Imaging Biological Pathways in Abdominal Aortic Aneurysms Using Positron Emission Tomography.

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Prospect of positron emission tomography for abdominal aortic aneurysm risk stratification.

Abdominal aortic aneurysm (AAA) disease is characterized by an asymptomatic, permanent, focal dilatation of the abdominal aorta progressing towards rupture, which confers significant mortality. Patient management and surgical decisions rely on aortic diameter measurements via abdominal ultrasound surveillance. However, AAA rupture can occur at small diameters or may never occur at large diameters, implying that anatomical size is not necessarily a sufficient indicator. Molecular imaging may help identify high-risk patients through AAA evaluation independent of aneurysm size, and there is the question of the potential role of positron emission tomography (PET) and emerging role of novel radiotracers for AAA. Therefore, this review summarizes PET studies conducted in the last 10 years and discusses the usefulness of PET radiotracers for AAA risk stratification. The most frequently reported radiotracer was [18F]fluorodeoxyglucose, indicating inflammatory activity and reflecting the biomechanical properties of AAA. Emerging radiotracers include [18F]-labeled sodium fluoride, a calcification marker, [64Cu]DOTA-ECL1i, an indicator of chemokine receptor type 2 expression, and [18F]fluorothymidine, a marker of cell proliferation. For novel radiotracers, preliminary trials in patients are warranted before their widespread clinical implementation. AAA rupture risk is challenging to evaluate; therefore, clinicians may benefit from PET-based risk assessment to guide patient management and surgical decisions.

Cell proliferation detected using [18F]FLT PET/CT as an early marker of abdominal aortic aneurysm.

BACKGROUND: Abdominal aortic aneurysm (AAA) is a focal aortic dilatation progressing towards rupture. Non-invasive AAA-associated cell proliferation biomarkers are not yet established. We investigated the feasibility of the cell proliferation radiotracer, fluorine-18-fluorothymidine ([18F]FLT) with positron emission tomography/computed tomography (PET/CT) in a progressive pre-clinical AAA model (angiotensin II, AngII infusion). METHODS AND RESULTS: Fourteen-week-old apolipoprotein E-knockout (ApoE-/-) mice received saline or AngII via osmotic mini-pumps for 14 (n = 7 and 5, respectively) or 28 (n = 3 and 4, respectively) days and underwent 90-minute dynamic [18F]FLT PET/CT. Organs were harvested from independent cohorts for gamma counting, ultrasound scanning, and western blotting. [18F]FLT uptake was significantly greater in 14- (n = 5) and 28-day (n = 3) AAA than in saline control aortae (n = 5) (P < 0.001), which reduced between days 14 and 28. Whole-organ gamma counting confirmed greater [18F]FLT uptake in 14-day AAA (n = 9) compared to saline-infused aortae (n = 4) (P < 0.05), correlating positively with aortic volume (r = 0.71, P < 0.01). Fourteen-day AAA tissue showed increased expression of thymidine kinase-1, equilibrative nucleoside transporter (ENT)-1, ENT-2, concentrative nucleoside transporter (CNT)-1, and CNT-3 than 28-day AAA and saline control tissues (n = 3 each) (all P < 0.001). CONCLUSIONS: [18F]FLT uptake is increased during the active growth phase of the AAA model compared to saline control mice and late-stage AAA.

A Physiotherapeutic Approach to a Rare Case of Windswept Deformity in a Male Adolescent.

Primary hyperparathyroidism (PHPT) can lead to a rare condition in children and adolescents known as windswept deformity. This deformity involves one knee exhibiting an abnormal outward angulation (valgus deformity), while the other knee shows an abnormal inward angulation (varus deformity). This asymmetrical syndrome, resembling the effect of strong winds, gives the impression that the knees are being swept in opposite directions. Various factors, such as structural bone or joint defects, accidents, or underlying disorders, can contribute to the development of windswept deformity. PHPT, a common endocrine condition characterized by elevated levels of parathyroid hormone and blood calcium, is unusual in the pediatric and adolescent populations. It can result in complications like osteoporosis and bone abnormalities, with genu valgus (outward knee angulation) being an exceptionally rare symptom. This case discusses a 19-year-old male who underwent corrective surgery for genu valgus and presented with windswept deformity due to teenage hyperparathyroidism. The case study outlines the physiotherapeutic rehabilitation strategy, emphasizing treatments such as cryotherapy, patellar mobilization, and gait training. Tailored physical therapy rehabilitation plays a crucial role in the postoperative care of patients undergoing corrective osteotomies. The results indicated a significant improvement in muscle strength, an expansion of the range of motion (ROM), and a noticeable enhancement in the individual's functional autonomy following adherence to the postoperative physiotherapy (PT) plan.

Positive Outcomes of Physiotherapy Intervention in a Wedge Compression Fracture of the L1 Vertebra: A Case Report.

The thoracolumbar spine is prone to vertebral compression fractures (VCFs). An injury mechanism known as flexion compression is responsible for thoracolumbar spine compression fractures. Usually, this mechanism affects the longitudinal ligament at the front and the front part of the vertebral body as the first components. Pain is the first and foremost symptom; here we present a case report of a 34-year-old male, who came to the hospital with complaints of back pain, and difficulty in breathing followed by a road traffic accident (RTA). MRI and X-ray investigations were done. The patient was diagnosed with a fracture of the anterolateral aspect of the right fourth and fifth ribs and posterolateral aspect of the sixth rib, acute anterior wedge compression fracture of the L1 vertebra, and bilateral minimal pneumothorax and haemothorax. The patient was managed surgically with post-decompression and spinal fusion at the D12-L2 level. The outcomes used were the Oswestry Low-Back Disability Questionnaire, the numerical pain rating scale, and Manual Muscle Testing (MMT). This case report specifies the physiotherapeutic rehabilitation protocol, mainly focusing on techniques like breathing exercises, and upper limb and lower limb strengthening along with trunk and pelvic floor muscles strengthening.

[18F]Fluorothymidine Uptake in the Porcine Pancreatic Elastase-Induced Model of Abdominal Aortic Aneurysm.

The porcine pancreatic elastase (PPE) model is a common preclinical model of abdominal aortic aneurysms (AAA). Some notable characteristics of this model include the low aortic rupture rate, non-progressive disease course, and infra-renal AAA formation. Enhanced [18F]fluorothymidine ([18F]FLT) uptake on positron emission tomography/computed tomography (PET/CT) has previously been reported in the angiotensin II-induced murine model of AAA. Here, we report our preliminary findings of investigating [18F]FLT uptake in the PPE murine model of AAA. [18F]FLT uptake was found to be substantially increased in the abdominal areas recovering from the surgery, whilst it was not found to be significantly increased within the PPE-induced AAA, as confirmed using in vivo PET/CT and ex vivo whole-organ gamma counting (PPE, n = 7; controls, n = 3). This finding suggests that the [18F]FLT may not be an appropriate radiotracer for this specific AAA model, and further studies with larger sample sizes are warranted to elucidate the pathobiology contributing to the reduced uptake of [18F]FLT in this model.

Preclinical Imaging Biomarkers for Postischaemic Neurovascular Remodelling.

In the pursuit of understanding the pathological alterations that underlie ischaemic injuries, such as vascular remodelling and reorganisation, there is a need for recognising the capabilities and limitations of in vivo imaging techniques. Thus, this review presents contemporary published research of imaging modalities that have been implemented to study postischaemic neurovascular changes in small animals. A comparison of the technical aspects of the various imaging tools is included to set the framework for identifying the most appropriate methods to observe postischaemic neurovascular remodelling. A systematic search of the PubMed® and Elsevier's Scopus databases identified studies that were conducted between 2008 and 2018 to explore postischaemic neurovascular remodelling in small animal models. Thirty-five relevant in vivo imaging studies are included, of which most made use of magnetic resonance imaging or positron emission tomography, whilst various optical modalities were also utilised. Notably, there is an increasing trend of using multimodal imaging to exploit the most beneficial properties of each imaging technique to elucidate different aspects of neurovascular remodelling. Nevertheless, there is still scope for further utilising noninvasive imaging tools such as contrast agents or radiotracers, which will have the ability to monitor neurovascular changes particularly during restorative therapy. This will facilitate more successful utility of the clinical imaging techniques in the interpretation of neurovascular reorganisation over time.