Benefits of home-based foot neuromuscular electrical stimulation on self-reported function, leg pain and other leg symptoms among community-dwelling older adults: a sham-controlled randomised clinical trial.

INTRODUCTION: Lower leg pain and symptoms, and poor leg circulation are common in older adults. These can significantly affect their function and quality of life. Neuromuscular electrical stimulation (NMES) applied via the feet as 'foot NMES' activates the leg musculovenous pump. This study investigated the effects of foot NMES administered at home using Revitive® among community-dwelling older adults with lower leg pain and/or other lower leg symptoms such as cramps, or sensations of tired, aching, and heavy feeling legs. METHODS: A randomised placebo-controlled study with three groups (2 NMES, 1 Sham) and three assessments (baseline, week 8, week 12 follow-up) was carried out. Self-reported function using Canadian occupational performance measure (COPM), leg pain, overall leg symptoms score (heaviness, tiredness, aching, or cramps), and ankle blood flow were assessed. Analysis of covariance (ANCOVA) and logistic regression were used to compare the groups. Statistical significance was set at p < 0.05 (two-sided 5%). RESULTS: Out of 129 participants enrolled, 114 completed the study. The improvement in all outcomes were statistically significant for the NMES interventions compared to Sham at both week 8 (p < 0.01) and week 12 (p < 0.05). The improvement in COPM met the minimal clinically important difference (MCID) for the NMES interventions compared to Sham at both week 8 (p < 0.005) and week 12 (p < 0.05). Improvement in leg pain met MCID at week 8 compared to Sham (p < 0.05). Ankle blood flow increased approximately 3-fold during treatment compared to Sham. Compliance with the interventions was high and no device-related adverse events were reported. CONCLUSIONS: The home-based foot NMES is safe, and significantly improved self-reported function, leg pain and overall leg symptoms, and increased ankle blood flow compared to a Sham among older adults. TRIAL REGISTRATION: The trial was prospectively registered in ISRCTN on 17/06/2019 with registration number ISRCTN10576209. It can be accessed at https://www.isrctn.com/ISRCTN10576209 .

In vitro and in vivo optimized reconstruction for low-keV virtual monoenergetic photon-counting detector CT angiography of lower legs.

BACKGROUND: Lower extremity peripheral artery disease frequently presents with calcifications which reduces the accuracy of computed tomography (CT) angiography, especially below-the-knee. Photon-counting detector (PCD)-CT offers improved spatial resolution and less calcium blooming. We aimed to identify the optimal reconstruction parameters for PCD-CT angiography of the lower legs. METHODS: Tubes with different diameters (1-5 mm) were filled with different iodine concentrations and scanned in a water container. Images were reconstructed with 0.4 mm isotropic resolution using a quantitative kernel at all available sharpness levels (Qr36 to Qr76) and using different levels of quantum iterative reconstruction (QIR-2-4). Noise and image sharpness were determined for all reconstructions. Additionally, CT angiograms of 20 patients, reconstructed with a medium (Qr44), sharp (Qr60), and ultrasharp (Qr72) kernel at QIR-2-4, were evaluated by three readers assessing noise, delineation of plaques and vessel walls, and overall quality. RESULTS: In the phantom study, increased kernel sharpness led to higher image noise (e.g., 16, 38, 77 HU for Qr44, Qr60, Qr72, and QIR-3). Image sharpness increased with increasing kernel sharpness, reaching a plateau at the medium-high level 60. Higher QIR levels decreased image noise (e.g., 51, 38, 25 HU at QIR-2-4 and Qr60) without reducing vessel sharpness. The qualitative in vivo results confirmed these findings: the sharp kernel (Qr60) with the highest QIR yielded the best overall quality. CONCLUSION: The combination of a sharpness level optimized reconstruction kernel (Qr60) and the highest QIR level yield the best image quality for PCD-CT angiography of the lower legs when reconstructed at 0.4-mm resolution. RELEVANCE STATEMENT: Using high-resolution PCD-CT angiography with optimized reconstruction parameters might improve diagnostic accuracy and confidence in peripheral artery disease of the lower legs. KEY POINTS: Effective exploitation of the potential of PCD-CT angiography requires optimized reconstruction parameters. Too soft or too sharp reconstruction kernels reduce image quality. The highest level of quantum iterative reconstruction provides the best image quality.

Aetiologies of Leg Pain among Patients Presenting to a Vascular Surgery Clinic.

OBJECTIVE: To determine the frequency and pattern of different aetiologies of leg pain among patients visiting vascular surgery clinics. STUDY DESIGN: Cross-sectional study. Place and Duration of the Study: Vascular Surgery Clinics of the Aga Khan University Hospital, Karachi, Pakistan, between February 2021 and June 2023. METHODOLOGY: This study examined patients presenting with leg pain for the first time at vascular surgery clinics. The socio-demographic and clinical data including the clinical symptoms, physical examination findings, and management of leg pain were noted using a specially designed proforma. RESULTS: In a total of 142 patients (200 limbs), 82 (57.7%) were females and 60 (42.3%) were males, with a mean age of 46.8 ± 15.1 years. The patients' mean body mass index (BMI) was 30.2 ± 7.9 kg/m2. Ninety-one (64.1%) patients had a predominantly standing job compared to 51 (35.9%) patients who had a predominantly sitting job. The most common aetiology of leg pain was chronic venous insufficiency (CVI), diagnosed in 107 (53.5%) patients, followed by neurogenic pain [41 (20.5%)], musculoskeletal pain including knee osteoarthritis [30 (15.0%)], and arterial insufficiency [22 (11.0%)].  Conclusion: CVI followed by neuropathic pain was the leading cause of leg pain in vascular surgery clinics at a tertiary care hospital. KEY WORDS: Chronic venous insufficiency, Arterial insufficiency, Vascular surgery, Leg pain, Musculoskeletal pain, Neuralgia.

Endurance Training Improves Leg Proton Release and Decreases Potassium Release During High-Intensity Exercise in Normoxia and Hypobaric Hypoxia.

AIM: To assess the impact of endurance training on skeletal muscle release of H+ and K+. METHODS: Nine participants performed one-legged knee extension endurance training at moderate and high intensities (70%-85% of Wpeak), three to four sessions·week-1 for 6 weeks. Post-training, the trained and untrained (control) leg performed two-legged knee extension at low, moderate, and high intensities (40%, 62%, and 83% of Wpeak) in normoxia and hypoxia (~4000 m). The legs were exercised simultaneously to ensure identical arterial inflow concentrations of ions and metabolites, and identical power output was controlled by visual feedback. Leg blood flow was measured (ultrasound Doppler), and acid-base variables, lactate- and K+ concentrations were assessed in arterial and femoral venous blood to study K+ and H+ release. Ion transporter abundances were assessed in muscle biopsies. RESULTS: Lactate-dependent H+ release was similar in hypoxia to normoxia (p = 0.168) and was lower in the trained than the control leg at low-moderate intensities (p = 0.060-0.006) but similar during high-intensity exercise. Lactate-independent and total H+ releases were higher in hypoxia (p < 0.05) and increased more with power output in the trained leg (leg-by-power output interactions: p = 0.02). K+ release was similar at low intensity but lower in the trained leg during high-intensity exercise in normoxia (p = 0.024) and hypoxia (p = 0.007). The trained leg had higher abundances of Na+/H+ exchanger 1 (p = 0.047) and Na+/K+ pump subunit α (p = 0.036). CONCLUSION: Moderate- to high-intensity endurance training increases lactate-independent H+ release and reduces K+ release during high-intensity exercise, coinciding with increased Na+/H+ exchanger 1 and Na+/K+ pump subunit α muscle abundances.

Isolated Calf Muscle Venous Thrombosis: A Review of Anticoagulation Strategies.

Deep vein thrombosis (DVT) of the lower extremities is divided into 2 categories according to the extent of thrombosis involvement. Thrombosis involving the popliteal vein, femoral vein, and iliac vein is classified as proximal DVT, while thrombosis involving the anterior tibial vein, posterior tibial vein, peroneal vein, and calf muscles vein is regarded as distal DVT. There are updated guidelines for the anticoagulant treatment for proximal DVT, but the best anticoagulant treatment for distal DVT is still controversial, especially for isolated calf muscular vein thrombosis (CMVT). The risk of isolated CMVT extending to the proximal deep veins and developing into pulmonary embolism is lower than with distal DVT. Some scholars believe that isolated CMVT has the risk of evolving into proximal deep vein thrombosis and pulmonary embolism, and active early anticoagulation therapy can reduce the risk and benefit patients. In addition, based on the characteristics of CMVT and the bleeding risk of anticoagulation therapy, some studies have recommended use of non-anticoagulation methods such as compression therapy. There is still a lack of multicenter, big-data, randomized, controlled trials on the benefits or risks of anticoagulation therapy. Among scholars who support anticoagulation therapy, there is still a lack of consensus on the optimal duration. This article reviews the current evidence on anticoagulant therapy for patients with isolated CMVT and how long the anticoagulation course should be if anticoagulation is required. Our research will provide a theoretical basis for subsequent research. More prospective studies with larger sample sizes are needed to provide more clinical evidence.

Assessing Leg Blood Flow and Cardiac Output During Running Using Thermodilution.

Cardiac output (Q̇C) and leg blood flow (Q̇LEG) can be measured simultaneously with high accuracy using transpulmonary and femoral vein thermodilution with a single-bolus injection. The invasive measure has offered important insight into leg hemodynamics and blood flow distribution during exercise. Despite being the natural modality of exercise in humans, there has been no direct measure of Q̇LEG while running in humans. We sought to determine the feasibility of the thermodilution technique for measuring Q̇LEG and conductance during high-intensity running, in an exploratory case study. A trained runner (30 years male) completed two maximal incremental tests on a cycle ergometer and motorized treadmill. Q̇LEG and Q̇C were determined using the single-bolus thermodilution technique. Arterial and venous blood were sampled throughout exercise, with continuous monitoring of metabolism, intra-arterial and venous pressure, and temperature. The participant reached a greater peak oxygen uptake (V̇O2peak) during running relative to cycling (74 vs. 68 mL/kg/min) with comparable Q̇LEG (19.0 vs. 19.5 L/min) and Q̇C (27.4 vs. 26.2 L/min). Leg vascular conductance was greater during high-intensity running relative to cycling (82 vs. 70 mL/min/mmHg @ ~80% V̇O2peak). The "beat phenomenon" was apparent in femoral flow while running, producing large gradients in conductance (62-90 mL/min/mmHg @ 70% V̇O2peak). In summary, we present the first direct measure of Q̇LEG and conductance in a running human. Our findings corroborate several assumptions about Q̇LEG during running compared with cycling. Importantly, we demonstrate that using thermodilution in running exercise can be completed effectively and safely.

[Lower extremity arterial disease (LEAD)]. / Periphere arterielle Verschlusskrankheit (pAVK).

Peripheral arterial occlusive disease (PAOD) is a frequent manifestation of atherosclerosis with a high risk of cardiovascular events (myocardial infarction, stroke, amputation, cardiovascular death). A distinction is made between the stable form of intermittent claudication and chronic limb-threatening ischemia (CLTI, pain at rest, wounds). The most frequent risk factors are diabetes mellitus and smoking. As the disease is often asymptomatic early diagnostic necessary. Measurement of the ankle-brachial index (ABI) is suitable for screening. Consistent treatment of cardiovascular risk factors and antithrombotic medication are important. At the stage of intermittent claudication, exercise training should be performed. In CLTI early endovascular or surgical revascularization must be performed to avoid amputation of the extremity.

α-Adrenergic regulation of skeletal muscle blood flow during exercise in patients with heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction (HFpEF) has been characterized by lower blood flow to exercising limbs and lower peak oxygen utilization ( V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ ), possibly associated with disease-related changes in sympathetic (α-adrenergic) signaling. Thus, in seven patients with HFpEF (70 ± 6 years, 3 female/4 male) and seven controls (CON) (66 ± 3 years, 3 female/4 male), we examined changes (%Δ) in leg blood flow (LBF, Doppler ultrasound) and leg V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ to intra-arterial infusion of phentolamine (PHEN, α-adrenergic antagonist) or phenylephrine (PE, α1-adrenergic agonist) at rest and during single-leg knee-extension exercise (0, 5 and 10 W). At rest, the PHEN-induced increase in LBF was not different between groups, but PE-induced reductions in LBF were lower in HFpEF (-16% ± 4% vs. -26% ± 5%, HFpEF vs. CON; P < 0.05). During exercise, the PHEN-induced increase in LBF was greater in HFpEF at 10 W (16% ± 8% vs. 8% ± 5%; P < 0.05). PHEN increased leg V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ in HFpEF (10% ± 3%, 11% ± 6%, 15% ± 7% at 0, 5 and 10 W; P < 0.05) but not in controls (-1% ± 9%, -4% ± 2%, -1% ± 5%; P = 0.24). The 'magnitude of sympatholysis' (PE-induced %Δ LBF at rest - PE-induced %Δ LBF during exercise) was lower in patients with HFpEF (-6% ± 4%, -6% ± 6%, -7% ± 5% vs. -13% ± 6%, -17% ± 5%, -20% ± 5% at 0, 5 and 10 W; P < 0.05) and was positively related to LBF, leg oxygen delivery, leg V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ , and the PHEN-induced increase in LBF (P < 0.05). Together, these data indicate that excessive α-adrenergic vasoconstriction restrains blood flow and limits V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ of the exercising leg in patients with HFpEF, and is related to impaired functional sympatholysis in this patient group. KEY POINTS: Sympathetic (α-adrenergic)-mediated vasoconstriction is exaggerated during exercise in patients with heart failure with preserved ejection fraction (HFpEF), which may contribute to limitations of blood flow, oxygen delivery and oxygen utilization in the exercising muscle. The ability to adequately attenuate α1-adrenergic vasoconstriction (i.e. functional sympatholysis) within the vasculature of the exercising muscle is impaired in patients with HFpEF. These observations extend our current understanding of HFpEF pathophysiology by implicating excessive α-adrenergic restraint and impaired functional sympatholysis as important contributors to disease-related impairments in exercising muscle blood flow and oxygen utilization in these patients.

Haemodynamic effect of a leg compression bandage on the distal posterior tibial artery using 4D flow magnetic resonance imaging: A quantitative study.

The uncertainty concerning the physiological effects of compression bandaging on the peripheral blood flow is a challenge for healthcare professionals. The main objective was to determine the haemodynamic impact on the distal posterior tibial artery after the application of a high-compression leg multicomponent bandaging system using 4D flow magnetic resonance imaging. Leg dominance disparities of the posterior tibial artery before and after the application of the compressive bandage were also analysed. Twenty-eight healthy female volunteers were recruited (mean: 25.71, standard deviation: 4.74 years old) through a non-probability convenience sampling. The 4D flow magnetic resonance imaging of the distal tibial posterior artery was performed in all participants, first under standard resting conditions and after the application of a compression bandage in the leg. When the strong compressive bandage was applied, the area of the assessed artery decreased by 14.2%, whilst the average speed increased by 19.6% and the flow rate increased by 184.8%. There were differences between the haemodynamic parameters of both legs according to dominance, being statistically significantly lower in the dominant leg. The application of strong compressive bandaging significantly increases the arterial flow and mean velocity in the distal segment of the posterior tibial artery, in healthy volunteers by 4D flow magnetic resonance imaging. In this study, leg dominance influenced some of the haemodynamic parameters. According to the results, leg compression bandages cannot be contraindicated in vascular ulcers with arterial compromise.

Calf deep veins are safe and feasible accesses for the endovascular treatment of acute lower extremity deep vein thrombosis.

This study was designed to assess the optimal access route for the endovascular treatment of acute lower extremity deep vein thrombosis. This was a retrospective analysis of patients with acute lower extremity deep venous thrombosis who underwent endovascular treatment from February 2009 to December 2020. Patients underwent non-direct calf deep vein puncture (NDCDVP) from February 2009 to December 2011 and direct calf deep vein puncture (DCDVP) from January 2012 to December 2020. Catheter directed thrombolysis (CDT) was used to treat all patients in the NDCDVP group, whereas patients in the DCDVP group were treated with CDT or the AngioJet rhyolitic thrombectomy system. In patients exhibiting iliac vein compression syndrome, the iliac vein was dilated and implanted with a stent. Technical success rates and perioperative complication rates were compared between these two treatment groups. The NDCDVP group included 83 patients (40 males, 43 females) with a mean age of 55 ± 16 years, while the DCDVP group included 487 patients (231 males. 256 females) with a mean age of 56 ± 15 years. No significant differences were observed between these groups with respect to any analyzed clinical characteristics. The technical success rates in the NDCDVP and DCDVP groups were 96.4 and 98.2%, respectively (P > 0.05). In the NDCDVP group, the small saphenous vein (SSV)or great saphenous vein (GSV)were the most common access routes (77.1%, 64/83), whereas the anterior tibial vein (ATV) was the most common access route in the DCDVP group (78.0%, 380/487), followed by the posterior tibial vein (PTV) and peroneal vein (PV)(15.6% and 6.4%, respectively). Relative to the NDCDVP group, more patients in the DCDVP group underwent the removal of deep vein clots below the knee (7.2% [6/83] vs. 24.2% [118/487], P < 0.001). Moreover, relative to the NDCDVP group, significantly lower complication rates were evident in the DCDVP group (local infection: 10.8% vs. 0.4%, P < 0.001; local hematoma: 15.7% vs. 1.0%, P < 0.001). The position change rate was also significantly lower in the DCDVP group relative to the NDCDVP group (0% [0/487] vs. 60.2% [50/83], P < 0.001). The calf deep veins (CDVs) represent a feasible and safe access route for the endovascular treatment of lower extremity deep vein thrombosis.

Effect of Acute Dietary Nitrate Supplementation on the Changes in Calf Venous Volume during Postural Change and Skeletal Muscle Pump Activity in Healthy Young Adults.

Dietary nitrate (NO3-) supplementation is known to enhance nitric oxide (NO) activity and acts as a vasodilator. In this randomized crossover study, we investigated the effect of inorganic NO3- supplementation on the changes in calf venous volume during postural change and subsequent skeletal muscle pump activity. Fifteen healthy young adults were assigned to receive beetroot juice (BRJ) or a NO3--depleted control beverage (prune juice: CON). Two hours after beverage consumption, the changes in the right calf volume during postural change from supine to upright and a subsequent right tiptoe maneuver were measured using venous occlusion plethysmography. The increase in calf volume from the supine to upright position (total venous volume [VV]) and the decrease in calf volume during the right tiptoe maneuver (venous ejection volume [Ve]) were calculated. Plasma NO3- concentration was higher in the BRJ group than in the CON group 2 h after beverage intake (p < 0.05). However, VV and Ve did not differ between CON and BRJ. These results suggest that acute intake of BRJ may enhance NO activity via the NO3- → nitrite → NO pathway but does not change calf venous pooling due to a postural change or the calf venous return due to skeletal muscle pump activity in healthy young adults.

A case of vitiligo that followed the path of a varicose vein in the lower leg.

Vitiligo is an acquired chronic depigmenting disorder of the skin and is characterized by the destruction of melanocytes. One of the clinical features of vitiligo is that damage to normal skin frequently results in the formation of depigmented macules, which is known as Köebner's phenomenon (KP). Here, we presented a case of vitiligo, in which depigmented macules followed the course of a dilated varicose vein. Dilatation of blood vessels was considered to contribute to the development of the vitiliginous lesions as a trigger for KP. Any kind of skin injury can trigger KP, but this is only the second case in which a dilated blood vessel caused KP in vitiligo. J. Med. Invest. 71 : 177-178, February, 2024.

Influence of Magnetic Field Strength on Intravoxel Incoherent Motion Parameters in Diffusion MRI of the Calf.

Background: The purpose of this study was to investigate the dependence of Intravoxel Incoherent Motion (IVIM) parameters measured in the human calf on B0. Methods: Diffusion-weighted image data of eight healthy volunteers were acquired using five b-values (0-600 s/mm2) at rest and after muscle activation at 0.55 and 7 T. The musculus gastrocnemius mediale (GM, activated) was assessed. The perfusion fraction f and diffusion coefficient D were determined using segmented fits. The dependence on field strength was assessed using Student's t-test for paired samples and the Wilcoxon signed-rank test. A biophysical model built on the three non-exchanging compartments of muscle, venous blood, and arterial blood was used to interpret the data using literature relaxation times. Results: The measured perfusion fraction of the GM was significantly lower at 7 T, both for the baseline measurement and after muscle activation. For 0.55 and 7 T, the mean f values were 7.59% and 3.63% at rest, and 14.03% and 6.92% after activation, respectively. The biophysical model estimations for the mean proton-density-weighted perfusion fraction were 3.37% and 6.50% for the non-activated and activated states, respectively. Conclusions: B0 may have a significant effect on the measured IVIM parameters. The blood relaxation times suggest that 7 T IVIM may be arterial-weighted whereas 0.55 T IVIM may exhibit an approximately equal weighting of arterial and venous blood.

Effect of passive leg raising on the cross-sectional area of the right internal jugular vein in patients with obesity: a randomised controlled trial protocol.

BACKGROUND: Venous access in patients with obesity presents significant challenges. The success of central venous catheterisation largely depends on the cross-sectional area (CSA) of the internal jugular vein (IJV). While techniques like the Trendelenburg position have been traditionally used to increase IJV CSA, recent studies suggest its ineffectiveness in patients with obesity. Conversely, the potential of the effect of passive leg raising (PLR) has not been thoroughly investigated in this group of patients. METHODS: This protocol outlines a planned randomised controlled trial to evaluate the effect of PLR on the CSA of the IJV in patients with obesity slated for central venous catheterisation. The protocol involves dividing 40 participants into two groups: one undergoing PLR and another serving as a control group without positional change. The protocol specifies measuring the CSA of the IJV via ultrasound as the primary outcome. Secondary outcomes will include the success rates of right IJV cannulation. The proposed statistical approach includes the use of t-tests to compare the changes in CSA between the two groups, with a significance threshold set at p<0.05. ETHICS APPROVAL: This study has been approved by the Institutional Review Board of Shanghai Tongren Hospital. All the participants will provide informed consent prior to enrolment in the study. Regarding the dissemination of research findings, we plan to share the results through academic conferences and peer-reviewed publications. Additionally, we will communicate our findings to the public and professional communities, including patient advocacy groups. TRIAL REGISTRATION NUMBER: ChiCTR: ChiCTR2400080513.

Convolutional Neural Networks to Study Contrast-Enhanced Magnetic Resonance Imaging-Based Skeletal Calf Muscle Perfusion in Peripheral Artery Disease.

Peripheral artery disease (PAD) is associated with impaired blood flow in the lower extremities and histopathologic changes of the skeletal calf muscles, resulting in abnormal microvascular perfusion. We studied the use of convolution neural networks (CNNs) to differentiate patients with PAD from matched controls using perfusion pattern features from contrast-enhanced magnetic resonance imaging (CE-MRI) of the skeletal calf muscles. We acquired CE-MRI based skeletal calf muscle perfusion in 56 patients (36 patients with PAD and 20 matched controls). Microvascular perfusion imaging was performed after reactive hyperemia at the midcalf level, with a temporal resolution of 409 ms. We analyzed perfusion scans up to 2 minutes indexed from the local precontrast arrival time frame. Skeletal calf muscles, including the anterior muscle, lateral muscle, deep posterior muscle group, and the soleus and gastrocnemius muscles, were segmented semiautomatically. Segmented muscles were represented as 3-dimensional Digital Imaging and Communications in Medicine stacks of CE-MRI perfusion scans for deep learning (DL) analysis. We tested several CNN models for the 3-dimensional CE-MRI perfusion stacks to classify patients with PAD from matched controls. A total of 2 of the best performing CNNs (resNet and divNet) were selected to develop the final classification model. A peak accuracy of 75% was obtained for resNet and divNet. Specificity was 80% and 94% for resNet and divNet, respectively. In conclusion, DL using CNNs and CE-MRI skeletal calf muscle perfusion can discriminate patients with PAD from matched controls. DL methods may be of interest for the study of PAD.

Exercise-induced calf muscle hyperemia quantified with dynamic blood oxygen level-dependent (BOLD) imaging.

Muscle hyperemia in exercise is usually the combined result of increased cardiac output and local muscle vasodilation, with the latter reflecting muscle's capacity for increased blood perfusion to support exercise. In this study, we aim to quantify muscle's vasodilation capability with dynamic BOLD imaging. A deoxyhemoglobin-kinetics model is proposed to analyze dynamic BOLD signals acquired during exercise recovery, deriving a hyperemia index (HI) for a muscle group of interest. We demonstrated the method's validity with calf muscles of healthy subjects who performed plantar flexion for muscle stimulation. In a test with exercise load incrementally increasing from 0 to 16 lbs., gastrocnemius HI showed considerable variance among the 4 subjects, but with a consistent trend, i.e. low at light load (e.g. 0-6 lbs) and linearly increasing at heavy load. The high variability among different subjects was confirmed with the other 10 subjects who exercised with a same moderate load of 8 lbs., with coefficient of variance among subjects' medial gastrocnemius 87.8%, lateral gastrocnemius 111.8% and soleus 132.3%. These findings align with the fact that intensive exercise induces high muscle hyperemia, but a comparison among different subjects is hard to make, presumably due to the subjects' different rate of oxygen utilization. For the same 10 subjects who exercised with load of 8 lbs., we also performed dynamic contrast enhanced (DCE) MRI to measure muscle perfusion (F). With a moderate correlation of 0.654, HI and F displayed three distinctive responses of calf muscles: soleus of all the subjects were in the cluster of low F and low HI, and gastrocnemius of most subjects had high F and either low or high HI. This finding suggests that parameter F encapsulates blood flow through vessels of all sizes, but BOLD-derived HI focuses on capillary flow and therefore is a more specific indicator of muscle vasodilation. In conclusion, the proposed hyperemia index has the potential of quantitatively assessing muscle vasodilation induced with exercise.

More potential uses of specific perforator flaps in the calf - A cadaveric study on the subdermal vascular structure of the lower leg.

BACKGROUND: The perforator flap has garnered significant interest since its inception due to its advantage of not needing a vascular network at the deep fascial level. Perforator flaps are commonly utilized in different flap transplant surgeries, and the thigh flap is presently the most widely used perforator flap. Is it possible for the calf to replace the thigh as a more suitable site for harvesting materials? Currently, there is a lack of relevant anatomical research. This study aims to address this question from an anatomical and imaging perspective. METHODS: This study used cadavers to observe the branches and courses of perforators on the calf and the distribution of skin branches using microdissection techniques, digital X-ray photography, and micro-computed tomography techniques. RESULTS: The perforators had three main branches: the vertical cutaneous branch, the oblique cutaneous branch, and the superficial fascial branch. The superficial fascial branch traveled in the superficial fascia and connected with the nearby perforators. The vertical and oblique cutaneous branches entered the subdermal layer and connected with each other to create the subdermal vascular network. CONCLUSIONS: We observed an intact calf cutaneous branch chain between the cutaneous nerve and the perforator of the infrapopliteal main artery at the superficial vein site. Utilizing this anatomical structure, the calfskin branch has the potential to serve as a substitute for thigh skin flap transplantation and may be applied to perforator flap transplantation in more locations.

Velocity-compensated intravoxel incoherent motion of the human calf muscle.

PURPOSE: To determine whether intravoxel incoherent motion (IVIM) describes the blood perfusion in muscles better, assuming pseudo diffusion (Bihan Model 1) or ballistic motion (Bihan Model 2). METHODS: IVIM parameters were measured in 18 healthy subjects with three different diffusion gradient time profiles (bipolar with two diffusion times and one with velocity compensation) and 17 b-values (0-600 s/mm2) at rest and after muscle activation. The diffusion coefficient, perfusion fraction, and pseudo-diffusion coefficient were estimated with a segmented fit in the gastrocnemius medialis (GM) and tibialis anterior (TA) muscles. RESULTS: Velocity-compensated gradients resulted in a decreased perfusion fraction (6.9% ± 1.4% vs. 4.4% ± 1.3% in the GM after activation) and pseudo-diffusion coefficient (0.069 ± 0.046 mm2/s vs. 0.014 ± 0.006 in the GM after activation) compared to the bipolar gradients with the longer diffusion encoding time. Increased diffusion coefficients, perfusion fractions, and pseudo-diffusion coefficients were observed in the GM after activation for all gradient profiles. However, the increase was significantly smaller for the velocity-compensated gradients. A diffusion time dependence was found for the pseudo-diffusion coefficient in the activated muscle. CONCLUSION: Velocity-compensated diffusion gradients significantly suppress the IVIM effect in the calf muscle, indicating that the ballistic limit is mostly reached, which is supported by the time dependence of the pseudo-diffusion coefficient.

Application of the ankle pump method in a sitting position to evaluate calf perforating veins by color Doppler ultrasound.

OBJECTIVE: We investigated the feasibility and efficacy of assessing calf perforating veins (PVs) using the ankle pump in a sitting position (AP-sit) method by color Doppler ultrasound. METHODS: We performed a multicenter prospective clinical trial between November 2022 and October 2023. Eligible patients with chronic venous disease and healthy controls were enrolled. The calf PVs were assessed using three different methods: manual compression in a standing position, manual compression in a sitting position, and AP-sit method. The reflux durations and detection rate of incompetent PVs (IPVs) were compared among the three methods. The number and diameter of calf PVs and distribution of IPVs were analyzed. RESULTS: A total of 50 patients with chronic venous disease and 50 healthy controls were included. There were 173 calves analyzed, including 97 healthy calves and 76 calves with chronic venous disease. The number of PVs per calf was higher in the diseased calves (median, 7.0; interquartile range [IQR], 6.0-8.0) than in the healthy calves (median, 5.0; IQR, 3.0-6.0; P < .001). The diameter of IPVs (median, 2.3 mm; IQR, 2.0-3.1 mm) was larger than that of competent PVs (median, 1.4 mm; IQR, 1.2-1.7 mm). Most of the IPVs (78.8%) were located in the medial and posterior middle of the calf. The reflux duration induced by the AP-sit method was greater than that induced by the manual compression methods (P < .001). Although the AP-sit method had a higher detection rate (92.0%) of IPVs than the manual compression methods (71.7% and 74.3% for standing and sitting, respectively; P < .001), especially in the distal lower leg, the manual compression methods found IPVs not found using the AP-sit method. CONCLUSIONS: Diseased calves with chronic venous disease have more PVs than do healthy calves. IPVs are commonly larger than competent PVs, with most IPVs located in the medial and posterior middle of the calf. Most importantly, the AP-sit method provides a convenient and effective approach for assessing the calf PVs, especially those located in the distal calf, as an alternative or complementary method to traditional manual compression, which is valuable in the daily practice of sonographers.