Treatment verification in high dose rate brachytherapy using a realistic 3D printed head phantom and an imaging panel

PURPOSEEven though High Dose Rate (HDR) brachytherapy has good treatment outcomes in different treatment sites, treatment verification is far from widely implemented because of a lack of easily available solutions. Previously it has been shown that an imaging panel (IP) near the patient can be used to determine treatment parameters such as the dwell time and source positions in a single material pelvic phantom. In this study we will use a heterogeneous head phantom to test this IP approach, and simulate common treatment errors to assess the sensitivity and specificity of the error-detecting capabilities of the IP.METHODS AND MATERIALSA heterogeneous head-phantom consisting of soft tissue and bone equivalent materials was 3D-printed to simulate a base of tongue treatment. An High Dose Rate treatment plan with 3 different catheters was used to simulate a treatment delivery, using dwell times ranging from 0.3 s to 4 s and inter-dwell distances of 2 mm. The IP was used to measure dwell times, positions and detect simulated errors. Measured dwell times and positions were used to calculate the delivered dose.RESULTSDwell times could be determined within 0.1 s. Source positions were measured with submillimeter accuracy in the plane of the IP, and average distance accuracy of 1.7 mm in three dimensions. All simulated treatment errors (catheter swap, catheter shift, afterloader errors) were detected. Dose calculations show slightly different distributions with the measured dwell positions and dwell times (gamma pass rate for 1 mm/1% of 96.5%).CONCLUSIONSUsing an IP, it was possible to verify the treatment in a realistic heterogeneous phantom and detect certain treatment errors.     

Remarkable anatomic variations in paranasal sinus region and their clinical importance

With the advent of functional endoscopic sinus surgery (FESS) and coronal computed tomography (CT) imaging, considerable attention has been directed toward paranasal region anatomy. Detailed knowledge of anatomic variations in paranasal sinus region is critical for surgeons performing endoscopic sinus surgery as well as for the radiologist involved in the preoperative work-up. To be in the known anatomical variants with some accompanying pathologies, directly influence the success of diagnostic and therapeutic management of paranasal sinus diseases. A review of 512 (1024 sides) paranasal sinus tomographic scans was carried out to expose remarkable anatomic variations of this region. We used only coronal sections, but for some cases to clear exact diagnosis, additional axial CT scan, magnetic resonance imaging (MRI) and nasal endoscopy were also performed. In this pictorial essay, rates of remarkable anatomic variations in paranasal region were displayed. The images of some interesting cases were illustrated, such as the Onodi cell in which isolated mucocele caused loss of visual acuity, agger nasi cell, Haller's cell, uncinate bulla, giant superior concha bullosa, inferior concha bullosa, bilateral carotid artery protrusion into sphenoid sinus, maxillary sinus agenesis, bilateral secondary middle turbinate (SMT) and sphenomaxillary plate. The clinical importance of all these variations were discussed under the light of the literature. It was suggested that remarkable anatomic variations of paranasal region and their possible pathologic consequences should be well defined in order to improve success of management strategies, and to avoid potential complications of endoscopic sinus surgery. The radiologist must pay close attention to anatomical variations in the preoperative evaluation.     

Fat-suppressed MR of the orbit and cavernous sinus: comparison of fast spin-echo and conventional spin-echo.

PURPOSETo compare T2-weighted fat-suppressed fast spin-echo imaging with fat-suppressed conventional spin-echo imaging in the detection of normal intraorbital and pericavernous anatomy and orbital disease, and to determine the efficacy of fat saturation with T2-weighted fast spin-echo imaging of the cavernous sinus.METHODSContrast-to-noise ratios of normal intraorbital anatomy were calculated and compared in 10 consecutive patients using fat-suppressed fast spin-echo and conventional spin-echo T2-weighted images. Contrast-to-noise ratios of common intraorbital lesions were calculated and compared using fat-suppressed fast spin-echo and fat-suppressed conventional spin-echo. Qualitative evaluation was performed and compared for normal intraorbital anatomy using both fat-suppressed fast spin-echo and fat-suppressed conventional spin-echo in 16 patients. Qualitative evaluation for the detection of normal anatomic structures of the pericavernous region was performed and compared using fast spin-echo with and without fat suppression and fat-suppressed conventional spin-echo T2-weighted images in 16 patients. Fat saturation was performed using standard commercially available chemical saturation technique.RESULTSReduced imaging time allowed more acquisitions for fat-suppressed fast spin-echo images, which significantly improved visibility of intraorbital and pericavernous anatomy over fat-suppressed conventional spin-echo. Anatomic visibility was also improved because of reduced motion, phase encoding, and susceptibility artifacts. There was no significant difference between contrast-to-noise ratios for fat-suppressed fast spin-echo and fat-suppressed conventional spin-echo imaging of the lateral and medial rectus muscles. Contrast-to-noise ratios of fat suppressed fast spin-echo of orbital disease was significantly greater than contrast-to-noise ratios of fat-suppressed conventional spin-echo. Detection of several normal anatomic structures of the pericavernous region was significantly improved with non-fat-suppressed fast spin-echo over fat-suppressed fast spin-echo because of significantly reduced magnetic susceptibility artifact.CONCLUSIONSFat-suppressed fast spin-echo is superior to fat-suppressed conventional spin-echo for T2-weighted orbital imaging. Non-fat-suppressed fast spin-echo is the preferred pulse sequence for T2-weighted imaging of the cavernous sinus because of the minimal susceptibility artifact.     

Variations of sphenoid and related structures

The aim of this study was to delineate the precise relationship between the sphenoid sinus and internal carotid artery and the optic nerve, as well as to assess incidence of the anatomic variations of these structures. A review of 92 paranasal sinus tomographic scans was made for anatomic variations of the sphenoid sinus and related bony and neurovascular structures. Coronal and axial tomographic sections were obtained with 2.5-mm section thickness. We assessed the protrusion of the internal carotid artery (ICA) and the optic nerve (ON) into the sphenoid sinus, bone dehiscence of these structures, and pneumatization of the anterior clinoid process (ACP) and pterygoid recess (PR), as well as the variations of the sphenoid sinus septum. The protrusion of the ICA into the sphenoid sinus was found in 24 (26.1 %) patients. An ON protrusion was present in 29 (31.5 %) patients. Pneumatization of the PR was encountered in 27 (29.3 %) patients. There was not a statistically significant relationship between the pneumatization of the PR and ICA protrusion into the sphenoid sinus (χ ² = 0.258, p = 0.168). A significant relationship between the ACP pneumatization and protrusion of the ON into the sphenoid sinus was found (χ ² = 0.481, p = 0.007). Preoperative recognition of the anatomic variations by the radiologist is beneficial for identification of the limits of dissection. This is particularly important in the sphenoid sinus area where extensive pneumatization of the skull base bones may distort the anatomic configuration. Therefore, axial and coronal CT sections should always be obtained prior to any surgery in the sphenoid sinus area. Received: 27 January 1999; Revised: 12 August 1999; Accepted: 1 September 1999     

Evaluation of variations in sinonasal region with computed tomography

AIM: To investigate the frequency of anatomical variations in sinonasal region and association of these variations with mucosal diseases.METHODS: The study included 400 cases (191 female and 209 male) who were considered to have preliminary diagnoses of sinonasal pathology and who had paranasal sinus computed tomography (CT) examination in axial plane. Reformatted CT images were studied in all planes.RESULTS: Age range of the patients was 20-83 (mean 40.26 ± 14.85). Most commonly detected anatomical variation was Agger nasi cell (74.8%). There was a significant association between clinoid process pneumatization and protrusion of internal carotid arteries and optic nerves into sphenoid sinus (P < 0.001). Besides, the relationships between pterygoid process pneumatization and protrusion of vidian nerve into sphenoid sinus, and between pneumatization of large sphenoid wing and protrusion of maxillary nerves into sphenoid sinus were also significant (P < 0.001). Uncinate bulla and giant ethmoid bulla were found to be significantly associated with sinonasal mucosal diseases (P = 0.004 and P = 0.002, respectively).CONCLUSION: Sinonasal region has a great number of variations, and some of them have been determined to be associated with sinonasal mucosal disease. It is necessary to know that some of these variations are associated with protrusion of significant structures such as carotid artery or optic nerve into the sinus and care should be observed in surgeries on patients carrying these variations.     

MR imaging features of tuberculosis of the sellar region

PurposeTuberculosis of the sellar region, especially the pituitary gland, is rare. The purpose of this article is to demonstrate through a review of five clinical cases the value of imaging, especially MR imaging, in the evaluation of this pathology.Patients and methodsCT and MRI of the brain were obtained in all cases along with a chest radiograph.ResultsFour patterns were detected on MRI: pituitary tuberculoma mimicking adenoma; pituitary abscess, extending to the cavernous sinus in one case and associated with infundibulum thickening in another; hypophysitis with suprasellar extension in association with tuberculous meningoencephalitis; and infundibular thickening associated with tuberculous meningoencephalitis. Diagnosis was based on biopsy in two cases and combination of imaging and clinical data in three cases. Outcome was favorable with anti-tuberculosis drugs.ConclusionIrrespective of the imaging features, a history of travel to an endemic region combined to other findings such as infundibular thickening should raise concern for the possibility of tuberculosis even in the absence of signs of systemic infection.     

Región selar: evaluación mediante resonancia magnética de lesiones tumorales y pseudotumorales de baja frecuencia

ObjectiveTo show the usefulness of magnetic resonance imaging in the anatomic and pathologic characterization of the sellar region, emphasizing the differential diagnosis of uncommon non-adenomatous tumors and pseudotumors studied in our institution.ConclusionThe sellar region is a complex anatomic space with diverse types of tissues from which a wide spectrum of diseases can arise. Magnetic resonance imaging's high tissue resolution and ability to characterize the patterns of tumor growth and biological behavior make it the best imaging technique to study this region.     

An integrated system for clinical treatment verification of HDR prostate brachytherapy combining source tracking with pretreatment imaging

PurposeHigh-dose-rate (HDR) prostate brachytherapy treatment is usually delivered in one or a few large dose fractions. Poor execution of a planned treatment could have significant clinical impact, as high doses are delivered in seconds, and mistakes in an individual fraction cannot be easily rectified. Given that most potential errors in HDR brachytherapy ultimately lead to a geographical miss, a more direct approach to verification of correct treatment delivery is to directly monitor the position of the source throughout the treatment. In this work, we report on the clinical implementation of our treatment verification system that uniquely combines the 2D source-tracking capability with 2D pretreatment imaging, using a single flat panel detector (FPD).Methods and MaterialsThe clinical brachytherapy treatment couch was modified to allow integration of the FPD into the couch. This enabled the patient to be set up in the brachytherapy bunker in a position that closely matched that at treatment planning imaging. An anteroposterior image was acquired of the patient immediately before treatment delivery and was assessed by the Radiation Oncologist online, to reestablish the positions of the catheters relative to the prostate. Assessment of catheter positions was performed in the left-right and superior-inferior directions along the entire catheter length and throughout the treatment volume. Source tracking was then performed during treatment delivery, and the measured position of the source dwells were directly compared to the treatment plan for verification.ResultsThe treatment verification system was integrated into the clinical environment without significant change to workflow. Two patient cases are presented in this work to provide clinical examples of this system, which is now in routine use for all patient treatments in our clinic. The catheter positions were visualized relative to the prostate, immediately before treatment delivery. For one of the patient cases presented in this work, they agreed with the treatment plan on average by 1.5 mm and were identifiable as a predominantly inferior shift. The source tracking was performed during treatment delivery, and for the same case, the mean deviation from the planned dwell positions was 1.9 mm (max = 4.9 mm) for 280 positions across all catheters.ConclusionWe have implemented our noninvasive treatment verification system based on an FPD in the clinical environment. The device is integrated into a patient treatment couch, and the process is now included in the routine clinical treatment procedure with minor impact on workflow. The system which combines both 2D pretreatment imaging and HDR 2D source tracking provides a range of information that can be used for comprehensive treatment verification. The system has the potential to meaningfully improve safety standards by allowing widespread adoption of routine treatment verification in HDR brachytherapy.     

Typical MR imaging findings of perianal infections in patients with hematologic malignancies

ObjectiveWe aimed to investigate the MR imaging findings of patients with hematologic malignancies who have symptoms suggesting perianal infection and to demonstrate the importance of imaging.Subjects and methodsThe study included 36 patients with hematologic malignancies who underwent anorectal MR imaging in our department between September 2011–May 2016. Two radiologists experienced in abdominal radiology viewed the MR images in consensus. Abscesses, fistulous or sinus tracts, signal alterations and contrast enhancement in keeping with an inflammation and edema in the perianal region were recorded.ResultsPerianal abscess was found in 16 of the 36 patients. In 10 of these 16 patients there was also extensive inflammatory signal alterations in perianal and/or perineal soft tissues.In six of the 36 patients perianal fistula was detected. A sinus tract was seen at the level of subcutaneous external anal sphincter in one patient. Inflammatory signal alterations in the surrounding soft tissues were present in three of these seven patients.There were abscesses in labium majus in two patients and in one patient there were perineal abscesses with accompanying inflammatory signal alterations.In six of the 36 patients no abscess or fistula/sinus tract was seen. There were only inflammatory signal alterations with contrast enhancement in perianal or subcutaneous tissues.In two patients presenting with perianal pain and hemorrhoids, minimal inflammatory changes were detected on MR images.There were two patients with normal MR imaging findings.ConclusionAs digital examination of the anorectum and rectoscopy are avoided in neutropenic patients, MR imaging, which clearly demonstrates the perianal pathology should be preferential.     

Para-cavernous sinus venous structures: anatomic variations and pathologic conditions evaluated on fat-suppressed 3D fast gradient-echo MR images

BACKGROUND: The cavernous sinus communicates with several para-cavernous sinus venous structures, receiving blood flow from the superficial middle cerebral vein (SMCV), the sphenoparietal sinus (SPS), and the superior ophthalmic vein, and draining into the superior and inferior petrosal sinuses and pterygoid and basilar plexuses. Anatomic variations of these veins have been previously reported; however, some details, such as the relationship between the SPS and the SMCV, are incompletely characterized. The anatomic variations of para-cavernous sinus veins, especially drainage patterns of the SMCV, were evaluated on MR imaging. MATERIALS AND METHODS: Thirty-seven patients, including those without any lesions affecting the cavernous sinus or para-cavernous veins and patients with carotid cavernous fistulas, were examined by using fat-suppressed contrast-enhanced 3D fast gradient-echo MR imaging. Two neuroradiologists evaluated the images on a viewer, regarding the normal anatomy and the pathologic findings of the para-cavernous sinus veins. RESULTS: The fat-suppressed 3D fast gradient-echo MR images clearly depicted the para-cavernous sinus venous structures in all patients. SMCVs had 4 variations in the drainage patterns. The most frequent pattern was drainage into the SPS (39%), and other types were draining into cavernous sinus, pterygoid plexus, and tentorial sinus. The SPS had 3 variations. The most frequent pattern was drainage into cavernous sinus (72%), and others were the hypoplastic type or those draining into pterygoid plexus. CONCLUSION: The fat-suppressed 3D fast gradient-echo MR image is useful for evaluating the venous structures in the skull base. Knowledge of the variations is important for diagnosis and endovascular treatment of the cavernous sinus lesions.     

Trends in Hospital Performance on the Medicare National Outpatient Imaging Metrics: A 5-Year Longitudinal Cohort Analysis

PurposeMedicare established its Hospital Outpatient Quality Reporting Program (HOQRP) to promote and incentivize quality care and appropriate utilization in the hospital outpatient setting. The program includes “imaging efficiency” metrics evaluating appropriate utilization of imaging examinations. Our purpose was to evaluate the longitudinal performance of the nation’s hospitals on the HOQPR’s imaging efficiency metrics.MethodsData were obtained from CMS Hospital Compare for hospitals participating in the Medicare HOQRP during both initial (January 1, 2011, to December 31, 2011) and follow-up (July 1, 2015, to June 30, 2016) periods. The six reported imaging efficiency metrics were: MRI lumbar spine for low back pain, mammography follow-up rates, abdomen and chest CT double scans (imaging with and without intravenous contrast), cardiac imaging for preoperative risk assessment for low-risk surgery, and simultaneous use of brain and sinus CT. Differences in imaging efficiency metrics were calculated using fixed effects linear regression models.ResultsBaseline and follow-up data were available for 3,960 hospitals. Median changes were MRI lumbar spine for low back pain: +3.6% (range: ?27.9% to +31.4%; P < .001); mammography follow-up: ?0.3% (range: ?69.5% to +62.6%; P = .03); double scan abdomen CT: ?1.9% (range: ?73.5% to +32.3%; P < .001); double scan chest CT: ?0.4% (range: ?73.2% to +28.0%; P < .001); preoperative cardiac imaging: ?0.7% (range: ?10.0% to +9.9%; P < .001); simultaneous brain and sinus CT: ?0.9% (range: ?11.8% to +7.8%; P < .001).ConclusionMedicare’s nationwide hospital outpatient imaging efficiency reporting initiative was associating with worse performance in lumbar spine MRI utilization and small improvements in double CT scans. Because quality metrics are increasingly imposed on health care providers, health service researchers will need to rigorously evaluate their effectiveness before and during early implementation.     

CT值用于质子治疗计划系统中质子入射能量的计算

目的 探索CT值用于质子治疗计划系统计算质子入射能量的方法。方法 通过分析Bethe-Block公式和质子射程计算公式,研究质子治疗能量范围(70~250 MeV)质子束在各种辐射等效材料中与水中的射程的比例关系。利用蒙特卡罗方法SRIM2008程序验证此比例系数存在恒值的可能性。通过Origin 8.0软件对此射程比例系数(C_i)和相应辐射等效材料的CT值进行指数函数拟合,研究CT值与射程比例系数的函数关系。分析CT测量原理和利用射程比系数将质子治疗的实际射程等效为水中的射程,从而反推入射质子所需的能量。结果 质子治疗能量范围(70~250 MeV)质子束在辐射等效材料中的射程与此能量质子束在水中的射程的比值存在恒定的比例系数(C_i)。CT值与射程比例系数相关(r=0.999)。可以将特定能量质子在辐射等效材料中的射程等效为水中的射程。结论 本研究利用机体各体积单元CT值与射程比例系数(C_i),精确计算实际照射肿瘤部位所需射程的水中等效射程,由水中等效射程计算出Bragg峰位落在肿瘤部位所需的入射质子束能量。本研究为CT技术用于质子治疗计划系统提出了一种新的探索。     

Migration of Bone Wax into the Sigmoid Sinus after Posterior Fossa Surgery

BACKGROUND AND PURPOSE:Bone wax is a hemostatic agent that has been reported in some instances to migrate into the sigmoid sinus following posterior fossa surgery. The purpose of this study was to characterize the CT and MR imaging findings of this entity.MATERIALS AND METHODS:The study included 212 consecutive patients who underwent posterior fossa surgery and postoperative CT and contrast-enhanced MR imaging. The presence of sigmoid sinus bone wax migration was determined with the following criteria: sigmoid sinus filling defect showing low signal on all MR imaging pulse sequences; sigmoid sinus filling defect showing low CT attenuation, similar to fat attenuation; and clinical confirmation that bone wax was used intraoperatively. CT and MR imaging of an in vitro bone wax sample was also performed.RESULTS:We identified 6 cases of sigmoid sinus bone wax migration. In each case, a low-signal-intensity, low-attenuation filling defect was noted in the sigmoid sinus. The morphology was linear (n = 3) or globular (n = 3). In patients with serial imaging, the appearance of migrated bone wax remained stable over time. No adverse outcomes related to sigmoid sinus bone wax migration were encountered. In vitro imaging of bone wax confirmed low CT attenuation and low MR imaging signal intensity on T1WI and T2WI.CONCLUSIONS:Bone wax migration into the sigmoid sinus is a recognizable imaging finding after posterior fossa surgery that appears to have a benign clinical course. The finding should be distinguished from more serious complications, such as venous sinus thrombosis.

Bone wax is commonly used during the course of posterior fossa craniotomy to control bleeding from emissary veins or to pack violated mastoid air cells. The mastoid emissary vein often lies close to or within the retrosigmoid or suboccipital craniotomy bed and represents a channel in direct communication with the sigmoid sinus.¹ Awareness of the use of this agent is important in assessing postoperative imaging because its presence within a dural venous sinus might be mistaken for air, fat, or thrombus. The particular imaging characteristics of this agent can aid appropriate diagnosis. The appearance has been reported in the literature as low attenuation on CT (intermediate between fat and simple fluid) and as a signal void on MR imaging (attributable to its semicrystalline solid nature).² To our knowledge, only 2 prior studies of sigmoid sinus bone wax migration (including 8 total cases) have been reported in the literature, and conventional MR imaging features of the migrated bone wax were reported in only 1 of these cases.^3,4 The purpose of our study was to describe the CT and MR imaging features of sigmoid sinus bone wax migration after posterior fossa surgery. We also sought to assess the CT and MR imaging features of an in vitro bone wax sample.     

MR appearance of the internal architecture of Ammon's horn.

PURPOSETo determine whether the four subdivisions of Ammon''s horn and six layers of CA1 seen histologically can be demonstrated with MR imaging.METHODSSpecimens of cadaver brains were imaged in a 3.0-T MR imager with a 3.0-cm solenoid coil. The specimens were sectioned, stained, and examined histologically. On anatomic sections, the four subdivisions of Ammon''s horn and six layers of CA1 were identified. The MR images were then compared with the anatomic sections.RESULTSUsing geographic characteristics, we identified the four subdivisions of Ammon''s horn. In CA1, the six layers could be identified by variations in signal intensity, width, and location.CONCLUSIONThis study suggests that, with MR imaging of sufficiently high resolution, the internal architecture of Ammon''s horn may be identified.     

Sodium and proton MR properties of cartilage during compression

Proton and sodium MR relaxation times of bovine articular cartilage specimens were measured as a function of proteoglycan (PG) depletion and as a function of mechanical compression. Proton and sodium relaxation times of normal cartilage were compared with relaxation times of PG-depleted cartilage to evaluate the significance of PG depletion-induced changes in MR relaxation parameters. These comparisons were conducted for both uncompressed and mechanically compressed states. The mechanical compressions were performed with an MR-compatible pressure cell and evaluated dynamically via interleaved one-dimensional proton and sodium MR projection imaging. The comparisons indicate that sodium relaxation parameters are sensitive to PG depletion when cartilage is in a mechanically compressed state or an uncompressed state. In contrast, proton relaxation parameters do not change significantly with PG depletion when cartilage is in an uncompressed state. However, during mechanical compression, proton T2 becomes sensitive to PG depletion. These results support the potential of sodium magnetic resonance imaging (MRI) as a possible modality for obtaining imaging contrast related to PG depletion. The results also indicate the potential of proton MRI to provide such contrast if the image acquisition is conducted in conjunction with a mechanical compression via physical exercise.J. Magn. Reson Imaging 10:961-967, 1999.     

Clinical utility of contrast-enhanced three-dimensional ultrasound imaging with Sonazoid: Findings on hepatocellular carcinoma lesions

ObjectivesWe investigated clinical utility of contrast-enhanced three-dimensional ultrasound (CE 3D US) imaging with contrast medium Sonazoid for demonstrating characteristic enhancement of hepatocellular carcinoma (HCC).MethodsAmong 115 focal liver tumors undergoing CE 3D US imaging, 70 HCCs confirmed with contrast-enhanced multi-detector computed tomography, contrast-enhanced magnetic resonance imaging or histopathologic examination were retrospectively analyzed. CE 3D US imaging was performed using Autosweep 3D scan functionality in the early, middle and late phase, after bolus injection of 0.2 ml Sonazoid. The CE 3D tomographic images reconstructed in parallel slices and sonographic angiogram images were independently reviewed by two reviewers. Kappa values were used to assess inter-reviewers’ agreement.ResultsTUI images showed most of HCCs were detected with intratumoral vessels and early tumor enhancement in the early phase, expressed homogenous or heterogeneous tumor enhancement in the middle phase, and became hypoechoic or isoechoic in the late phase. The kappa values in the early, middle and late phase for inter-reviewer agreements regarding the characteristic enhancement of tumors were 0.817, 0.774, and 0.785. In addition, TUI images demonstrated satellite foci and tortuous tumor vessels in three orthogonal planes. Sonographic angiogram reconstructed by different rendering modes showed the vessels and tumor stain in spatial view. The spatial configuration of anatomic structures was revealed on basis of both TUI and sonographic angiogram images.ConclusionCE 3D US imaging, with spatial visualization, is clinically useful to exhibit the characteristic enhancement of HCC tumors objectively.     

Repeated sinus CT imaging after recent head imaging

ObjectivesExcessive use of sinus CT is a significant problem in medical imaging, resulting in unnecessary costs and radiation exposure. This study assesses frequency of sinus CT performed after recent head imaging has already adequately evaluated the sinuses.MethodsA retrospective search of the PACS database of an academic medical center was performed to identify cases of sinus CT imaging in 2017. Cases were excluded if sinus CT was performed related to trauma, tumor, operative evaluation, or acute infection other than sinusitis (orbital cellulitis, intracranial abscess). Studies with separate imaging covering the sinuses ordered at the same time as sinus CT or performed previously within 4 weeks were identified and clinical information was recorded.ResultsOf 735 sinus CTs performed, 19 (5%) had same-day head imaging and 30 (8%) had previous head imaging within 4 weeks, adding up to a cumulative 13% of cases with recent head imaging. The average patient age was 42, with 13 pediatric cases. Of ordering providers, residents ordered the highest percentage of sinus CTs with same-day head imaging (84%) and previous imaging within 4 weeks (63%). The sinuses were described in all head CT radiology reports, while 10 of 12 brain MRI reports did not mention the sinuses.ConclusionIn one year, 13% of patients receiving sinus CTs at our institution had recent head imaging. A focused education effort for ordering providers to avoid repeating sinus imaging, and for radiology to comment on sinuses on head imaging, may reduce unnecessary sinus CTs.     

Mechanical evaluation of the Bravos afterloader system for HDR brachytherapy

PurposeThe Bravos afterloader system was released by Varian Medical Systems in October of 2018 for high-dose-rate brachytherapy with ¹⁹²Ir sources, containing new features such as the CamScale (a new device for daily quality assurance and system recalibration), channel length verification, and different settings for rigid and flexible applicators. This study mechanically evaluated the Bravos system precision and accuracy for clinically relevant scenarios, using dummy sources.Methods and MaterialsThe system was evaluated after three sets of experiments: (1) The CamScale was used to verify inter- and intra-channel dwelling variability and system calibration; (2) A high-speed camera was used to verify the source simulation cable movement inside a transparent quality assurance device, where dwell positions, dwell times, transit times, speed profiles, and accelerations were measured; (3) The source movement inside clinical applicators was captured with an imaging panel while being exposed to an external kV source. Measured and planned dwell positions and times were compared.ResultsMaximum deviations between planned and measured dwell positions and times for the source cable were 0.4 mm for the CamScale measurements and 0.07 seconds for the high-speed camera measurements. Mean dwell position deviations inside clinical applicators were below 1.2 mm for all applicators except the ring that required an offset correction of 1 mm to achieve a mean deviation of 0.4 mm.ConclusionsFeatures of the Bravos afterloader system provide a robust and precise treatment delivery. All measurements were within manufacturer specifications.     

Detailed imaging of abducens nerve anatomy using contrast-enhanced 3D-TOF MR angiography

PurposeCranial nerves (CNs), particularly CN IV and VI are difficult to visualize with conventional MRI techniques, particularly within the cavernous sinus region. The aim of this study was to evaluate the capacity of high-resolution contrast enhanced 3D time-of-flight (TOF) MR angiography using new generation 3 T imaging technology to provide detailed visualization of CN VI anatomy, particularly within the cavernous sinus and petroclival regions.MethodsTwo neuroradiologists conducted bilateral evaluation of CN VI visibility in 23 patients for nerve segments located in the petroclival segment (dural cave and Dorello's canal), and three divisions of the cavernous sinus. All images were collected using contrast enhanced TOF MR angiography using a new generation 3 T machine.ResultsOf the CN VI segments assessed, average visibility of CN VI was best achieved in Dorello's canal. Overall visibility of CN VI within the regions inspected was best achieved in the axial view, with the exception of the dural cave, which was best assessed using the coronal view.We also identified strong agreement in assessment of nerve visibility between the two reviewers.We also identified a putative CN6 duplication and a small schwannoma, highlighting the fidelity of our approach.ConclusionContrast enhanced 3D TOF MR angiography can visualize CN VI anatomy, particularly within the petrocavernosal region and cavernous sinus with simultaneous visualization of arterial and venous structures. This cannot be easily achieved using traditional MRI techniques. This imaging technique might be used with new generation machines to evaluate CN VI anatomy and pathologies within the petrocavernosal region and cavernous sinus, especially relating to vascular pathologies.     

Benign versus secondary-progressive multiple sclerosis: the potential role of proton MR spectroscopy in defining the nature of disability.

PURPOSEWe determined the clinical utility of proton MR spectroscopy in defining the extent of disability in benign versus secondary-progressive multiple sclerosis (MS).METHODSThirty patients with clinically definite MS, including 16 patients with benign MS and 14 with secondary-progressive MS, and a group of 13 healthy volunteers were studied with combined stimulated-echo acquisition mode proton MR spectroscopy and MR imaging (all patients received contrast material).RESULTSAcute enhancing lesions of benign and secondary-progressive MS were characterized by a reduction in N-acetylaspartate (NAA)/choline and NAA/creatine and an increase in inositol compounds/creatine as compared with normal white matter. Such variations were also detected in chronic unenhancing lesions in patients with secondary-progressive MS, although they were not found in chronic unenhancing lesions in patients with benign MS. Chronic lesions of the two forms of the disease have significative differences in NAA and inositol signals.CONCLUSIONProton MR spectroscopy is able to show metabolic changes occurring in the white matter of patients with MS. Such changes differ according to the phase (acute versus chronic) and the clinical form (benign versus secondary-progressive) of the disease.