T1 mapping for head and neck Cancer patients undergoing Chemoradiotherapy: Feasibility of 3D stack of star imaging.

BACKGROUND: Measuring tissue oxygen concentration is crucial in understanding the pathophysiological process of hypoxia in head and neck cancer (HNC) and its significant role in cancer biology. This study aimed to determine the feasibility of T1 mapping using a variable flip angle (VFA) technique with stack of stars (SOS) trajectory sampling in HNC patients undergoing chemoradiotherapy (CRT). METHODS: To evaluate the ability of SOS acquisition to detect T1, a phantom study was conducted and compared to conventional Cartesian acquisition (CART). Additionally, four newly diagnosed patients were recruited and underwent two scans each at baseline and inter-treatment. The repeatability of SOS and CART acquisitions was assessed by comparing the T1 measurements of CSF from the baseline and intra-treatment MRI studies. The changes in ∆T1 of the tumors during air and oxygen inhalation between baseline and inter-treatment scans were also evaluated. RESULTS: Our study found that the 3D VFA SOS sequence was effective in reducing motion artifacts compared to the conventional VFA sequence with CART sampling and the same scan time, as demonstrated by the results from the phantom and patient studies. In terms of repeatability, no significant correlation was observed between the variability in ΔT1 measurements of CSF obtained from SOS T1 maps. The SOS ΔT1 measurements showed higher consistency, as evidenced by the ICC values ranging from 0.52 to 0.92. The ∆T1 measurements on the primary tumors increased after the first CRT (p<0.05) for all patients who showed a positive treatment response, except for one patient (0.05

Disparities in Provider Ordering Practices of Image-Guided Interventions and Surgery for Patients With Low Back Pain: A Cohort Study.

OBJECTIVE: To assess individual- and neighborhood-level sociodemographic factors associating with providers' ordering of nonpharmacologic treatments for patients with low back pain (LBP), specifically physical therapy, image-guided interventions, and lumbar surgery. METHODS: Our cohort included all patients diagnosed with LBP from 2000 to 2017 in a statewide database of all hospitals and ambulatory surgical facilities within Utah. We compared sociodemographic and clinical characteristics of (1) patients with LBP who received any treatment with those who received none and (2) patients with LBP who received invasive LBP treatments with those who only received noninvasive LBP treatments using the Student's t test, Wilcoxon's rank-sum tests, and Pearson's χ2 tests, as applicable, and two separate multivariate logistic regression models: (1) to determine whether sociodemographic characteristics were risk factors for receiving any LBP treatments and (2) risk factors for receiving invasive LBP treatments. RESULTS: Individuals in the most disadvantaged neighborhoods were less likely to receive any nonpharmacologic treatment orders (odds ratio [OR] 0.74 for most disadvantaged, P < .001) and received fewer invasive therapies (0.92, P = .018). Individual-level characteristics correlating with lower rates of treatment orders were female sex, Native Hawaiian or other Pacific Islander race (OR 0.50, P < .001), Hispanic ethnicity (OR 0.77, P < .001), single or unmarried status (OR 0.69, P < .001), and no insurance or self-pay (OR 0.07, P < .001). CONCLUSION: Neighborhood and individual sociodemographic variables associated with treatment orders for LBP with Area Deprivation Index, sex, race or ethnicity, insurance, and marital status associating with receipt of any treatment, as well as more invasive image-guided interventions and surgery.

Screening for Asymptomatic Osteonecrosis of the Hip in Systemic Lupus Erythematous: A Systematic Review and Meta-Analysis of MRI-Based Prevalence.

Objective. This paper aims to estimate asymptomatic hip osteonecrosis prevalence in SLE patients using MRI examination and to determine the prevalence among higher risk subpopulations. Materials and Methods. PubMed, Embase, Cochrane, and SCOPUS were searched from inception to May 9th, 2023. Studies on patients who were clinically diagnosed with systemic lupus erythematosus without reported symptoms attributable to hip osteonecrosis were included. Two independent reviewers extracted data and assessed the risk of bias. Data collected from each study include the study year, the number of hips screened, the number of hips with osteonecrosis, demographics, laboratory data, medications, follow-up time, radiological protocols, and MRI-based osteonecrosis detection and grading criteria. Results. Eleven eligible studies including 503 participants (15-35 years old; 74-100% female) with SLE were identified. Significant risk of bias was determined in one study. The overall prevalence of osteonecrosis of the hip was found to be 14% (184/1006 hip joints, 95% confidence interval: 7-22%, number needed to scan: 7.1). SLE patients who received corticosteroid treatment had a higher prevalence of asymptomatic hip osteonecrosis (18%) compared to non-corticosteroid users (0%, p-value < 0.01). Additionally, meta-regression results revealed that daily corticosteroid dose was associated with increased prevalence of asymptomatic osteonecrosis (0.5%/milligram, p-value < 0.01). Conclusions. The high prevalence of asymptomatic hip osteonecrosis in SLE patients raises concerns about the timeliness of interventions. The limitations of this study include a relatively low number of identified studies; and one study lacked full-text availability.

Evaluation of 3-dimensional stereotactic surface projection rendering of arterial spin labeling data in a clinical cohort.

BACKGROUND AND PURPOSE: To assess the feasibility of 3-dimensional stereotactic surface projection (3D-SSP) as applied to arterial spin labeling (ASL) in a clinical pilot study. METHODS: A retrospective sample of 10 consecutive patients who underwent ASL as part of a clinically indicated MR examination was collected during this pilot study. Five additional subjects with normal cerebral perfusion served as a control group. Following voxel-wise M0-correction, cerebral blood flow (CBF) quantification, and stereotactic anatomic standardization, voxel-wise CBF from an individual's ASL dataset was extracted to a set of predefined surface pixels (3D-SSP). A normal database was created from averaging the extracted CBF datasets of the control group. Patients' datasets were compared individually with the normal database by calculating a Z-score on a pixel-by-pixel basis and were displayed in 3D-SSP views for visual inspection. Independent, two-expert reader assessment, using a 3-point scale, compared standard quantitative CBF images to the 3D-SSP maps. RESULTS: Patterns and severities of regionally reduced CBF were identified, by both independent readers, in the 3D-SSP maps. Reader assessment demonstrated preference for 3D-SSP over traditionally displayed standard quantitative CBF images in three of four evaluated imaging metrics (p = .026, .031, and .013, respectively); 3D-SSP maps were never found to be inferior to the standard quantitative CBF images. CONCLUSIONS: Three-dimensional SSP maps are feasible in a clinical population and enable quantitative data extraction and localization of perfusion abnormalities by means of stereotactic coordinates in a condensed display. The proposed method is a promising approach for interpreting cerebrovascular pathophysiology.

The arterial input function: Spatial dependence within the imaging volume and its influence on 3D quantitative dynamic contrast-enhanced MRI for head and neck cancer.

PURPOSE: To evaluate the dependence of the arterial input function (AIF) on the imaging z-axis and its effect on 3D DCE MRI pharmacokinetic parameters as mediated by the SPGR signal equation and Extended Tofts-Kermode model. THEORY: For SPGR-based 3D DCE MRI acquisition of the head and neck, inflow effects within vessels violate the assumptions underlying the SPGR signal model. Errors in the SPGR-based AIF estimate propagate through the Extended Tofts-Kermode model to affect the output pharmacokinetic parameters. MATERIALS AND METHODS: 3D DCE-MRI data were acquired for six newly diagnosed HNC patients in a prospective single arm cohort study. AIF were selected within the carotid arteries at each z-axis location. A region of interest (ROI) was placed in normal paravertebral muscle and the Extended Tofts-Kermode model solved for each pixel within the ROI for each AIF. Results were compared to those obtained with a published population average AIF. RESULTS: Due to inflow effect, the AIF showed extreme variation in their temporal shapes. Ktrans was most sensitive to the initial bolus concentration and showed more variation over the muscle ROI with AIF taken from the upstream portion of the carotid. kep was less sensitive to the peak bolus concentration and showed less variation for AIF taken from the upstream portion of the carotid. CONCLUSION: Inflow effects may introduce an unknown bias to SPGR-based 3D DCE pharmacokinetic parameters. Variation in the computed parameters depends on the selected AIF location. In the context of high flow, measurements may be limited to relative rather than absolute quantitative parameters.

Surveillance Imaging with PET/CT and CT and/or MRI for Head and Neck Cancer and Mortality: A Population-based Study.

Background To the knowledge of the authors, no strong evidence supports surveillance imaging in patients with head and neck cancer (HNC). Purpose To investigate the association between surveillance imaging and mortality using a population-based study design with statewide cancer registry data, all-payer claims data, and health care facility data. Materials and Methods The retrospective population-based study identified patients with HNC diagnosed between January 2012 and December 2017. Current Procedural Terminology codes were used to search surveillance imaging procedures. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% CIs for mortality with adjustment for sex, ethnicity, age, health insurance status, cancer site, stage, and treatment. Results The study identified 1004 patients (mean age, 61 years ± 12 [SD]; 753 men), including 902 patients with squamous cell carcinoma (SCC) HNC and 102 patients with non-SCC. The effect of imaging on mortality among patients with SCC was not statistically significant when the entire sample was analyzed (HR, 0.76; 95% CI: 0.57, 1.02; P = .07). However, in stratified analyses by cancer stage, surveillance imaging was associated with lower mortality among patients with SCC for regionalized cancer stage (HR, 0.55; 95% CI: 0.36, 0.83; P = .005) and distant cancer stage (HR, 0.40; 95% CI: 0.19, 0.83; P = .01). Among patients with non-SCC, surveillance imaging was associated with lower mortality versus no surveillance imaging (HR, 0.19; 95% CI: 0.04, 0.94; P = .04). PET/CT was associated with lower mortality for patients with SCC (HR, 0.29; 95% CI: 0.09, 0.94; P = .04), and CT and/or MRI was associated with lower mortality for patients with non-SCC (HR, 0.11; 95% CI: 0.01, 0.94; P = .04). Conclusion Surveillance imaging was associated with lower mortality among patients with head and neck squamous cell carcinoma with regionalized or distant disease. The surveillance imaging protective association was observed up to 2 years after treatment completion. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Branstetter in this issue.

Direct cost analysis of rapid MRI in the emergency department evaluation of patients suspected of having acute ischemic stroke*.

BACKGROUND: Abbreviated "rapid MRI" protocols have become more common for the evaluation of acute ischemic stroke (AIS). Prior research has not evaluated the effect of rapid MRIs on cost or hospital length of stay in AIS patients. METHODS: We retrospectively identified AIS patients who presented within 6 h of acute neurologic symptom onset to an emergency department (ED) and activated a "brain attack" code. We included sequential patients from January 2012 to September 2015, before rapid MRI was available, who had CT perfusion (CTP) and compared them to patients from October 2015 to May 2018 who had a rapid MRI. We used inverse-probability-weighting (IPW) to balance the cohorts. The primary outcomes were direct cost to our healthcare system and total hospital length of stay (LOS). RESULTS: We included 408 brain attack activations (mean ± SD age 62.1 ± 17.6 years, 47.8% male): 257 in the CTP cohort and 151 in the MRI cohort. Discharge diagnosis was ischemic stroke in 193/408 (47.3%). After patient matching, we found significant reductions for the MRI cohort in total cost (-18.7%, 95% CI -35.0, -2.4, p = 0.02) and hospital LOS (-17.0%, 95% CI -31.2, -2.8, p = 0.02), with no difference in ED LOS (p = 0.74) as compared to the CTP cohort. CONCLUSION: Although these results are preliminary and hypothesis-generating, we found that the use of a rapid MRI protocol in emergency department brain attacks was associated with a 18.7% reduction in total direct cost and 17% reduction in hospital length of stay.

Anatomy of Neck Muscles, Spaces, and Lymph Nodes.

The following article details the muscular anatomy of the head and neck, including insertion, origin, action and innervation, organized by anatomic subunit and/or major action. This article also describes the spaces of the head and neck, including boundaties and contents. Finally, cervical lymph nodes are addressed according to anatomic location and lymphatic drainage.

Glymphatic MRI techniques in sleep and neurodegenerative diseases.

PURPOSE OF REVIEW: The purpose of this review article is to summarize the current in-vivo imaging techniques for the evaluation of the glymphatic function and discuss the factors influencing the glymphatic function and research directions in the future. RECENT FINDINGS: The glymphatic system allows the clearance of metabolic waste from the central nervous system (CNS). The glymphatic pathway has been investigated using intrathecal or intravenous injection of a gadolinium-based contrast agent (GBCA) on MRI, so-called glymphatic MRI. The glymphatic MRI indirectly visualizes the dynamic CSF flow and evaluated the glymphatic function in the animal and human models. Several clinical and preclinical studies using glymphatic MRI have confirmed that the glymphatic function is impaired in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and idiopathic normal pressure hydrocephalus. Furthermore, physiologic process such as sleep facilitates the glymphatic clearance, thus clearing accumulation of protein deposition, such as amyloid or tau, potentially delaying the progression of neurodegenerative diseases. SUMMARY: The glymphatic system plays a crucial role in clearing metabolic wastes in the brain. Glymphatic MR imaging using GBCA administration serves as a functional imaging tool to measure the glymphatic function and investigate various pathophysiologies of neurodegenerative diseases.

Deep-learning prediction of amyloid deposition from early-phase amyloid positron emission tomography imaging.

OBJECTIVE: While the use of biomarkers for the detection of early and preclinical Alzheimer's Disease has become essential, the need to wait for over an hour after injection to obtain sufficient image quality can be challenging for patients with suspected dementia and their caregivers. This study aimed to develop an image-based deep-learning technique to generate delayed uptake patterns of amyloid positron emission tomography (PET) images using only early-phase images obtained from 0-20 min after radiotracer injection. METHODS: We prepared pairs of early and delayed [11C]PiB dynamic images from 253 patients (cognitively normal n = 32, fronto-temporal dementia n = 39, mild cognitive impairment n = 19, Alzheimer's disease n = 163) as a training dataset. The neural network was trained with the early images as the input, and the output was the corresponding delayed image. A U-net convolutional neural network (CNN) and a conditional generative adversarial network (C-GAN) were used for the deep-learning architecture and the data augmentation methods, respectively. Then, an independent test data set consisting of early-phase amyloid PET images (n = 19) was used to generate corresponding delayed images using the trained network. Two nuclear medicine physicians interpreted the actual delayed images and predicted delayed images for amyloid positivity. In addition, the concordance of the actual delayed and predicted delayed images was assessed statistically. RESULTS: The concordance of amyloid positivity between the actual versus AI-predicted delayed images was 79%(κ = 0.60) and 79% (κ = 0.59) for each physician, respectively. In addition, the physicians' agreement rate was at 89% (κ = 0.79) when the same image was interpreted. And, the actual versus AI-predicted delayed images were not readily distinguishable (correct answer rate, 55% and 47% for each physician, respectively). The statistical comparison of the actual versus the predicted delated images indicated that the peak signal-to-noise ratio (PSNR) was 21.8 dB ± 2.2 dB, and the structural similarity index (SSIM) was 0.45 ± 0.04. CONCLUSION: This study demonstrates the feasibility of an image-based deep-learning framework to predict delayed patterns of Amyloid PET uptake using only the early phase images. This AI-based image generation method has the potential to reduce scan time for amyloid PET and increase the patient throughput, without sacrificing diagnostic accuracy for amyloid positivity.

Current Controversies in Radiology on Cost, Reimbursement, and Price Transparency: AJR Expert Panel Narrative Review.

Many believe that fundamental reform of the U.S. health care system is overdue and necessary given rising national health care expenditures, poor performance on key population health metrics, meaningful health disparities, concerns about potential financial toxicity of care, inadequate price transparency, pending insolvency of Medicare Part A, increasing commercial insurance premiums, and large uninsured and underinsured populations. The Medicare Payment Advisory Commission, an independent congressional agency, believes that part of this reform includes redistribution of reimbursements away from specialties such as radiology. Thus, despite an increase in the Medicare population and spending, Medicare payments for medical imaging have been decreasing for years. Further, the No Surprises Act, a federal law intended to curb the problem of surprise medical billing, was repurposed in federal rulemaking to reduce reimbursement from commercial payers to certain specialties, including radiology. In this article, we examine challenges facing the U.S. health care system, focusing on cost, reimbursement, and price transparency and the role of radiology in addressing such challenges. Medical imaging is a minor contributor to national health care expenditures but has an outsized impact on patient care. The radiology community should work together to reinforce the value of medical imaging and reduce inappropriate utilization of low-value care.

Health for All: A Report of the 2020 Association of American Medical Colleges Learn Serve Lead Meeting.

Learn Serve Lead (LSL) is the signature annual conference of the Association of American Medical Colleges (AAMC), which focuses on the most pressing issues facing American medical practice and education. Unsurprisingly, the recent AAMC LSL conference at the end of 2020 centered on the multifaceted impacts of the COVID-19 pandemic and racial inequity upon the medical community. At the LSL meeting, national leaders, practicing physicians from diverse specialties, and medical trainees discussed the impact of these challenges and ongoing strategies to overcome them. These efforts paralleled the AAMC mission areas of community collaborations, medical education, clinical care, and research. Additionally, this focus aligns with the ACR's core purpose: to serve patients and society by empowering members to advance the practice, science, and professions of radiological care. ACR is a member of the AAMC Council of Faculty and Academic Society and seeks to collaborate with other medical specialties to promote interdisciplinary collaboration, contribute to medical education, and voice the value of medical imaging for patient care. We summarize the major insights of this interdisciplinary conference and present tailored recommendations for applying these insights specifically within the radiology community. In addition, we review the parallels between the ACR and the AAMC strategic plans.

Imaging of Treated Thyroid and Parathyroid Disease.

The thyroid and parathyroid glands are endocrine structures located in the visceral space of the infrahyoid neck. Imaging plays a critical role in the evaluation of patients with thyroid cancer, both in the pre and posttreatment setting. Disorders of thyroid function, that is, hyperthyroidism and hypothyroidism, are also fairly common, although imaging utilization is less frequent with these conditions. Parathyroid dysfunction results in disordered calcium metabolism. Imaging is frequently applied in the preoperative assessment of these patients undergoing parathyroidectomy; however, routine imaging in the postoperative setting is uncommon. Parathyroid carcinoma is rare; however, imaging may be used in the pre and posttreatment setting.