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This study aims to introduce national diagnostic reference levels (NDRLs) for adult hybrid single photon emission computed tomography (SPECT-CT) in nuclear medicine (NM) departments in the Kingdom of Saudi Arabia. The administered activity (AA) of radiopharmaceuticals, volume-weighted computed tomography dose index (CTDIvol) and dose length product (DLP) for ten hybrid SPECT/CT examinations were collected and analysed for one year. The median of AA, CTDIvoland DLP for each dose quantity was derived and the suggested national DRLs were determined based on the 75thpercentile for all identified SPECT-CT examinations. A comparison of the defined adult NDRLs in Saudi Arabia with the published data of other countries was performed. Although there are no significant variations of the proposed NDRL of AA between countries, the proposed NDRLs of the integrated CT metrics exceed the published data in most procedures. NM departments are urged to consider optimisation for both image quality and radiation protection.
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Niveles de Referencia para Diagnóstico , Tomografía Computarizada de Emisión de Fotón Único , Adulto , Humanos , Dosis de Radiación , Arabia Saudita , Tomografía Computarizada por Rayos X/métodos , Valores de ReferenciaRESUMEN
OBJECTIVES: Simultaneous intracranial EEG and functional MRI (icEEG-fMRI) recordings in humans, whereby EEG is recorded from electrodes implanted inside the cranium during fMRI scanning, were made possible following safety studies on test phantoms and our specification of a rigorous data acquisition protocol. In parallel with this work, other investigations in our laboratory revealed the damage caused by the EEG electrode implantation procedure at the cellular level. The purpose of this report is to further explore the safety of performing MRI, including simultaneous icEEG-fMRI data acquisitions, in the presence of implanted intra-cranial EEG electrodes, by presenting some histopathological and heat-shock immunopositive labeling observations in surgical tissue samples from patients who underwent the scanning procedure. METHODS: We performed histopathology and heat shock protein expression analyses on surgical tissue samples from nine patients who had been implanted with icEEG electrodes. Three patients underwent icEEG-fMRI and structural MRI (sMRI); three underwent sMRI only, all at similar time points after icEEG implantation; and three who did not undergo functional or sMRI with icEEG electrodes. RESULTS: The histopathological findings from the three patients who underwent icEEG-fMRI were similar to those who did not, in that they showed no evidence of additional damage in the vicinity of the electrodes, compared to cases who had no MRI with implanted icEEG electrodes. This finding was similar to our observations in patients who only underwent sMRI with implanted icEEG electrodes. CONCLUSION: This work provides unique evidence on the safety of functional MRI in the presence of implanted EEG electrodes. In the cases studied, icEEG-fMRI performed in accordance with our protocol based on low-SAR (≤0.1 W/kg) sequences at 1.5T using a head-transmit RF coil, did not result in measurable additional damage to the brain tissue in the vicinity of implanted electrodes. Furthermore, while one cannot generalize the results of this study beyond the specific electrode implantation and scanning conditions described herein, we submit that our approach is a useful framework for the post-hoc safety assessment of MR scanning with brain implants.
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Electrocorticografía , Electroencefalografía , Electrodos Implantados/efectos adversos , Electroencefalografía/métodos , Humanos , Inmunohistoquímica , Imagen por Resonancia Magnética/métodos , Ondas de RadioRESUMEN
BACKGROUND AND PURPOSE: This narrative review focuses on the role of mobile MRI and CT units in addressing the challenges of healthcare accessibility and patient wait times in Saudi Arabia. It underscores the growing demand for diagnostic imaging amid infrastructural and geographical barriers, emphasizing mobile units as innovative solutions for enhancing radiological services across diverse Saudi landscapes. The purpose of this study is to assess how these mobile technologies can mitigate service delays, improve patient outcomes, and support healthcare delivery in remote or underserved areas, reflecting on global trends towards more dynamic, patient-centered healthcare models. METHODS: This review utilizes an expanded database search and refined keywords to ensure comprehensive literature coverage. The study focused on peer-review articles and grey literatures that directly examined the impact of these mobile units on healthcare accessibility, wait times, and service delivery. A thematic analysis identified significant contributions to accessibility improvements, emergency responses, and rural healthcare, highlighting areas for further research and policy development. DISCUSSION: Mobile units have advanced technical specifications with high-field magnets and multi-slice CT scanners on par with fixed facilities. They prioritize patient comfort and safety with examination areas, control rooms, and waiting areas. Telemedicine capabilities allow real-time image transmission to specialists. Strategic deployment can address workforce shortages by distributing services equitably. Mobile units represent cost-effective solutions to expand healthcare access without fixed infrastructure. CONCLUSION: Integration of mobile MRI and CT units in Saudi Arabia can transform access to diagnostic imaging by decentralizing services and directly reaching patients, including rural areas. Evidence shows mobile units reduce diagnostic delays and optimize resource use. Despite challenges, strategic investments and collaborations can overcome obstacles to make radiological services more equitable, flexible and patient-focused in Saudi Arabia.
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The application of intracranial electroencephalography (icEEG) recording during functional magnetic resonance imaging (icEEG-fMRI) has allowed the study of the hemodynamic correlates of epileptic activity and of the neurophysiological basis of the blood oxygen level-dependent (BOLD) signal. However, the applicability of this technique is affected by data quality issues such as signal drop out in the vicinity of the implanted electrodes. In our center we have limited the technique to a quadrature head transmit and receive RF coil following the results of a safety evaluation. The purpose of this study is to gather further safety-related evidence for performing icEEG-fMRI using a body RF-transmit coil, to allow the greater flexibility afforded by the use of modern, high-density receive arrays, and therefore parallel imaging with benefits such as reduced signal drop-out and distortion artifact. Specifically, we performed a set of empirical temperature measurements on a 1.5T Siemens Avanto MRI scanner with the body RF-transmit coil in a range of electrode and connector cable configurations. The observed RF-induced heating during a high-SAR sequence was maximum in the immediate vicinity of a depth electrode located along the scanner's central axis (range: 0.2-2.4°C) and below 0.5°C at the other electrodes. Also for the high-SAR sequence, we observed excessive RF-related heating in connection cable configurations that deviate from our recommended setup. For the low-SAR sequence, the maximum observed temperature increase across all configurations was 0.3°C. This provides good evidence to allow simultaneous icEEG-fMRI to be performed utilizing the body transmit coil on the 1.5T Siemens Avanto MRI scanner at our center with acceptable additional risk by following a well-defined protocol.