Evaluation of Local Vascular Perfusion in the Lower Extremities on Intravoxel Incoherent Motion Imaging before and after Endovascular Therapy.

PURPOSE: To evaluate improvement in local vascular perfusion of the lower limbs on intravoxel incoherent motion (IVIM) imaging after endovascular therapy (EVT). MATERIALS AND METHODS: IVIM imaging was performed on 20 lower limbs of 16 patients with lower extremity arterial diseases before and after EVT. To estimate IVIM, diffusion-weighted lower-limb axial images (number of slices = 25 and slice thickness = 3.5 mm) were acquired using different b values (0, 300, and 1000 s/mm2). IVIM imaging with the simplified IVIM techniques was performed. The perfusion-related coefficient (D* [10-3 mm2/s]), perfusion fraction (f [%]), and D*f product (10-3 mm2/s %) were calculated before and 2-3 days after EVT. The ankle brachial index (ABI), mean D* (10-3 mm2/s), mean f (%), and mean D*f product (10-3 mm2/s %) before and after EVT were compared. RESULTS: Successful revascularization was achieved in all cases. After EVT, the mean ABI significantly increased from 0.59 ± 0.19 to 0.87 ± 0.15 (p < 0.001, paired t test). The mean D* (10-3 mm2/s) (22.08 ± 3.26 versus 24.87 ± 2.65, p = 0.005, paired t test), and D*f product (10-3 mm2/s%) (551.03 ± 79.02 versus 634.55 ± 76.96, p = 0.002, paired t-test) of the lower limbs significantly increased after EVT, whereas f (%) (25.00 ± 1.28 versus 25.52 ± 1.61, p = 0.261, paired t-test) did not significantly increased after EVT. CONCLUSION: D* (10-3 mm2/s) and D*f product (10-3 mm2/s %) on IVIM imaging could evaluate improvement in local vascular perfusion of the lower limbs after EVT. LEVEL OF EVIDENCE: Level 4, Case Series.

Pharmacokinetic/pharmacodynamic analysis of vancomycin in patients with Enterococcus faecium bacteraemia: a retrospective cohort study.

OBJECTIVES: The trough concentration of vancomycin and the area under the concentration-time curve (AUC)/minimum inhibitory concentration (MIC) ratio are crucial in determining vancomycin efficacy against methicillin-resistant Staphylococcus aureus. However, the use of similar pharmacokinetic principles in determining antibiotic efficacy against other gram-positive cocci is lacking. We performed a pharmacokinetic/pharmacodynamic analysis (association of target trough concentration values and AUC/MIC with therapeutic outcome) of vancomycin in patients with Enterococcus faecium bacteraemia. METHODS: Between January 2014 and December 2021 we performed a retrospective cohort study of patients with E. faecium bacteraemia treated with vancomycin. Patients who received renal replacement therapy or had chronic kidney disease were excluded. Clinical failure, the primary outcome, was defined as a composite of 30-day all-cause mortality, vancomycin-susceptible infection requiring change of treatment, and/or recurrence. AUC24 was estimated using a Bayesian estimation approach based on an individual vancomycin trough concentration. The MIC for vancomycin was determined using a standardised agar dilution method. Additionally, classification was used to identify the vancomycin AUC24/MIC ratio associated with clinical failure. RESULTS: Of the 151 patients identified, 69 were enrolled. All MICs of vancomycin for E. faecium were ≤1.0 µg/mL. The AUC24 and AUC24/MIC ratio were not significantly different between the clinical failure group and the clinical success group (432±123 µg/mL/hour vs 488±92 µg/mL/hour; p=0.075). However, 7 of 12 patients (58.3%) in the clinical failure group and 49 of 57 patients (86.0%) in the clinical success group had a vancomycin AUC24/MIC ratio ≥389 (p=0.041). No significant association between trough concentration or AUC24 ≥600 µg/mL×hour and acute kidney injury was observed (p=0.365 and p=0.487, respectively). CONCLUSION: The AUC24/MIC ratio is associated with the clinical outcome of vancomycin administration in E. faecium bacteraemia. In Japan, where vancomycin-resistant enterococcal infection is rare, empirical therapy with a target AUC24 ≥389 should be recommended.

Three-dimensional velocity vector image obtained via 4-dimensional flow magnetic resonance imaging for in-stent flow visualization in the superficial femoral artery.

The assessment of stent lumen patency via non-contrast-enhanced 2-dimensional time-of-flight magnetic resonance angiography (2D TOF MRA) is complex due to stent-related artifacts. However, an imaging technique using the phase-contrast method, which can reduce susceptibility to artifact, is available. Herein, we report the use of 3-dimensional velocity vector image obtained via 4-dimensional flow magnetic resonance imaging (4D flow MRI) for in-stent flow visualization after stent development in the right superficial femoral artery. Hence, instead of 2D TOF MRA, 4D flow MRI using the phase-contrast method can be performed to assess stent lumen patency as it reduces stent-related artifacts.

Effects of angiotensin II receptor blockers on serum potassium level and hyperkalemia risk: retrospective single-centre analysis.

OBJECTIVE: To examine the effect of angiotensin II receptor blocker (ARB) treatment on serum potassium level and hyperkalaemia risk in a clinical setting with inpatients and outpatients using calcium channel blockers (CCBs) as a reference standard. METHODS: The increased risk of hyperkalaemia associated with ARB treatment is known, however only a few studies have used an active comparator to examine this risk. In this retrospective study at a 320-bed general hospital in Japan, the hospital information system was used to identify patients with at least one prescription for an ARB (819 patients) or a CCB (1015 patients) who were naive to these drugs before study initiation. Serum potassium levels before and after ARB treatment were compared. Additionally, the unadjusted and adjusted hazard ratios for the risk of hyperkalaemia in the ARB and CCB users were estimated. RESULTS: The serum potassium level was higher in patients receiving ARB treatment (0.05 mEq/L, p=0.02) compared with those on CCB treatment. However, there was no significant association between ARB use and hyperkalaemia (adjusted HR 0.91, 95% CI 0.42 to 1.99, p=0.82). CONCLUSION: The increase in serum potassium level after ARB initiation makes it necessary to monitor serum potassium levels continuously during ARB treatment; however, the risk of hyperkalaemia appeared to be similar for ARB and CCB treatments.

Improvement in local vascular perfusion of the lower extremities on intravoxel incoherent motion imaging: A case report.

Intravoxel incoherent motion imaging has its improvement-evaluating ability in lower limb perfusion after endovascular therapy in individuals with lower extremity arterial disease. Here, we present a 70-year-old man with intermittent claudication of the left lower limb, whose microperfusion on intravoxel incoherent motion imaging improved after endovascular therapy. The patient underwent intravoxel incoherent motion imaging of the lower extremities pre- and postendovascular therapy. After endovascular therapy, the left ankle brachial index increased from 0.46 to 1.06. The mean perfusion-related coefficient (10-3 mm2/s) of the left lower limb increased from 19.70 ± 3.17 to 24.81 ± 3.41, and mean perfusion fraction (%) of the left lower limb slightly increased from 24.41 ± 0.96% to 25.20 ± 1.89% after endovascular therapy. Therefore, successful revascularization can improve microperfusion on intravoxel incoherent motion imaging in a patient with lower extremity arterial disease.