Artifact reduction of coaxial needles in magnetic resonance imaging-guided abdominal interventions at 1.5 T: a phantom study

Needle artifacts pose a major limitation for MRI-guided interventions, as they impact the visually perceived needle size and needle-to-target-distance. The objective of this agar liver phantom study was to establish an experimental basis to understand and reduce needle artifact formation during MRI-guided abdominal interventions. Using a vendor-specific prototype fluoroscopic T1-weighted gradient echo sequence with real-time multiplanar acquisition at 1.5 T, the influence of 6 parameters (flip angle, bandwidth, matrix, slice thickness, read-out direction, intervention angle relative to B0) on artifact formation of 4 different coaxial MR-compatible coaxial needles (Nitinol, 16G–22G) was investigated. As one parameter was modified, the others remained constant. For each individual parameter variation, 2 independent and blinded readers rated artifact diameters at 2 predefined positions (15 mm distance from the perceived needle tip and at 50% of the needle length). Differences between the experimental subgroups were assessed by Bonferroni-corrected non-parametric tests. Correlations between continuous variables were expressed by the Bravais–Pearson coefficient and interrater reliability was quantified using the intraclass classification coefficient. Needle artifact size increased gradually with increasing flip angles (p = 0.002) as well as increasing intervention angles (p < 0.001). Artifact diameters differed significantly between the chosen matrix sizes (p = 0.002) while modifying bandwidth, readout direction, and slice thickness showed no significant differences. Interrater reliability was high (intraclass correlation coefficient 0.776–0.910). To minimize needle artifacts in MRI-guided abdominal interventions while maintaining optimal visibility of the coaxial needle, we suggest medium-range flip angles and low intervention angles relative to B0.

A vibration sensor approach to detect intra-articular needle tip placement in the knee joint: a proof-of-concept study

Background Intra-articular injection in the dry knee joint is technically challenging particularly for the beginners. The aim of this study was to investigate the possible use of the vibration sensor to detect if the needle tip was at the knee intra-articular position by characterizing the frequency component of the vibration signal during empty syringe air injection. Methods Two milliliters of air were injected supero-laterally at extra- and intra-articular positions of a cadaveric knee joint, using needles of size 18, 21 and 24 gauge (G). Ultrasonography was used to confirm the positions of needle tip. A piezoelectric accelerometer was mounted medially on the knee joint to collect the vibration signals which were analyzed to characterize the frequency components of the signals during injections. Results The vibration frequency band power in the range of 500–1500 Hz was visually observed to potentially localize the needle tip placement during air injection whether they were at the knee extra-articular or intra-articular positions, as demonstrated by the higher band power (over − 40 dB or dB) for all the needle sizes. The differences of frequency band power between extra- and intra-articular positions were 18.1 dB, 26.4 dB and 39.2 dB for the needle size 18G, 21G and 24G respectively. The largest difference in spectral power was found in the smallest needle diameter (24G). Conclusions A vibration sensor approach was preliminarily proved to distinguish the intra-articular from extra-articular needle placement in the knee joint. This study demonstrated a possible implementation of an alternative electronic device based on this technique to detect the intra-articular knee injection.

Reinvestigation on Newer Facts to Anticipate, Avoid And Mitigate The Development of Post-Dural Puncture Headache-A Prospective Cohort Study

Purpose: Various researchers have described the size and the type of spinal needle used for neuraxial anesthesia as the most common risk factor for developing postdural puncture headache (PDPH). Even though the occurrence of the PDPH is rare in modern anesthesia practice, we come across many such patients despite following all guidelines or precautions. Patient-related factors for developing PDPH are relatively understudied. For that, clinical features commonly present in such patients may require a thorough investigation. Methods: This prospective cohort study included fifty patients admitted for lower extremities orthopedic surgeries and developed PDPH following the neuraxial blockade. We screened all patients in this study for the presence or absence of common manifestations suggestive of connective tissue disorders (CTD). The other outcomes, like the effect of spinal needle size/type to develop PDPH and time to develop PDPH, were also measured. Results: Almost all PDPH patients included in this study had common features suggestive of CTD: the ligamentous laxity (96%), high-arched palate (96%), the blue sclera (45%), joint hyperextensibility (82%), and ejection clicks (64%). PDPH occurred more frequently with the 25G spinal needle of Quincke type than 27G of Whitacre type (82% vs. 18%). The mean (SD) headache freedom time was 73.14 (24.74) hours. Conclusions: The CTD might also be a causative factor responsible for the development of PDPH in some individuals. It can be considered a risk factor to anticipate, avoid, and mitigate the development of PDPH.

Real-time measurement of intraocular pressure variation during automatic intravitreal injections: An ex-vivo experimental study using porcine eyes

Purpose To measure needle insertion force and change in intraocular pressure (IOP) in real-time during intravitreal injection (IVI). The effects of needle size, insertion speed, and injection rate to IOP change were investigated. Methods Needle insertion and fluid injection were performed on 90 porcine eyeballs using an automatic IVI device. The IVI conditions were divided according to needle sizes of 27-gauge (G), 30G, and 33G; insertion speeds of 1, 2, and 5 mm/s; and injection rates of 0.01, 0.02, and 0.05 mL/s. Insertion force and IOP were measured in real-time using a force sensor and a pressure transducer. Results The peak IOP was observed when the needle penetrated the sclera; the average IOP elevation was 96.3, 67.1, and 59.4 mmHg for 27G, 30G, and 33G needles, respectively. An increase in insertion speed caused IOP elevation at the moment of penetration, but this effect was reduced as needle size decreased: 109.8–85.9 mmHg in 27G for 5–1 mm/s (p = 0.0149) and 61.8–60.7 mmHg in 33G for 5–1 mm/s (p = 0.8979). Injection speed was also related to IOP elevation during the stage of drug injection: 16.65 and 11.78 mmHg for injection rates of 0.05 and 0.01 mL/s (p < 0.001). Conclusion The presented data offers an understanding of IOP changes during each step of IVI. Slow needle insertion can reduce IOP elevation when using a 27G needle. Further, the injection rate must be kept low to avoid IOP elevations during the injection stage.

Mixed Convection Flow Along Vertical Thin Needles Containing Gyrotactic Microorganism with Variable Heat, Mass and Motile Microorganism Flux

The problem of steady laminar mixed convection boundary layer flow along vertical thin needle with variable surface heat, mass and motile microorganism flux in the presence of gyrotactic microorganism is considered in this study. The dimensionless leading equations of continuity, momentum, concentraton and motile microorganism conservation are reduced to ordinary differential equations with the help of similarity transformations. The transformed governing equations are then numerically solved by using MATLAB BVP4C function. The research is reached to excellent argument by comparison in few cases between the results obtained from MATLAB and Maple algorithm with the help of dsolve command. Numerical calculations are carried out for various values of the dimensionless parameters of the problem which includes mixed convection parameter λ, power law index m, buoyancy parameters N1, N2 Lewis parameter Le, bioconvection lewis parameter Lb, Bioconvection peclet number Pe and also the parameter a representing the needle size. It is also shown from the results that the surface (wall) temperature, surface fluid concentration, surface motile microorganism concentration and the corresponding velocity, temperature, concentration and motile microorganism profiles are significantly induced by these parameters. The results are pictured and discussed in detail.

The Effect of Different Concentration of Aqueous Extracts of Labisia pumila in Preventing Osteoporosis and Improvement of Dermal Elasticity in Polycystic Ovary Syndrome Rats

Background: Labisia pumila (LP) a Malaysian herb thought to have phytoestrogenic effects in rats with PCOS. In this study we investigate the effects of LP aqueous extracts on bone composition, bone biomarkers and metabolic disorder in female rats fed continuously with high fat diet to induce PCOS. Hypothesis: The administration of Labisia pumila treatment in PCOS rats for 90 days will ameliorate the adverse effect of osteoporosis by reducing the inflammatory cytokine and improving the dermal elasticity of PCOS rats. Study design: On the 90th day of the development of PCOS model rats fed with high fat diet and after the vaginal smear analysis indicating a prolonged estrus cycle of more than 2 weeks, all PCOS rats were divided into 4 groups which consisted of control, placebo (water), LP25 (LP 25mg/kg) and LP50 (LP 50 mg/kg) respectively. All PCOS continue to received the formulated high fat diet and control animals continued to received normal chow and water ad libitum. Method: Vehicle and treatments, which were given orally by using stomach gavaging needle size 16 gauge straight and curve retrolingual administration. The rats were sacrificed at the end of the trial phase and organs, tissues and blood samples were harvested for multiple assays and analysis listed below.Results: The level of estradiol was significantly increased in LP25 and LP50 as compared with placebo. The inflammatory cytokine of C-reactive protein and TNF-ɑ were significantly decreased in LP25 and LP50.Conclusion: Treatment of LP extract might reduce the inflammatory cytokine related to the formation of osteoporosis and loss of bone mass, increase the insulin sensitivity and reduce of osteoporosis in PCOS patients. The phytoestrogenic of LP all of the above significant positive results are proven in lowering osteoporosis and metabolic disorder in PCOS rats.