Diagnostic Magnetic Resonance Imaging Research Articles

Left-Right Intensity Asymmetries Vary Depending on Scanner Model for FLAIR and T1 Weighted MRI Images.

BackgroundLocalized regions of left–right image intensity asymmetry (LRIA) were incidentally observed on T2‐weighted (T2‐w) and T1‐weighted (T1‐w) diagnostic magnetic resonance imaging (MRI) images. Suspicion of herpes encephalitis resulted in unnecessary follow‐up imaging. A nonbiological imaging artifact that can lead to diagnostic uncertainty was identified.PurposeTo investigate whether systematic LRIA exist for a range of scanner models and to determine if LRIA can introduce diagnostic uncertainty.Study TypeA retrospective study using the Alzheimer's Disease Neuroimaging Initiative (ADNI) data base.SubjectsOne thousand seven hundred fifty‐three (median age: 72, males/females: 878/875) unique participants with longitudinal data were included.Field Strength3T.SequencesT1‐w three‐dimensional inversion‐recovery spoiled gradient‐echo (IR‐SPGR) or magnetization‐prepared rapid gradient‐echo (MP‐RAGE) and T2‐w fluid‐attenuated inversion recovery (FLAIR) long tau fast spin echo inversion recovery (LT‐FSE‐IR). Only General Electric, Philips, and Siemens' product sequences were used.AssessmentLRIA was calculated as the left–right percent difference with respect to the mean intensity from automated anatomical atlas segmented regions. Three neuroradiologists with 37 (**), 32 (**), and 3 (**) years of experience rated the clinical impact of 30 T2‐w three‐dimensional FLAIR exams with LRIA to determine the diagnostic uncertainty. Statistical comparisons between retrospective intensity normalized T1m and original T1‐w images were made.Statistical TestsFor each image type, a linear mixed effects model was fit using LRIA scores from all scanners, regions, and participants as the outcome and age and sex as predictors. Statistical significance was defined as having a P‐value <0.05.ResultsLRIA scores were significantly different from zero on most scanners. All clinicians were uncertain or recommended definite diagnostic follow‐up in 62.5% of cases with LRIA >10%. Individuals with acute brain pathology or focal neurologic deficits are not enrolled in ADNI; therefore, focal signal abnormalities were considered false positives.Data ConclusionLRIA is system specific, systematic, creates diagnostic uncertainty, and impacts IR‐SPGR, MP‐RAGE, and LT‐FSE‐IR product sequences.Level of Evidence: 2Technical Efficacy Stage: 3

Automatic segmentation of high-risk clinical target volume for tandem-and-ovoids brachytherapy patients using an asymmetric dual-path convolutional neural network.

Preimplant diagnostic magnetic resonance imaging is the gold standard for image-guided tandem-and-ovoids (T&O) brachytherapy for cervical cancer. However, high dose rate brachytherapy planning is typically done on postimplant CT-based high-risk clinical target volume (HR-CTVCT ) because the transfer of preimplant Magnetic resonance (MR)-based HR-CTV (HR-CTVMR ) to the postimplant planning CT is difficult due to anatomical changes caused by applicator insertion, vaginal packing, and the filling status of the bladder and rectum. This study aims to train a dual-path convolutional neural network (CNN) for automatic segmentation of HR-CTVCT on postimplant planning CT with guidance from preimplant diagnostic MR. Preimplant T2-weighted MR and postimplant CT images for 65 (48 for training, eight for validation, and nine for testing) patients were retrospectively solicited from our institutional database. MR was aligned to the corresponding CT using rigid registration. HR-CTVCT and HR-CTVMR were manually contoured on CT and MR by an experienced radiation oncologist. All images were then resampled to a spatial resolution of 0.5× 0.5 × 1.25mm. A dual-path 3D asymmetric CNN architecture with two encoding paths was built to extract CT and MR image features. The MR was masked by HR-CTVMR contour while the entire CT volume was included. The network put an asymmetric weighting of 18:6 for CT: MR. Voxel-based dice similarity coefficient (DSCV ), sensitivity, precision, and 95% Hausdorff distance (95-HD) were used to evaluate model performance. Cross-validation was performed to assess model stability. The study cohort was divided into a small tumor group(<20 cc), medium tumor group (20-40cc), and large tumor group(>40cc) based on the HR-CTVCT for model evaluation. Single-path CNN models were trained with the same parameters as those in dual-path models. For this patient cohort, the dual-path CNN model improved each of our objective findings, including DSCV , sensitivity, and precision, with an average improvement of 8%, 7%, and 12%, respectively. The 95-HD was improved by an average of 1.65mm compared to the single-path model with only CT images as input. In addition, the area under the curve for different networks was 0.86 (dual-path with CT and MR) and 0.80 (single-path with CT), respectively. The dual-path CNN model with asymmetric weighting achieved the best performance with DSCV of 0.65 ± 0.03 (0.61-0.70), 0.79 ± 0.02 (0.74-0.85), and 0.75 ± 0.04 (0.68-0.79) for small, medium, and large group. 95-HD were 7.34 (5.35-10.45) mm, 5.48 (3.21-8.43) mm, and 6.21 (5.34-9.32) mm for the three size groups, respectively. An asymmetric CNN model with two encoding paths from preimplant MR (masked by HR-CTVMR ) and postimplant CT images was successfully developed for automatic segmentation of HR-CTVCT for T&O brachytherapy patients.

Cost-Effectiveness of Prostate Cancer Detection in Biopsy-Naïve Men: Ultrasound Shear Wave Elastography vs. Multiparametric Diagnostic Magnetic Resonance Imaging.

This exploratory study investigates the cost-effectiveness of ultrasound shear wave elastography (SWE) imaging in comparison to pre-biopsy multiparametric magnetic resonance imaging (mpMRI) in men with suspected prostate cancer. This research is motivated by the early evidence of the good performance of SWE in distinguishing cancerous from benign prostate tissues. We used a decision analysis model representing the care-pathways of men referred with a high prostate specific antigen (PSA) and/or abnormal digital rectal examination (DRE) in a UK setting from the payer’s perspective with results reported in 2016 GBP. We then appraised the cost-effectiveness of a novel approach based on SWE compared to the more conventional and widely practiced mpMRI-based approaches using data reported in the literature. Deterministic and probabilistic sensitivity analyses were used to address uncertainty regarding the parameter values utilised. Our exploratory results implied that SWE approach yielded an additional quality-adjusted life year (QALY) at the cost of GBP 10,048 compared to the standard mpMRI-based approach in the UK. This is lower than the official willingness to pay threshold of GBP 20,000 (the UK healthcare system guidelines) and is therefore a suitable replacement for the current practice. Sensitivity analyses confirmed the robustness of our results.

Cross-sectional diagnostic imaging in the InEK benchmark : An opportunity for radiology

HintergrundAnhand der vom Institut für das Entgeltsystem im Krankenhaus (InEK) kalkulierten Fallpauschalen ist ein Vergleich der eigenen Leistungsdaten gegenüber allen nach der DRG („diagnosis-related groups“, diagnosebezogene Gruppen) abrechnenden Kliniken in Deutschland möglich. Ziel der vorliegenden Arbeit ist es, Über- oder Unterschreitungen von CT- oder MRT-Untersuchungen im Vergleich mit den InEK-Daten zu ermitteln und mögliche Verbesserungspotenziale zu erschließen.MethodikDie InEK-Kalkulationsdaten für 2021 wurden zur Bildung von Vergleichskennzahlen der CT- und MRT-Diagnostik auf DRG-Ebene herangezogen. Auf Fallebene wurden Daten eines universitären Maximalversorgers auf Gesamthaus‑, Klinik‑, DRG- und Hauptdiagnosen-Ebene gegenübergestellt.ErgebnisAuf Gesamthausebene zeigt sich eine Überschreitung der MRTs um 1025 und der CTs um 371 gegenüber InEK. Die Analyse nach Fachabteilungen ergab am Beispiel der Neurologie eine Überschreibung der MRTs gegenüber InEK um 489 sowie eine Unterschreitung der CTs um -620. Der Benchmark der DRGs zeigte in beiden Untersuchungsmodalitäten insbesondere die DRG B70B als Treiber der Abweichungen (MRT + 42,7; CT − 273). Die identifizierten Abweichungen lassen sich auf Hauptdiagnosen-Ebene weiter herunterbrechen.DiskussionDas Bewusstsein über eine überdurchschnittliche Schnittbilddiagnostik kann einen wichtigen Anstoß zur Weiterentwicklung der Behandlungspfade einer Klinik bilden. Die Methodik des InEK-Benchmarks ist für jedes Krankenhaus anwendbar und identifiziert valide bereits erbrachte Leistungen und Prozesse mit einem Verbesserungspotenzial. Die Prüfung beeinflussender Faktoren sowie die Bewertung durch Mediziner und Kaufleute bildet die Voraussetzung für Akzeptanz und Erfolg der daraus generierten Maßnahmen.

Brain stereotactic radiosurgery using MR-guided online adaptive planning for daily setup variation: An end-to-end test.

Online magnetic resonance (MR)‐guided radiotherapy is expected to benefit brain stereotactic radiosurgery (SRS) due to superior soft tissue contrast and capability of daily adaptive planning. The purpose of this study was to investigate daily adaptive plan quality with setup variations and to perform an end‐to‐end test for brain SRS with multiple metastases treated with a 1.5‐Tesla MR‐Linac (MRL). The RTsafe PseudoPatient Prime brain phantom was used with a delineation insert that includes two predefined structures mimicking gadolinium contrast‐enhanced brain lesions. Daily adaptive plans were generated using six preset and six random setup variations. Two adaptive plans per daily MR image were generated using the adapt‐to‐position (ATP) and adapt‐to‐shape (ATS) workflows. An adaptive patient plan was generated on a diagnostic MR image with simulated translational and rotational daily setup variation and was compared with the reference plan. All adaptive plans were compared with the reference plan using the target coverage, Paddick conformity index, gradient index (GI), Brain V12 or V20, optimization time and total monitor units. Target doses were measured as an end‐to‐end test with two ionization chambers inserted into the phantom. With preset translational variations, V12 from the ATS plan was 17% lower than that of the ATP plan. With a larger daily setup variation, GI and V12 of the ATS plan were 10% and 16% lower than those of the ATP plan, respectively. Compared to the ATP plans, the plan quality index of the ATS plans was more consistent with the reference plan, and within 5% in both phantom and patient plans. The differences between the measured and planned target doses were within 1% for both treatment workflows. Treating brain SRS using an MRL is feasible and could achieve satisfactory dosimetric goals. Setup uncertainties could be accounted for using online plan adaptation. The ATS workflow achieved better dosimetric results than the ATP workflow at the cost of longer optimization time.

A longer duration from injury to surgery is associated with preoperative deterioration of an isolated meniscal tear in patients aged 40 years or older.

To evaluate the preoperative deterioration of an isolated meniscal tear in patients aged 40 years or older, and whether time from injury to surgery is associated with worsening of a meniscal tear. Patients aged 40 years or older who underwent arthroscopic surgery for isolated meniscal tear between 2014 and 2019 were retrospectively reviewed. The diagnostic magnetic resonance imaging (MRI) findings and arthroscopic findings were compared to evaluate the deterioration of meniscal tears. Predictors of the development of meniscal tears; patient demographic factors, duration from injury to surgery (injury to MRI and MRI to surgery), and image findings were assessed. A total of 58 patients (58 knees) were included (mean age, 55.9 ± 8.5 years; male/female, 31/27). An isolated meniscal tear deteriorated in 28 (48.3%). Compared patients with and without deteriorated meniscal tear, significant differences were found in the MRI grade of meniscal tear (p = 0.03), duration from injury to MRI (164.2 ± 167.9 vs 45.2 ± 48.7 days, p < 0.001), and from MRI to surgery (148.8 ± 91.1 vs 67.6 ± 56.7 days, p < 0.001). A multivariate regression analysis showed that the duration from injury to MRI (odds ratio [OR], 1.03; p < 0.001) and from MRI to surgery (OR, 1.02; p < 0.001) were independent predictors. Approximately 50% of isolated meniscal tears deteriorated preoperatively in patients aged 40 years or older. The duration from injury to surgery was an independent predictor of worsening of an isolated meniscal tear.

Overcoming pubic arch interference in prostate brachytherapy using steerable needles.

A proportion of patients are not directly eligible for prostate brachytherapy (BT) due to pubic arch interference (PAI). Constraints in positioning sources behind the pubic arch due to linear, horizontal needle paths, may hamper effective irradiation of the target volume. This work evaluated the effect of prostate volume (Vp) and patient posture change on the amount of PAI, and demonstrated that steerable needles may broaden the inclusion criteria for patients with enlarged prostates and observed PAI. Twenty-seven patients (Vp > 60 cc) were included in this study. Access obstruction to the prostate was evaluated using diagnostic magnetic resonance imaging (MRI) scans, after six upward rotations of the pelvis and the prostate in 5 degree steps, to indicate the effect of patient posture change from supine to lithotomy position. For patients with PAI, we evaluated if the steerable needle could access the obstructed volume of the prostate. The data showed no clear relation between Vp and PAI. In 23 of the 27 patients, in which PAI was observed, 14 showed obstruction of the prostate of ≥ 10 mm in the supine position (mean PAI ± standard deviation: 15.2 ±3.8 mm). Anatomical rotation reduced PAI by 4.8 mm after every 10 degrees of upward rotation, still resulting in obstructions of 8.1 ±2.4 mm in 10 of the 14 cases after 15 degree rotation. The steerable needle enabled access to all the required coordinates of the prostate. The ability to steer along curved paths enables prostate BT in patients with enlarged prostates and PAI, and reduces the change of needing to abandon treatment.

The Use of Magnetic Resonance Imaging in Diagnostics of Radix Paramolaris: A Case Report

Background and Objectives: This case report aims to present a rare morphological variation of Radix Paramolaris (RP) diagnosed using Magnetic Resonance Imaging (MRI) to discuss its morphological associations and possible implications on dental treatment. Radix paramolaris is a buccally located supernumerary root of the permanent mandibular molars. It is very rare in the European population, with a prevalence below 4%. Case Presentation: A 7-year-old boy with severe Class II malocclusion is presented. The first phase of orthodontic treatment consisted of therapy with a removable activator appliance. Before the second phase of treatment, unilateral radix paramolaris on the second right permanent mandibular molar was discovered. Results: Supernumerary root was diagnosed using a 3T whole-body MRI system. This case confirmed the association between supernumerary roots and increased buccal crown cusps in a mandibular molar. Furthermore, it demonstrated the effectiveness of non-invasive MRI as a complementary diagnostic tool, offering clear advantages in diagnosing rare morphological variations such as supernumerary roots. Unlike conventional radiography, MRI is able to distinguish the soft tissues, including the dental pulp, and does not emit ionizing radiation. Conclusion: To diagnose a supernumerary root and the state of its pulpal tissue, a precise radiographic and clinical examination is required since awareness of exact root morphology can be of paramount importance in clinical decision-making for several dental procedures.

Lateral Supracerebellar Infratentorial Approach for Superior Oblique Myokymia: A Case Series.

Few reports have shown that superior oblique myokymia (SOM) may result from vascular compression of the trochlear nerve and may be curable using microvascular decompression (MVD). To report the clinical characteristics and surgical treatment of 2 cases of SOM and provide a review of the related literature. Two patients with SOM were treated using MVD with the lateral supracerebellar infratentorial approach. The patients underwent diagnostic magnetic resonance imaging and three-dimensional fusion imaging preoperatively. A lateral suboccipital craniotomy was performed in the park-bench position. The trochlear nerve and branches of the superior cerebellar artery were confirmed after opening the cerebellomesencephalic fissure over the tentorial surface of the cerebellum. The vessel, which compressed the root exit zone of the trochlear nerve, was transposed far from the nerve and attached to the surface of the midbrain using Teflon felt and fibrin glue. The first case showed compression on both the ventral and rostral sides of the trochlear nerve root exit zone, and the second showed compression only on the ventral side. Large bridging veins on the tentorial surface of the cerebellum complicated the approach in the second case. Postoperatively, both patients had immediate and complete resolution of symptoms without recurrence at the 24-mo and 17-mo follow-ups, respectively. Five previous reports described the complete resolution of SOM after MVD. A presentation of an intermittent fluttering ocular sensation should prompt magnetic resonance imaging for ipsilateral trochlear nerve compression. The lateral supracerebellar infratentorial approach allows safe and efficacious MVD for SOM.

Magnetic resonance in patients with implanted electronic cardiac devices in light of the 2021 ESC cardiac pacing and cardiac resynchronization therapy guidelines

For over a decade, implantable electrotherapy devices have been available which allow — under certain conditions — diagnostic magnetic resonance imaging (MRI) tests to be performed. Detailed recommendations for the performance of these tests have been published in the latest guidelines by the European Society of Cardio­logy (ESC). The latest guidelines, compared to the 2013 recommendations, changed the recommendation class for MRI examinations. They strongly emphasised that the presence of a typical pacing system, cardioverter-defibrillator or resynchronization system, does not constitute a contraindication to MRI diagnostics. The guidelines also indicate that under certain conditions, such tests are safe and should be performed. This article pre­sents detailed recommendations of the qualifications required for an MRI and the programming devices recommended by the ESC.

Optic pathway glioma and the sex association in neurofibromatosis type 1: a single-center study

BackgroundLow-grade optic pathway glioma (OPG) develops in 15–20% of children with neurofibromatosis type 1 (NF1). OPGs are symptomatic in 30–50% and one-third of these require treatment. A few studies have suggested female sex as a risk factor for visual impairment associated with NF1-OPG. This descriptive study investigated the correlation between NF1-OPG growth, sex and visual impairment.MethodWe based our cross-sectional study on a systematic, retrospective data collection in a NF1 cohort of children and adolescents below 21 years of age followed at Center for Rare Diseases, Aarhus University Hospital, Denmark. For each patient with OPG a medical chart review was performed including demographics, ophthalmological examinations and magnetic resonance imaging (MRI) of OPG.ResultsOf 176 patients with NF1 (85 females, 91 males), we identified 21 patients with OPG (11.9%) with a preponderance of females, p = 0.184. Eight females (62%) and one male (13%) had visual impairment at the last ophthalmological evaluation. Five out of 21 children with OPG (24%) underwent diagnostic MRI because of clinical findings at the ophthalmological screening. Nine children (43%) had symptoms suggestive of OPG and seven (33%) experienced no OPG-related symptoms before the diagnostic MRI. Of eight children diagnosed with OPG ≤ two years of age, one had visual impairment. Of 13 children diagnosed > two years of age, eight had visual impairment; in each group, four of the children were treated with chemotherapy. The study suggested no correlation between NF1-OPG growth and sex.ConclusionOur data suggest sex as a risk factor for visual impairment, while an OPG diagnose ≤ two years of age was a protective factor for visual impairment. Females with NF1-OPG had a higher prevalence of visual impairment outcome compared to males. Interestingly, our data also suggest a better response to treatment in children with OPG diagnosed ≤ two years of age compared to older children. The findings in our study suggest sex as a potential prognostic factor for visual impairment.

Sphenochoanal polyp

Sphenochoanal polyp are rare tumours arising from sphenoid sinus. The main presenting complain is gradually progressing nasal obstruction. Sphenochoanal polyp mimics antrochoanal polyp clinically. To differentiate it from antrochoanal polyp, diagnostic nasal endoscopy, computer tomography and magnetic resonance imaging of the paranasal sinuses are the investigation of choice. Functional endoscopic sinus surgery is the line of treatment.: A 33years old female presented with right nasal obstruction since 2 years. On Diagnostic nasal endoscopy polypoidal mass was seen partially obliterating the right nasal cavity not arising from middle meatus. CT scan showed polypoidal mass obliterating the nasal cavity, choana and Sphenoid sinus. It was completely excised by functional endoscopic surgery.We present this rare case to highlight the use of diagnostic nasal endoscopy and Computed Tomography in the diagnosis and treatment of Sphenochoanal polyps

Need for and predictability of magnetic resonance imaging examinations in patients with implanted neurostimulators

HintergrundBei steigender Zahl von Magnetresonanztomographie(MRT)-Untersuchungen in der deutschen Gesamtbevölkerung gibt es keine Daten zum Untersuchungsbedarf von Patienten mit implantiertem Neurostimulator in Deutschland. Publizierte Daten aus den USA legen einen hohen Bedarf nahe. Die eingeschränkte MRT-Zulassung der Implantate ist in der täglichen Praxis ein häufiges Problem.ZielIm Fokus steht der MRT-Bedarf dieser Schmerzpatienten und die Vorhersagbarkeit zum Zeitpunkt der Implantation.Material und MethodenEs erfolgte eine retrospektive Auswertung der Datenbank unseres Klinikinformationssystems. Gesucht wurden alle im Zeitraum November 2011 bis März 2019 in unserem Klinikum angeforderten MRT-Untersuchungen für Patienten mit implantiertem Neurostimulator. Zudem erfolgte ein Abgleich mit den im gleichen Zeitraum durchgeführten Implantationen derartiger Stimulationssysteme.ErgebnisseEs konnten 171 durchgeführte MRT-Untersuchungen und 22 Anforderungen ohne nachfolgende Untersuchung ausgewertet werden. Bei 83 von 294 Patienten, die in unserem Zentrum mit implantierten Neurostimulatoren versorgt wurden, erfolgte mindestens eine MRT-Untersuchung in unserem Klinikum. Wir beobachten eine stetig steigende Nachfrage. In 111 von 171 durchgeführten Untersuchungen (65 %) bestand kein Zusammenhang zwischen der zur Implantation führenden Indikation und der Indikation für die MRT. Eine Vorhersagbarkeit konnte nur bei 43 von 193 MRT-Anforderungen (22 %) unterstellt werden.DiskussionPatienten mit implantiertem Neurostimulator haben auch in Deutschland einen hohen Bedarf an MRT-Diagnostik, welcher zum Zeitpunkt der Implantation nicht vorhersagbar ist. Daher sollten ausschließlich MRT-taugliche Systeme implantiert werden. Die Industrie ist aufgefordert, die Implantate und deren Zulassungen an den Bedarf anzupassen.

A comparison of the efficiency of diagnostic ultrasound and magnetic resonance imaging of cervical lymph nodes in papillary thyroid carcinoma.

To compare and evaluate diagnostic capabilities of preoperative ultrasonography (US) and magnetic resonance imaging (MRI) in the cervical lymph nodes of patients with papillary thyroid cancer. A retrospective dataset involving 156 patients who had undergone thyroidectomy and preoperative US and MRI was assembled. Among these, 69 had cervical lymph node metastasis and 87 did not. At least four radiologists unilaterally and spontaneously investigated the US and MRI attributes of the cervical lymph nodes. The efficiency of diagnostic imaging for cervical lymph nodes, including their true-positive rate or sensitivity, true-negative rate or specificity, positive predictive value, negative predictive value, and predictive accuracy were analysed and assessed. In the assessment of cervical lymph node metastases of papillary thyroid cancer, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of diagnostic US vs. MRI were 58.0% vs. 79.7%, 69.0% vs. 83.9%, 59.7% vs. 79.7%, 67.4% vs. 83.9%, and 64.1% vs. 82.1%, respectively. The accuracy consistency of the two imaging modalities was 83.5%. MRI is more effective than US in diagnosing and assessing cervical lymph node metastases of papillary thyroid cancer.

Failure mode and effect analysis for linear accelerator-based paraspinal stereotactic body radiotherapy.

IntroductionParaspinal stereotactic body radiotherapy (SBRT) involves risks of severe complications. We evaluated the safety of the paraspinal SBRT program in a large academic hospital by applying failure modes and effects analysis.MethodsThe analysis was conducted by a multidisciplinary committee (two therapists, one dosimetrist, four physicists, and two radiation oncologists). The paraspinal SBRT workflow was segmented into four phases (simulation, treatment planning, delivery, and machine quality assurance (QA)). Each phase was further divided into a sequence of sub‐processes. Potential failure modes (PFM) were identified from each subprocess and scored in terms of the frequency of occurrence, severity and detectability, and a risk priority number (RPN). High‐risk PFMs were identified based on RPN and were studied for root causes using fault tree analysis.ResultsOur paraspinal SBRT process was characterized by eight simulations, 11 treatment planning, nine delivery, and two machine QA sub‐processes. There were 18, 29, 19, and eight PFMs identified from simulation, planning, treatment, and machine QA, respectively. The median RPN of the PFMs was 62.9 for simulation, 68.3 for planning, 52.9 for delivery, and 22.0 for machine QA. The three PFMs with the highest RPN were: previous radiotherapy outside the institution is not accurately evaluated (RPN: 293.3), incorrect registration between diagnostic magnetic resonance imaging and simulation computed tomography causing incorrect contours (273.0), and undetected patient movement before ExacTrac baseline (217.8). Remedies to the high RPN failures were implemented, including staff education, standardized magnetic resonance imaging acquisition parameters, and an image fusion process, and additional QA on beam steering.ConclusionsA paraspinal SBRT workflow in a large clinic was evaluated using a multidisciplinary and systematic risk analysis, which led to feasible solutions to key root causes. Treatment planning was a major source of PFMs that systematically affect the safety and quality of treatments. Accurate evaluation of external treatment records remains a challenge.

Diffusional kurtosis imaging as a possible prognostic marker of cervical incomplete spinal cord injury outcome: a prospective pilot study.

Spinal cord injury (SCI) is associated with substantial chronic morbidity and mortality. Routine imaging techniques such as T1- and T2-weighted magnetic resonance imaging (MRI) are not effective in predicting neurological deficiency grade or outcome. Diffusional kurtosis imaging (DKI) is an MR imaging technique that provides microstructural information about biological tissue. There are no longitudinal prospective studies assessing DKI metrics in acute traumatic SCI. Therefore, the purpose of this study was to establish a DKI protocol for acute SCI and correlate the DKI metrics to the functional neurological outcome of the patients. Eight consecutive SCI patients referred to our institution with cervical SCI were included in the study. An acute diagnostic MRI scan was supplemented with a novel fast, mean kurtosis DKI protocol, which describes the average deviation from Gaussian diffusional along nine different directions. Mean kurtosis values were measured at the injury site and normalized to the mean kurtosis values of a non-injured site. At discharge form specialized rehabilitation, patients were evaluated using the Spinal Cord Independence Measure-III (SCIM-III). The DKI metrics and SCIM-III were analysed using Spearman's rank correlation. This pilot study found a significant correlation between decreasing mean kurtosis values at the injury site of the spinal cord and higher grade of disability measured by the SCIM-III (p = 0.002). This pilot study found that DKI may be a valuable tool as a prognostic marker in the acute phase of SCI.

Clinical Complete Response in Patients With Rectal Adenocarcinoma Treated With Short-Course Radiation Therapy and Nonoperative Management

This study aimed to determine the clinical efficacy and safety of nonoperative management (NOM) for patients with rectal cancer with a clinical complete response (cCR) after short-course radiation therapy and consolidation chemotherapy. Patients with stage I-III rectal adenocarcinoma underwent short-course radiation therapy followed by consolidation chemotherapy between January 2018 and May 2019 (n = 90). Clinical response was assessed by digital rectal examination, pelvic magnetic resonance imaging, and endoscopy. Of the patients with an evaluable initial response, those with a cCR (n = 43) underwent NOM, and those with a non-cCR (n = 43) underwent surgery. The clinical endpoints included local regrowth-free survival, regional control, distant metastasis-free survival, disease-free survival, and overall survival. Compared with patients with an initial cCR, patients with initial non-cCR had more advanced T and N stage (P = .05), larger primary tumors (P = .002), and more circumferential resection margin involvement on diagnostic magnetic resonance imaging (P < .001). With a median follow-up of 30.1 months, the persistent cCR rate was 79% (30 of 38 patients) in the NOM cohort. The 2-year local regrowth-free survival was 81% (95% confidence interval [CI], 70%-94%) in the initial cCR group, and all patients with local regrowth were successfully salvaged. Compared with those with a non-cCR, patients with a cCR had improved 2-year regional control (98% [95% CI, 93%-100%] vs 85% [95% CI, 74%-97%], P = .02), distant metastasis-free survival (100% [95% CI, 100%-100%] vs 80% [95% CI, 69%-94%], P < .01), disease-free survival (98% [95% CI, 93%-100%] vs 71% [95% CI, 59%-87%], P < .01), and overall survival (100% [95% CI, 100%-100%] vs 88% [95% CI, 79%-98%], P = .02). No late grade 3+ gastrointestinal or genitourinary toxicities were observed in the patients who underwent continued NOM. Short-course radiation therapy followed by consolidation chemotherapy may be a feasible organ preservation strategy in rectal cancer. Additional prospective studies are necessary to evaluate the safety and efficacy of this approach.

Understanding the Effect of the Electron Spin Relaxation on the Relaxivities of Mn(II) Complexes with Triazacyclononane Derivatives.

Investigating the relaxation of water 1H nuclei induced by paramagnetic Mn(II) complexes is important to understand the mechanisms that control the efficiency of contrast agents used in diagnostic magnetic resonance imaging (MRI). Herein, a series of potentially hexadentate triazacyclononane (TACN) derivatives containing different pendant arms were designed to explore the relaxation of the electron spin in the corresponding Mn(II) complexes by using a combination of 1H NMR relaxometry and theoretical calculations. These ligands include 1,4,7-triazacyclononane-1,4,7-triacetic acid (H3NOTA) and three derivatives in which an acetate group is replaced by sulfonamide (H3NO2ASAm), amide (H2NO2AM), or pyridyl (H2NO2APy) pendants. The analogue of H3NOTA containing three propionate pendant arms (H3NOTPrA) was also investigated. The X-ray structure of the derivative containing two acetate groups and a sulfonamide pendant arm [Mn(NO2ASAm)]− evidenced six-coordination of the ligand to the metal ion, with the coordination polyhedron being close to a trigonal prism. The relaxivities of all complexes at 20 MHz and 25 °C (1.1–1.3 mM–1 s–1) are typical of systems that lack water molecules coordinated to the metal ion. The nuclear magnetic relaxation profiles evidence significant differences in the relaxivities of the complexes at low fields (<1 MHz), which are associated with different spin relaxation rates. The zero field splitting (ZFS) parameters calculated by using DFT and CASSCF methods show that electronic relaxation is relatively insensitive to the nature of the donor atoms. However, the twist angle of the two tripodal faces that delineate the coordination polyhedron, defined by the N atoms of the TACN unit (lower face) and the donor atoms of the pendant arms (upper face), has an important effect in the ZFS parameters. A twist angle close to the ideal value for an octahedral coordination (60°), such as that in [Mn(NOTPrA)]−, leads to a small ZFS energy, whereas this value increases as the coordination polyhedron approaches to a trigonal prism.

MRI Diagnostics of Intracranial hypotension Syndrome on the Example of Clinical Observation

Intracranial hypotension is a clinical and radiological syndrome, manifested by a decrease in the volume or pressure of the cerebrospinal fluid caused by various reasons, one of the main clinical manifestations of which are orthostatic headaches. The gold standard in the radiation diagnosis of this condition is magnetic resonance imaging (MRI). Increasing the awareness of radiologists about this pathology, its manifestations on MRI, will allow more often to diagnose this syndrome and choose the tactics of further treatment. This publication presents its own clinical observation — a patient with intracranial hypotension syndrome, on his example, MR and clinical manifestations are considered, and some data on the etiology and pathogenetic mechanisms of the described pathological process are also given.

Outcomes of dexmedetomidine sedation for drug-induced sleep ciné magnetic resonance imaging studies in pediatric obstructive sleep apnea patients.

Dexmedetomidine is utilized as a sedative agent for drug-induced sleep cine magnetic resonance imaging studies due to its ability to mimic natural sleep and lack of respiratory depressant effects. The outcomes of dexmedetomidine sedation such as respiratory complications and unplanned admissions in obstructive sleep apnea patients undergoing these studies are currently unknown. To describe the outcomes of dexmedetomidine sedation for outpatient drug-induced sleep magnetic resonance imaging in pediatric patients with obstructive sleep apnea. This is a retrospective chart review conducted in pediatric patients with obstructive sleep apnea undergoing outpatient drug-induced sleep ciné magnetic resonance imaging studies with dexmedetomidine sedation. Demographics, comorbidities, polysomnography study results, vital signs, respiratory complications, airway interventions, successful completion of the scan, and unplanned hospital admissions were measured. We analyzed 337 patients aged 2-18years (median age of 11years). The imaging was completed with dexmedetomidine as the sole sedative agent in 61% (N=207) patients. Ketamine was administered as additional sedative agent in 36% (N=122) of the patients. There was no difference in sedation-related adverse events and respiratory complications with regard to the severity of sleep apnea with the exception of mild desaturation episodes (SpO2 85%-90%). Patients who received additional sedative agents had significantly longer recovery room stay (71.5 [44] vs 55 [39] minutes; 95% CI of difference [9 to 23min], p<0.001) and total periprocedural stay (164.5 [52] vs 138 [64] minutes; 95% CI of difference [17 to 35min], p<.001). Dexmedetomidine alone or along with ketamine provided acceptable sedation in majority of the patients with obstructive sleep apnea undergoing outpatient diagnostic sleep magnetic resonance imaging studies without significant respiratory adverse events regardless of the severity of sleep apnea. Sedation failure and unplanned admissions are rare, and routine planned admission may not be required for this patient population.