non-statistically significant benefit of direct aspiration was observed in several subgroups of emboli with size 50-1000 microm. However, compared with the stent-retriever mechanical thrombectomy techniques, direct aspiration significantly increased the risk of SEC fragmentation ( < 50 microm) by at least twofold.

CONCLUSIONS: The risk of distal embolization is affected by the catheterization technique and clot mechanics. already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Targeted drug delivery to flow-obstructed blood vessels using mechanically activated nanotherapeutics

Wed, 05/27/2015 - 3:51pm

Obstruction of normal blood flow, which occurs in a variety of diseases, including thromboembolism in stroke and atherosclerosis, is a leading cause of death and long-term adult disability in the Western world. This review focuses on a novel nanotherapeutic drug-delivery platform that is mechanically activated within blood vessels by high-fluid shear stresses to selectively target drugs to sites of vascular obstruction. In vitro and in vivo studies have shown that this approach can be used to efficiently lyse clots using a significantly lower amount of thrombolytic drug than is required when administered in a soluble formulation. This nanotherapeutic strategy can potentially improve both the efficacy and safety of thrombolytic drugs, particularly in patients who are at high risk for brain hemorrhage, and thus provide a new approach for the treatment of many life-threatening and debilitating vascular disorders.

Quantitative analysis of high-resolution, contrast-enhanced, cone-beam CT for the detection of intracranial in-stent hyperplasia

Wed, 05/27/2015 - 3:51pm

BACKGROUND: Intracranial in-stent hyperplasia is a stroke-associated complication that requires routine surveillance. OBJECTIVE: To compare the results of in vivo experiments to determine the accuracy and precision of in-stent hyperplasia measurements obtained with modified C-arm contrast-enhanced, cone-beam CT (CE-CBCT) imaging with those obtained by 'gold standard' histomorphometry. Additionally, to carry out clinical analyses comparing this CE-CBCT protocol with digital subtraction angiography (DSA). METHODS: A non-binned CE-CBCT protocol (VasoCT) was used that acquires x-ray images with a small field-of-view and applies a full-scale reconstruction algorithm providing high-resolution three-dimensional (3D) imaging with 100 microm isotropic voxels. In an vivo porcine model, VasoCT cross-sectional area measurements were compared with gold standard vessel histology. VasoCT and DSA were used to calculate in-stent stenosis in 23 imaging studies. RESULTS: Porcine VasoCT cross-sectional stent, lumen, and in-stent hyperplasia areas strongly correlated with histological measurements (r(2)=0.97, 0.93, 0.90; slope=1.14, 1.07, and 0.76, respectively; p<0.0001). Clinical VasoCT percentage stenosis correlated well with DSA percentage stenosis (r(2)=0.84; slope=0.76), and the two techniques were free of consistent bias (Bland-Altman, bias=3.29%; 95% CI -14.75% to 21.33%). An illustrative clinical case demonstrated the advantages of VasoCT, including 3D capability and non-invasive IV contrast administration, for detection of in-stent hyperplasia. CONCLUSIONS: C-arm VasoCT is a high-resolution 3D capable imaging technique that has been validated in an animal model for measurement of in-stent tissue growth. Successful clinical implementation of the protocol was performed in a small case series. already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.