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Dalhousie Radiology Research Office

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  • ItemOpen Access
    Coil migration through two flow-diverting stents
    (BMJ, 2024-01-18) Rogers, Patrick Scott; Volders, David; Pickett, Gwynedd; Vandorpe, Robert
    We report a case of a patient who initially presented with a subarachnoid haemorrhage secondary to a ruptured supraclinoid internal carotid artery (ICA) blister aneurysm. The patient was treated successfully with a flow diverter stent (FD) and coiling; however, a large aneurysm recurrence via a feeding posterior communicating artery (PCOM) was noted on the 1-year follow-up angiogram. During the retreatment, a second FD in the ICA resulted in insufficient aneurysm stasis. Therefore, the decision was made to coil sacrifice the PCOM via posterior circulation access. During the first coil deployment, the distal coil end migrated through the mesh of two overlapping FD into the middle cerebral artery. This complication was a previously unrecognised possibility given the composition of the FD. This case report aims to discuss this process as a potential complication during neurointerventional procedures using these devices.
  • ItemOpen Access
    Canadian Association of Radiologists Thoracic Imaging Referral Guideline
    (Sage Journals, 2023-12-15) Hamel, Candyce; Avard, Barb; Belanger, Catherine; Bourgouin, Patrick; Lam, Stephen; Manos, Daria; Michaud, Alan; Rowe, Brian H.; Sanders, Kevin; Bilawich, Ana-Maria
    The Canadian Association of Radiologists (CAR) Thoracic Expert Panel consists of radiologists, respirologists, emergency and family physicians, a patient advisor, and an epidemiologist/guideline methodologist. After developing a list of 24 clinical/diagnostic scenarios, a rapid scoping review was undertaken to identify systematically produced referral guidelines that provide recommendations for one or more of these clinical/diagnostic scenarios. Recommendations from 30 guidelines and contextualization criteria in the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) for guidelines framework were used to develop 48 recommendation statements across the 24 scenarios. This guideline presents the methods of development and the referral recommendations for screening/asymptomatic individuals, non-specific chest pain, hospital admission for non-thoracic conditions, long-term care admission, routine pre-operative imaging, post-interventional chest procedure, upper respiratory tract infection, acute exacerbation of asthma, acute exacerbation of chronic obstructive pulmonary disease, suspect pneumonia, pneumonia follow-up, immunosuppressed patient with respiratory symptoms/febrile neutropenia, chronic cough, suspected pneumothorax (non-traumatic), clinically suspected pleural effusion, hemoptysis, chronic dyspnea of non-cardiovascular origin, suspected interstitial lung disease, incidental lung nodule, suspected mediastinal lesion, suspected mediastinal lymphadenopathy, and elevated diaphragm on chest radiograph.
  • ItemOpen Access
    Is hepatocellular carcinoma viability important when using intraoperative blood salvage during liver transplantation?
    (Scopus, 2023-07-31) Nasser, Ahmed; Smith, Victoria; Campbell, Niamh; Rivers-Bowerman, Michael; Stueck, Ashley E.; Costa, Andreu; Arseneau, Riley; Westhaver, Lauren; Gala-Lopez, Boris
    Background: Intraoperative blood salvage and autotransfusion (IBS) is considered safe in liver transplantation for hepatocellular carcinoma (HCC). However, little is known about the potential impact of the viable tumor burden on recurrence and survival. This study investigated whether the presence of viable HCC during transplantation with IBS impacted HCC recurrence and patient survival. Methods: A retrospective study was conducted of liver transplants for patients with HCC in Atlantic Canada between 2005 and 2017. Information on locoregional treatment, IBS volume, and explant pathology was collected. Variables were analyzed to identify associations with HCC recurrence and patient survival via parametric and non-parametric tests. The Kaplan-Meier and log-rank tests were used to compare survival. Results: Sixty-eight subjects were included. IBS was used in 44.1% of the patients, with a median volume of 711 mL. Radiographic total tumor volume correlated well with the actual tumor viable volume (TVV) (Pearson’s r = 0.82, P < 0.01), but was overestimated by 50% when compared to the actual tumor burden on explant pathology. HCC recurrence was observed in 6 patients, and IBS was used in 5. Patients receiving IBS also had more viable tumors, but not a greater TVV. Overall patient survival did not exhibit significant differences according to the presence of viable tumors, vascular invasion, or satellitosis. Conclusion: IBS during liver transplantation was associated with significantly higher HCC recurrence in our limited series. However, the volume of viable HCC during the transplant procedure was not associated with any difference in tumor recurrence or patient survival. Keywords: Carcinoma, hepatocellular, Liver transplantation, Operative blood salvage, Recurrence, Survival
  • ItemOpen Access
    Plugging the Leak: Addressing the Mid-career Pipeline Challenge in Radiology
    (Sage Journals, 2023-08-07) Yong-Hing, Charlotte J.; Manos, Daria; Patlas, Michael N.; Spalluto, Lucy M.
    No abstract available
  • ItemOpen Access
    Can we rely on contrast-enhanced CT to identify pancreatic ductal adenocarcinoma? A population-based study in sensitivity and factors associated with false negatives
    (Springer, 2023-06-02) LeBlanc, Max; Kang, Jessie; Costa, Andreu F.
    Abstract Objectives: To determine the sensitivity of contrast-enhanced computed tomography (CECT) in detecting pancreatic ductal adenocarcinoma (PDAC) and identify factors associated with false negatives (FNs). Methods: Patients diagnosed with PDAC in 2014-2015 were retrospectively identified by a cancer registry. CECTs performed during the diagnostic interval were retrospectively classified as true positive (TP), indeterminate, or FN. Sensitivity TP/(TP+FN) was calculated for all CECTs and the following subgroups: protocol (uniphasic vs. biphasic); tumor size (≤ 2 cm vs. > 2 cm); and resectability (potentially resectable vs. unresectable). Multivariate logistic regression was performed to assess which of the following factors were associated with FN: clinical suspicion of PDAC; size >2 cm; presence of metastases; protocol; isoattenuating tumor; and potentially resectable disease on imaging. Results: In total, 176 CECTs (127 uniphasic; 49 biphasic) in 154 patients (90 men, mean age 72 ± 11 years) were included. Sensitivity was 125/149 (83.9%) overall and 87/106 (82.1%) and 38/43 (88.4%) for uniphasic and biphasic protocols, respectively. Sensitivity was decreased for tumors ≤ 2 cm (45.4% vs. 90.6%), no liver metastases (78.0% vs. 95.9%), and potentially resectable disease (65.3% vs. 93.0%). Factors significantly associated with FN were clinical suspicion (OR, 0.24, 95% CI: 0.07-0.75), size>2 cm (OR, 0.10, 95% CI: 0.02-0.44), absence of liver metastases (OR, 4.94, 95% CI: 1.29-22.99), and potentially resectable disease (OR, 4.13, 95% CI: 1.07-16.65). Conclusions: In our population, the overall sensitivity of CECT to detect PDAC is 83.9%; however, this is substantially lower in several scenarios, including patients with potentially resectable disease. This finding has important implications for patient outcomes and efforts to maximize CECT sensitivity should be sought. Clinical relevance statement: The sensitivity of CECT to detect PDAC is significantly decreased in the setting of sub-2 cm tumors and potentially resectable disease. A dedicated biphasic pancreatic CECT protocol has higher sensitivity and should be applied in patients with suspected pancreatic disease. Key points: • The sensitivities of contrast-enhanced CT for the detection of PDAC were 87/106 (82.1%) and 38/43 (88.4%) for uniphasic and biphasic protocols, respectively. • The sensitivity of contrast-enhanced CT was decreased for small tumors ≤ 2 cm (45.4% vs. 90.6%), if there were no liver metastases (78.0% vs. 95.9%), and with potentially resectable disease (65.3% vs. 93.0%). • Absence of liver metastases (OR, 4.94, 95% CI: 1.29-22.99) and potentially resectable disease (OR, 4.13, 95% CI: 1.07-16.65) were associated with a false--negative (FN) CT result; suspicion of malignancy on the imaging requisition (OR, 0.24, 95% CI: 0.07-0.75) and size > 2 cm (OR, 0.10, 95% CI: 0.02-0.44) were negatively associated with FN. Keywords: Computed tomography; Delayed diagnosis; Pancreatic ductal carcinoma; Sensitivity. © 2023. The Author(s), under exclusive licence to European Society of Radiology.
  • ItemOpen Access
    A Pragmatic Randomized Trial Comparing Surgical Clipping and Endovascular Treatment of Unruptured Intracranial Aneurysms
    (American Journal of Neuroradiology, 2023-06) Erdenebold, Undrakh-Erdene
    Abstract Background and purpose: Surgical clipping and endovascular treatment are commonly used in patients with unruptured intracranial aneurysms. We compared the safety and efficacy of the 2 treatments in a randomized trial. Materials and methods: Clipping or endovascular treatments were randomly allocated to patients with one or more 3- to 25-mm unruptured intracranial aneurysms judged treatable both ways by participating physicians. The study hypothesized that clipping would decrease the incidence of treatment failure from 13% to 4%, a composite primary outcome defined as failure of aneurysm occlusion, intracranial hemorrhage during follow-up, or residual aneurysms at 1 year, as adjudicated by a core lab. Safety outcomes included new neurologic deficits following treatment, hospitalization of >5 days, and overall morbidity and mortality (mRS > 2) at 1 year. There was no blinding. Results: Two hundred ninety-one patients were enrolled from 2010 to 2020 in 7 centers. The 1-year primary outcome, ascertainable in 290/291 (99%) patients, was reached in 13/142 (9%; 95% CI, 5%-15%) patients allocated to surgery and in 28/148 (19%; 95% CI, 13%-26%) patients allocated to endovascular treatments (relative risk: 2.07; 95% CI, 1.12-3.83; P = .021). Morbidity and mortality (mRS >2) at 1 year occurred in 3/143 and 3/148 (2%; 95% CI, 1%-6%) patients allocated to surgery and endovascular treatments, respectively. Neurologic deficits (32/143, 22%; 95% CI, 16%-30% versus 19/148, 12%; 95% CI, 8%-19%; relative risk: 1.74; 95% CI, 1.04-2.92; P = .04) and hospitalizations beyond 5 days (69/143, 48%; 95% CI, 40%-56% versus 12/148, 8%; 95% CI, 5%-14%; relative risk: 0.18; 95% CI, 0.11-0.31; P < .001) were more frequent after surgery. Conclusions: Surgical clipping is more effective than endovascular treatment of unruptured intracranial aneurysms in terms of the frequency of the primary outcome of treatment failure. Results were mainly driven by angiographic results at 1 year. © 2023 by American Journal of Neuroradiology.
  • ItemOpen Access
    Diagnostics and prospective outcome of a diffuse glioneuronal tumor with oligodendroglioma-like features and nuclear clusters after surgical resection (DGONC): a case report
    (Oxford University Press, 2022-10-25) Howie, Chelsea; Ahmad, Tahani; McFadden, Kathryn; Crooks, Bruce; McNeely, P Daniel; Walling, Simon; Rutledge, Robert; Sahm, Felix; Hinz, Felix; Jabado, Nada; Kieran, Mark; Erker, Craig
    Diffuse glioneuronal tumors with oligodendroglioma-like features and nuclear clusters (DGONC) are rare tumors of the central nervous system, having been added as a provi-sional diagnosis in the 2021 World Health Organization (WHO) Classification of Tumors of the central nervous system (CNS).1Retrospective studies report that these are most often mis-diagnosed and treated as high-grade tumors of the CNS.2,3However, this entity has demonstrated superior long-term survival in comparison. Given its novelty, there is currently no standard of care. We describe the diagnostic challenges, mo-lecular characteristics, prospective management, and outcome of a pediatric patient with a DGONC, with the aim to increase awareness of this entity and describe clinical behavior and di-agnostic uncertainties.
  • ItemOpen Access
    A survey of local diagnostic reference levels for the head, thorax, abdomen and pelvis computed tomography in Norway and Canada
    (Sage Journals, 2022-10-07) Tonkopi, Elena; Wikan, Eline Jahre; Hovland, Tor Olav; Høgset, Sivert; Kofod, Thomas Alexander; Sefenu, Selasi K; Hughes-Ryan, Emily; D'Entremont-O'Connell, Dakota; Gunn, Catherine; Holter, Tanja; Johansen, Safora
    Background Computed tomography (CT) contributes to 60% of the collective dose in medical imaging. Literature has demonstrated that patient dose varies across regions and countries. Establishing diagnostic reference levels (DRLs) contributes to the optimization of clinical practices and radiation protection. Purpose To survey the dose indices (CTDIvol and dose-length product) for frequently performed CT examinations from the chosen hospitals in Norway and Canada and to determine local DRLs (LDRLs) based on the collected data. Material and Methods The survey included eight scanners from two Norwegian hospitals and four scanners from four Canadian hospitals. Dosimetry data were collected for the following routine CT examinations: head, contrast-enhanced thorax, and abdomen and pelvis. Overall 480 adult average-sized patients from Norway and 360 from Canada were included in the survey. The LDRLs were determined as the 75th percentile of distributions of median values of dose indicators from different CT scanners. The differences in dose between scanners were determined using single-factor ANOVA. Results The LDRLs determined in Norway were higher overall than in Canada. The obtained values were compared to the national DRLs. The dose from several scanners in Norway exceeded national Norwegian DRLs, while Canadian LDRLs were below the Canadian reference levels. The differences between the means of the dose distributions from each scanner were statistically significant (p < 0.05) for all examinations with exception of identical scanners located in the same hospital and using the same protocols. Conclusion Observed dose variations even in the same hospital, or from the same scanner model confirmed the need for CT protocol optimization.
  • ItemOpen Access
    Canadian Association of Radiologists Prostate MRI White Paper
    (Sage Journals, 2022-11) Chang, Sylvia D.; Reinhold, Caroline; Kirkpatrick, Iain D. C.; Clarke, Sharon E.; Schieda, Nicola; Hurrell, Casey; Cool, Derek W.; Tunis, Adam S.; Alabousi, Abdullah; Diederichs, Brendan J.; Haider, Masoom A.
    Prostate cancer is the most common malignancy and the third most common cause of death in Canadian men. In light of evolving diagnostic pathways for prostate cancer and the increased use of MRI, which now includes its use in men prior to biopsy, the Canadian Association of Radiologists established a Prostate MRI Working Group to produce a white paper to provide recommendations on establishing and maintaining a Prostate MRI Programme in the context of the Canadian healthcare system. The recommendations, which are based on available scientific evidence and/or expert consensus, are intended to maintain quality in image acquisition, interpretation, reporting and targeted biopsy to ensure optimal patient care. The paper covers technique, reporting, quality assurance and targeted biopsy considerations and includes appendices detailing suggested reporting templates, quality assessment tools and sample image acquisition protocols relevant to the Canadian healthcare context.
  • ItemOpen Access
    Endometrial osseous metaplasia with secondary infertility
    (CMAJ Group, 2022-06) White, Justin; Hickey, Joanne; Gilmour, Donna; Ansari, Afshin
    A 32-year-old woman with a history of an early pregnancy loss followed by a term birth presented to her gynecologist with difficulty conceiving and amenorrhea. Her second pregnancy, the live birth, had resulted in a vaginal delivery followed by manual removal of an adherent posterior placenta. Twenty months postpartum, she had ongoing amenorrhea, despite not breastfeeding. Endocrine investigations for follicle-stimulating hormone, luteinizing hormone, thyroid-stimulating hormone and prolactin were normal.
  • ItemOpen Access
    Resting state functional connectivity in SLE patients and association with cognitive impairment and blood–brain barrier permeability (Postprint)
    (Oxford Acadmic, 2022-06-14) Hanly, John G.; Robertson, Jason W.; Legge, Alexandra; Kamintsky, Lyna; Aristi, Guillermo; Friedman, Alon; Beyea, Steven D.; Frisk, John D.; Omisade, Antonina; Calkin, Cynthia; Bardouille, Tim; Bowen, Chris; Matheson, Kara; Hashmi, Javeria
    Objective Extensive blood–brain barrier (BBB) leakage has been linked to cognitive impairment in SLE. This study aimed to examine the associations of brain functional connectivity (FC) with cognitive impairment and BBB dysfunction among patients with SLE. Methods Cognitive function was assessed by neuropsychological testing (n = 77). Resting-state FC (rsFC) between brain regions, measured by functional MRI (n = 78), assessed coordinated neural activation in 131 regions across five canonical brain networks. BBB permeability was measured by dynamic contrast-enhanced MRI (n = 61). Differences in rsFC were compared between SLE patients with cognitive impairment (SLE-CI) and those with normal cognition (SLE-NC), between SLE patients with and without extensive BBB leakage, and with healthy controls. Results A whole-brain rsFC comparison found significant differences in intra-network and inter-network FC in SLE-CI vs SLE-NC patients. The affected connections showed a reduced negative rsFC in SLE-CI compared with SLE-NC and healthy controls. Similarly, a reduced number of brain-wide connections was found in SLE-CI patients compared with SLE-NC (P = 0.030) and healthy controls (P = 0.006). Specific brain regions had a lower total number of brain-wide connections in association with extensive BBB leakage (P = 0.011). Causal mediation analysis revealed that 64% of the association between BBB leakage and cognitive impairment in SLE patients was mediated by alterations in FC. Conclusion SLE patients with cognitive impairment had abnormalities in brain rsFC which accounted for most of the association between extensive BBB leakage and cognitive impairment.
  • ItemOpen Access
    Comparison of Bolus Versus Dual-Syringe Administration Systems on Glass Yttrium-90 Microsphere Deposition in an In Vitro Microvascular Hepatic Tumor Model
    (Elsevier, 2023-01) Miller, Samuel R.; Jernigan, Shaphan R.; Abraham, Robert J.; Buckner, Gregory D.
    Purpose To utilize an in vitro microvascular hepatic tumor model to compare the deposition characteristics of glass yttrium-90 microspheres using the dual-syringe (DS) and traditional bolus administration methods. Materials and Methods The microvascular tumor model represented a 3.5-cm tumor in a 1,400-cm3 liver with a total hepatic flow of 160 mL/min and was dynamically perfused. A microcatheter was placed in a 2-mm artery feeding the tumor model and 2 additional nontarget arteries. Glass microspheres with a diameter of 20–30 μm were administered using 2 methods: (a) DS delivery at a concentration of 50 mg/mL in either a single, continuous 2-mL infusion or two 1-mL infusions and (b) bolus delivery (BD) of 100 mg of microspheres in a single 3-mL infusion. Results Overall, the degree of on-target deposition of the microspheres was 85% ± 11%, with no significant differences between the administration methods. Although the distal penetration into the tumor arterioles was approximately 15 mm (from the second microvascular bifurcation of the tumor model) for all the cases, the distal peak particle counts were significantly higher for the DS delivery case (approximately 5 × 105 microspheres achieving distal deposition vs 2 × 105 for the BD case). This resulted in significantly higher deposition uniformity within the tumor model (90% for the DS delivery case vs 80% for the BD case, α = 0.05). Conclusions The use of this new in vitro microvascular hepatic tumor model demonstrated that the administration method can affect the deposition of yttrium-90 microspheres within a tumor, with greater distal deposition and more uniform tumor coverage when the microspheres are delivered at consistent concentrations using a DS delivery device. The BD administration method was associated with less favorable deposition characteristics of the microspheres.
  • ItemOpen Access
    Systematic review of diffuse hemispheric glioma, H3 G34-mutant: Outcomes and associated clinical factors
    (Oxford Academic, 2022-08-19) Crowell, Cameron; Mata-Mbemba, Daddy; Bennett, Julie; Matheson, Kara; Mackley, Michael; Perreault, Sébastien; Erker, Craig
    Background: A comprehensive review and description of the clinical features that impact prognosis for patients with diffuse hemispheric glioma, H3 G34-mutant (G34-DHG) is needed. Understanding survival and prognostic features is paramount for clinical advancements and patient care. Methods: PubMed, Embase, and Google Scholar were searched for English articles published between January 1, 2012 and June 30, 2021. Eligible studies included patient(s) of any age diagnosed with an H3 G34-mutant brain tumor with at least one measure of survival or progression. Patient-level data were pooled for analyses. This study was prospectively registered in PROSPERO (CRD42021267764) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. Results: Twenty-seven studies met the criteria with a total of 135 patients included. Median age at diagnosis was 15.8 years (interquartile range [IQR]: 13.3–22.0) with 90% having localized disease. Co-occurring alterations included ATRX mutation in 93%, TP53 mutation in 88%, and MGMT promoter methylation in 70%. Median time-to-progression was 10.0 months (IQR: 6.0–18.0) and median overall survival was 17.3 months (95% CI: 15.0 to 22.9). The median time from progression to death was 5.0 months (IQR: 3.0–11.7). Factors associated with survival duration were age, as patients ≥18 y/o demonstrated longer survival (hazard ratio [HR] =2.05, 95% CI: 1.16 to 3.62), and degree of upfront resection, as near or gross-total resection demonstrated longer survival compared to those with less than near-total resection (HR = 3.75, 95% CI: 2.11 to 6.62). Conclusion: This systematic review highlights available clinical data for G34-DHG demonstrating poor outcomes and important prognostic features, while serving as a baseline for future research and clinical trials.
  • ItemOpen Access
    Transabdominal ultrasound of pancreatic ductal adenocarcinoma: A multi-centered population-based study in sensitivity, associated diagnostic intervals, and survival (preprint)
    (Elsevier, 2022-11) Kang, Jessie; Abdolell, Mohamed; Costa, Andreu F.
    Abstract Objectives To determine the sensitivity of ultrasound (US) in detecting pancreatic ductal adenocarcinoma in our region, to identify factors associated with US test result, and assess the impact on the diagnostic interval and survival. Methods Patients diagnosed between January 1, 2014 and December 31, 2015 in Nova Scotia, Canada were identified by a cancer registry. US performed prior to diagnosis were retrospectively graded as true positive (TP), indeterminate or false negative (FN). Amongst US results, differences in age, weight and tumor size were assessed [one-way analysis of variance (ANOVA)]. Associations between result and sex, tumor location (proximal/distal), clinical suspicion of malignancy, and visualization of the pancreas, tumor, secondary signs and liver metastases were assessed (Chi-square). Mean follow-up imaging, diagnostic, and survival intervals were assessed (one-way ANOVA). Results One hundred thirteen US of 107 patients (54 women; mean 70 ± 13 years) were graded as follows: 48/113 (42.5%) TPs; 42/113 (37.2%) indeterminates; and 23/113 (20.4%) FNs. Sensitivity was 48/71(67.6%). There was no difference in age, weight or tumor size amongst US result (P > 0.5). FNs had proportionally more men (P = 0.011) and lacked clinical suspicion of malignancy (P = 0.0006); TPs had proportionally more proximal tumors (P = 0.017). US result was associated with visualization of the pancreas, tumor, secondary signs and liver metastases (P < 0.005). FNs had longer mean follow-up imaging (P < 0.0001) and diagnostic (P = 0.0007) intervals, and worse mean survival (P = 0.034). Conclusions In our region, the sensitivity of US in detecting pancreatic ductal adenocarcinoma is 67.6%. A false negative US is associated with delayed diagnostic work-up and worse mean survival.
  • ItemOpen Access
    No difference in cerebral perfusion between the wild-type and the 5XFAD mouse model of Alzheimer’s disease
    (Nature Research, 2022-12) DeBay, Drew R.; Phi, Tân-Trào; Bowen, Chris V.; Burrell, Steven C.; Darvesh, Sultan
    Abstract Neuroimaging with [2,2-dimethyl-3-[(2R,3E)-3-oxidoiminobutan-2-yl]azanidylpropyl]-[(2R,3E)-3-hydroxyiminobutan-2-yl]azanide;oxo(99Tc)technetium-99(3+) ([99mTc]HMPAO) single photon emission computed tomography (SPECT) is used in Alzheimer’s disease (AD) to evaluate regional cerebral blood flow (rCBF). Hypoperfusion in select temporoparietal regions has been observed in human AD. However, it is unknown whether AD hypoperfusion signatures are also present in the 5XFAD mouse model. The current study was undertaken to compare baseline brain perfusion between 5XFAD and wild-type (WT) mice using [99mTc]HMPAO SPECT and determine whether hypoperfusion is recapitulated in 5XFAD mice. 5XFAD and WT mice underwent a 45 min SPECT scan, 20 min after [99mTc]HMPAO administration. Whole brain and regional standardized uptake values (SUV) and regional relative standardized uptake values (SUVR) with whole brain reference were compared between groups. Brain perfusion was similar between WT and 5XFAD brains. Whole brain [99mTc]HMPAO retention revealed no significant difference in SUV (5XFAD, 0.372 ± 0.762; WT, 0.640 ± 0.955; p = 0.536). Similarly, regional analysis revealed no significant differences in [99mTc]HMPAO metrics between groups (SUV: 0.357 ≤ p ≤ 0.640; SUVR: 0.595 ≤ p ≤ 0.936). These results suggest apparent discrepancies in rCBF between human AD and the 5XFAD model. Establishing baseline perfusion patterns in 5XFAD mice is essential to inform pre-clinical diagnostic and therapeutic drug discovery programs.