Calcium-Free Dialysate Hemodialysis: A Simplified Approach.

Intermittent hemodialysis (HD) in high-bleeding-risk patients presents a challenge as circuit anticoagulation using heparin is contraindicated in such cases. Recently, the use of calcium-free citrate-containing dialysate with calcium supplementation emerged as a viable alternative to heparin-circuit anticoagulation. This is a retrospective, monocentric study to evaluate dialysis efficacy using calcium-free citrate-containing dialysate with calcium reinjection into the venous line in hemodialysis patients at risk of bleeding. A total of 53 patients were analyzed: 52 had a temporary contraindication to systemic anticoagulation (active bleeding or surgical intervention), and 1 chronic HD patient had prolonged bleeding time due to inoperable arteriovenous fistula stenosis. Only 7 out of 79 dialysis sessions performed were prematurely terminated (vascular access dysfunction). The median dialysis time was 240 min (range: 150-300). The chronic dialysis patient had 108 sessions with no premature termination. Frequent monitoring of ionized calcium was performed throughout the dialysis sessions: levels remained stable at T0 and T + 60 min (1.08 ± 0.08 mmol/L) and slightly increased at the end of the dialysis session (1.19 ± 0.13 mmol/L), remaining within normal limits. Target postfilter ionized calcium <0.4 mmol/L was achieved in all sessions (0.31 ± 0.07 mmol/L). There were no cases of symptomatic hypo-/hypercalcemia and no need for calcium infusion rate adjustment throughout the sessions. Hemodialysis with calcium-free citrate-containing dialysate and calcium reinjection into the venous line is efficient and safe in HD patients with contraindications to systemic anticoagulation.

On the benefits of desulfated seawater flooding in mature hydrocarbon fields.

Removal of sulfate from the injection seawater (desulfation) in hydrocarbon reservoirs is a Modified Salinity Water (MSW) flooding method that mitigates microbial reservoir souring, improves oil recovery, and enables produced-water re-injection (PWRI). Aside from the Improved Oil Recovery (IOR) effect, desulfation results in a cleaner production of oil through enabling PWRI and reducing the environmental impacts associated with reservoir souring and nitrate treatment. However, whether desulfation is still beneficial for mature fields, after years of the injection of untreated seawater, is a valid common concern. In such cases, sulfate concentration inside the reservoir has already increased due to years of untreated seawater injection. The high sulfate concentration inside the subsurface reservoir before desulfated water flooding may render desulfation pointless. The present study investigates the potential benefits of desulfation after around 20 years of untreated seawater injection in a sector of an oil field in the Danish North Sea. The results show that depending on the cessation of production point in time and the efficiency of residual oil saturation reduction of MSW flooding, desulfation results in a significant increase in oil production. Even if improving oil recovery is no longer a priority, modification of injected seawater would still help reduce the amount of water required to support a given oil production rate. Moreover, desulfation is considerably more effective than nitrate treatment in mitigating microbial reservoir souring. Furthermore, the possibility of scale formation is decreased considerably due to desulfation, which further encourages PWRI.

Experimental Investigation of Polymer Injection in High Permeability Conduits for Material Sustainability and Behavior in Oil Reservoirs.

Polymers are one of the most widely used chemicals in the oil and gas industry. They are used for mobility control in enhanced oil recovery, in conformance control as a cross-linked plugging agent, as a fracking fluid for fracture propagation and proppant transportation, and in drilling fluids as an additive for drilling mud enhancement. This research characterizes the polymer injectivity in different pore sizes under different conditions and evaluates the polymer conditions after injection. Based on this, the ability to reinject the polymer in the porous media is discussed. The factors studied include the pore size, the polymer concentration, the polymer injection flowrate, and polymer injectivity. When the porous media size was reduced to 1.59 mm (1/16th of an inch), the injectivity value reduced significantly, reaching less than 0.2 mL/min/psi and the polymer degradation increased primarily due to shearing. Results also showed that the polymers underwent four main degradations during injection including dehydration, syneresis, shearing, and excessive hydrolysis. In continuous fractures, the degradation is a strong function of the fracture size, length, and the polymer structure. The experimental results showed that one or more of the polymer degradations resulted in the inability to reinject the polymer in most cases.

Can late lymphoscintigraphy be omitted in the sentinel node procedure in early-stage vulvar cancer?

INTRODUCTION: In the Netherlands, the sentinel lymph node procedure protocol consists of preoperative lymphoscintigraphy combined with intraoperative blue dye for identifying sentinel lymph nodes in early vulvar squamous cell carcinoma. This study aimed at investigating the role of early and late lymphoscintigraphy. MATERIAL AND METHODS: From January 2015 to January 2019, early and late lymphoscintigraphies of 52 women were retrospectively analyzed. Lymphoscintigraphy was performed 30 minutes (early) and 2.5-4 hours (late) after vulvar injection of 99m Tc-labeled nanocolloid. We calculated the concordance correlation coefficient (CCC) between number of sentinel lymph nodes detected on both images using the Lins concordance coefficient and correlated with clinicopathological data. RESULTS: Thirty-four women had a midline tumor and 18 had a lateral tumor. Detection rates with early and late scintigraphy were 88.5% and 98.1%, respectively. Median number of detected nodes was 1.0 (0-7) and 2.0 (0-7). Good statistical correlation between number of sentinel lymph nodes detected on early and late imaging was found (CCC = 0.76) in most patients. In 18 women (35%) a mismatch occurred: a higher number of nodes was detected on late imaging. In 11 of 18 women re-injection was performed because no sentinel lymph nodes were visualized on early images. Late imaging and intraoperative detection showed a good statistical correlation (CCC = 0.61). One woman showed an isolated groin recurrence despite negative sentinel lymph nodes. CONCLUSIONS: This study showed good statistical correlations between early and late scintigraphy in most patients. However, in 35% of women late scintigraphy detected more nodes. In case of poor visualization after the first scintigraphy, re-injection should be considered. Late scintigraphy is probably helpful in confirming successful re-injection and in showing deviating lymph flow in women with failed mapping after the first injection and successful re-injection. Because missing metastatic sentinel lymph nodes often leads to a poor prognosis, we prefer optimal correlations between imaging and intraoperative identification. Hence, late scintigraphy cannot be safely omitted.

Bacterial and Archaeal Community Distribution in Oilfield Water Re-injection Facilities and the Influences from Microorganisms in Injected Water.

Water flooding is widely employed for oil production worldwide. However, there has never been a systematic investigation of the microbial communities occurring in oilfield water re-injection facilities. Here, we investigated the distribution of bacterial and archaeal communities in water re-injection facilities of an oilfield, and illustrated the combined influences of environmental variation and the microorganisms in injected water on the microbial communities. Bacterial communities from the surface injection facilities were dominated by aerobic or facultative anaerobic Betaproteobacteria, Alphaproteobacteria, and Flavobacteria, whereas Clostridia, Deltaproteobacteria, Anaerolineae, and Synergistia predominated in downhole of the injection wells, and Gammaproteobacteria, Betaproteobacteria, and Epsilonproteobacteria predominated in the production wells. Methanosaeta, Methanobacterium, and Methanolinea were dominant archaea in the injection facilities, while Methanosaeta, Methanomethylovorans, and Methanoculleus predominated in the production wells. This study also demonstrated that the microorganisms in injected water could be easily transferred from injection station to wellheads and downhole of injection wells, and environmental variation and diffusion-limited microbial transfer resulted from formation filtration were the main factors determining microbial community assembly in oil-bearing strata. The results provide novel information on the bacterial and archaeal communities and the underlying mechanisms occurring in oilfield water re-injection facilities, and benefit the development of effective microbiologically enhanced oil recovery and microbiologically prevented reservoir souring programs.

Cervical re-injection of indocyanine green to improve sentinel lymph node detection in endometrial cancer.

OBJECTIVES: To evaluate the role of cervical re-injection of indocyanine green (ICG) to increase the detection rate of sentinel lymph node (SLN) in patients with endometrial cancer (EC) who underwent robotic-assisted surgical staging. METHODS: We retrospectively identified consecutive EC patients undergoing robotic-assisted staging with SLN biopsy at our Institution between June 2016 and April 2020. Patients were excluded if they had open abdominal surgical approach, neoadjuvant chemotherapy, and advanced stage [International Federation of Gynecology and Obstetrics (FIGO) stage III-IV] at diagnosis. According to our SLN protocol, in case of either unilateral or no SLN detection, we performed an ipsilateral or bilateral cervical re-injection of ICG. RESULTS: In total, 251 patients meeting inclusion criteria were included in the analysis. At first injection, bilateral detection was achieved in 184 (73.3%), unilateral detection in 57 (22.7%), and no detection in 10 (4.0%) patients. Cervical re-injection was performed in 51 of 67 patients with failed bilateral mapping. After cervical re-injection, bilateral detection rate increased to 94.5% (222/235), while unilateral and no detection were 5.1% (12/235) and 0.4% (1/235), respectively. CONCLUSIONS: Our results suggest that cervical re-injection of ICG, in case of failed bilateral mapping of SLN, brings about a significant improvement in SLN detection rates, therefore reducing the number of side-specific required lymphadenectomies.

Reinjection flow field-flow fractionation method for nanoparticle quantitative analysis in unknown and complex samples.

An analytical challenge that arises in environmental and food analysis is to quantify heterogeneous nanoparticles especially in polydisperse and complex samples. The method stated herein based on the reinjection asymmetrical flow field-flow fractionation (AF4 × AF4) coupled with inductively coupled plasma-mass spectrometer (ICP-MS) and statistical deconvolution allowed for identifying the molecular weight (Mw) and selenium abundance of the low Mw protein fractions (ca. < 132 kDa) in an unknown and complex sample (e.g., selenium-rich soybean protein isolates (Se-SPI)). A non-linear decay crossflow program was also developed to get better resolution and shorter elution time for both low and high Mw components. The concept of the reinjection method was based on the excellent ability for reducing sample complexity regarding the size fractionation, and peak reproducibility under the identical conditions of AF4 system. The standard protein mixture was used as a proof-of-principle sample. The results showed the underlying peaks predicted by the reinjection method were agreed with the separation result using the standard mixture (the relative standard deviation of peak locations < 1%), which indicated the reinjection method could provide an accurate assessment of the underlying peak number and location, and was promising to minimize the overfitting problem for statistic deconvolution. Interestingly, significant differences of Se abundance in protein fractions were observed in the low Mw range for Se-SPI, ranging from 0.28 to 1.66 cps/V with the Mw ranging from 13.75 kDa to 104.17 kDa, which indicated significant differences in the ability of binding Se for these selenium-rich proteins in Se-SPI.

Physicochemical and biological controls of sulfide accumulation in a high temperature oil reservoir.

In order to maintain the reservoir pressure during secondary oil production large volumes of seawater are injected into reservoirs. This practice introduces high concentrations of sulfate into the reservoir promoting the growth of sulfate-reducing microorganisms (SRM) and results in the production of an increasing volume of produced water (PW) that needs to be discharged. SRM reduce sulfate to sulfide causing reservoir souring and as a mitigation strategy nitrate is injecting along with the seawater into the reservoir. We used PW from the Halfdan oil field (North Sea) to set up microcosms to determine the best reinjection strategy in order to inhibit SRM activity and minimize the environmental impact of PW during secondary oil production. We discuss the effect of temperature, electron donor, and sulfate and nitrate availability on sulfide production and microbial community composition. Temperature and the terminal electron acceptor played a key role in shaping the microbial community of the microcosms. PW reinjection at 62 °C inhibited SRM activity due to nitrite toxicity by encouraging nitrate reduction to nitrite by thermophilic nitrate reducers, while at 74 °C we observed complete absence of any microbial activity over the course of 150 days. KEY POINTS: • Temperature and the presence/ absence of nitrate shaped the microbial community structure. • Thermophilic nitrate reducers convert nitrate to ammonia with the accumulation of nitrite that inhibits sulfide production. • Nitrite inhibition is the most effective nitrate-based souring mitigation mechanisms. • The reinjection of hot produced water to oil reservoirs is a promising souring mitigation approach.

Occurrence of antibiotic resistance genes in an oilfield's water re-injection systems.

The recent widespread increase in antibiotic resistance has become a real threat to both human and environmental ecosystem health. In oil reservoirs, an extreme environment potentially influenced by human activity such as water flooding, the distribution and abundance of antibiotic resistance genes (ARGs) remains poorly understood. Herein, we investigated the distribution of ARGs at different positions in a water-flooding oilfield in China, and found that ARGs were observed in all parts of the investigated system. The surface regions of the water re-injection system were more vulnerable to ARG pollution, and the final ARG concentration was up to 2.2 × 108 gene copies/L, and sulfonamide were the most abundant. However, ARG concentration decreased sharply in the samples from underground part of the re-injection system. The bacterial community composition was also varied with sampling position. The sample from production well, which was enriched in crude oil, contained more bacteria but the community richness was simpler. This study also indicated the wastewater-recycling process above ground, which proposed to reduce the discharge into environment directly, may pose a risk for ARGs spread.

A Comparison Study of Ranibizumab and Aflibercept in Patients with Naive Diabetic Macular Edema in Presence of Serous Retinal Detachment.

Aim of the study: The aim of this study is to compare the efficacy of intravitreal injection of Aflibercept and Ranibizumab in the treatment of naive diabetic macular edema (DME) with serous retinal detachment (SRD). Materials and methods: In this prospective, non-randomized-cohort study, 60 eyes with DME with SRD were divided into 2 groups: group 1 consisted of 30 eyes treated with intravitreal injection of 0.5 mg/0.1 mL Ranibizumab (IVR) and group 2 consisted of 30 eyes treated with intravitreal injection of 2 mg/0.05 mL Aflibercept (IVA). After three sequential injections with 30-40-day interval as a loading dose, all patients were followed up for 12 months. The best-corrected visual acuity (BCVA), central macular thickness (CMT), SRD's height (SRDH) and the number of reinjections of the drugs were compared. Results: The groups were similar in terms of age and sex (p > 0.05). There was no difference between groups in terms of the baseline BCVA, CMT and SRDH (p > 0.05). There was no significant difference between groups with regard to BCVA and CMT values for 12 months (p > 0.05). SRDH decreased significantly in both groups; however, the reduction of SRDH was considerably higher in group 2 for 12 months (p < 0.05). The mean number of reinjection was 4.40 ± 0.85 in group 1 and 3.16 ± 0.75 in group 2 and it was noticeably lower in group 2 (p < 0.001). The number of cases with persistent SRD at the end of the study was 14 (46.6%) in group 1 and 5 (16.6%) in group 2 (p < 0.001). Conclusions: Aflibercept may treat SRD more efficiently in patients with DME compared to Ranibizumab with fewer injections.

[Graft reinjection: Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]. / Réinjection du greffon : recommandations de la Société francophone de greffe de moelle et de thérapie cellulaire (SFGM-TC).

JACIE (Joint Accreditation Committee ISTC EBMT) regulations and standards impose a quality and safety requirement for graft reinjection by nurses. However, the standards do not provide a step-by-step graft reinjection procedure. Because of high medical team turnover, the opening of new transplant centers, and continual questions from colleagues trying to decipher the JACIE standards, the need for a specific procedure goes without saying. We collected graft reinjection procedures from each SFGM-TC center that participated in our survey, thus creating an inventory of the different steps that make up graft reinjection. In addition to reviewing the main regulatory texts and JACIE standards, we sought advice from medical and cellular therapy experts. We observed that most centers use a mix of practices and some unjustified practices. In some transplant units, it is still standard practice to defrost cell therapy products in the transplant unit. Caregivers are aware of the need for a rigorous application of the regulatory requirements and are willing to administer a procedure that provides specific steps for each stage of the process. In this workshop, we questioned each stage of the graft reinjection procedure, which helped us define clear methods of implementation. In the form of a checklist, we offer bone marrow and stem cell transplant units a step-by-step procedure.

Effect of early use of AbobotulinumtoxinA after stroke on spasticity progression: Protocol for a randomised controlled pilot study in adult subjects with moderate to severe upper limb spasticity (ONTIME pilot).

INTRODUCTION: Approximately 15 million people suffer a stroke annually, up to 40% of which may develop spasticity, which can result in impaired limb function, pain and associated involuntary movements affecting motor control.Robust clinical data on spasticity progression, associated symptoms development and functional impairment is scarce. Additionally, maximal duration of muscle tone reduction following botulinum toxin type A (BoNT-A) injections remains undetermined. The ONTIME pilot study aims to explore these issues and evaluate whether abobotulinumtoxinA 500 U (Dysport®; Ipsen) administered intramuscularly within 12 weeks following stroke delays the appearance or progression of symptomatic (disabling) upper limb spasticity (ULS). METHODS: ONTIME is a 28-week, phase 4, randomised, double-blind, placebo-controlled, exploratory pilot study initiated at four centres across Malaysia, the Philippines, Singapore and Thailand. Subjects (n = 42) with moderate to severe ULS (modified Ashworth scale [MAS] score ≥2) in elbow flexors or pronators, wrist flexors, or finger flexors will be recruited. Subjects will be randomised 2:1 to abobotulinumtoxinA 500 U or placebo (single dose 2-12 weeks after first-ever stroke).Primary efficacy will be measured by time between initial injection and visit at which reinjection criteria (MAS score ≥2 in the primary targeted muscle group and appearance or reappearance of symptomatic ULS) are met. Follow-up visits will be 4-weekly to a maximum of 28 weeks. DISCUSSION: This pilot study will facilitate the design and sample size calculation of further confirmatory studies, and is expected to provide insights into the optimal management of post-stroke patients, including timing of BoNT-A therapy and follow-up duration.

Evaluation of conditions of comprehensive two-dimensional gas chromatography that yield a near-theoretical maximum in peak capacity gain.

The peak capacity gain (Gn) of a GC×GC system is the ratio of the system peak capacity to that of an optimized one-dimensional GC analysis lasting the same time and providing the same detection limit. A near-theoretical maximum in Gn has been experimentally demonstrated in GC×GC-TOF based on a 60m×0.25mm primary column. It was found that Gn was close to 9 compared to the theoretical maximum of about 11 for this system. A six-sigma peak capacity of 4500 was obtained during an 80min heating ramp from 50°C to 320°C. Using peak deconvolution, 2242 individual peaks were determined in a Las Vegas runoff water sample. This is the first definitive experimental demonstration known to us of an order-of-magnitude Gn. The key factors enabling this gain were: relatively sharp (about 20ms at half height) reinjection pulses into the secondary column, relatively long (60m) primary column, the same diameters in primary and secondary columns, relatively low retention factor at the end of the secondary analysis (k≅5 instead of 15, optimal for ideal conditions), optimum flow rate in both columns, and helium (rather than hydrogen) used as the carrier gas. The latter, while making the analysis 65% longer than if using H2, was a better match to the reinjection bandwidth and cycle time.

Effects of core vitrectomy in the treatment of age-related macular degeneration.

PURPOSE: To investigate the clinical efficacy and safety of an additional core vitrectomy to the standard therapy in patients with exudative age-related macular degeneration (ARMD). METHODS: In this prospective, controlled, single-centre study, 50 eyes of 50 patients (mean age: 74.1 ± 7.1; median 74 (69/78)) with ARMD were enrolled and randomized 1:1 to group 1 - core vitrectomy additional to three times injections of ranibizumab (3x Rbz) and Group 2 - 3x Rbz (control). 1 16 of 25 eyes in Group 1(64%) and 12 of 25 (48%) in Group 2 had a posterior vitreous detachment (PVD) prior to start of the study. Changes in best-corrected visual acuity (BCVA) using ETDRS charts, central macular thickness and macular volume (OCT) as well as the rate of reinjection with an OCT-based pro renata (PRN) protocol were monitored prospectively over 48 weeks. Forty-seven eyes completed follow-up at week 48. RESULTS: In Group 1, 4 of 24 lost 1 line of BCVA (16.7%) and 3 of 24 lost 2 lines (12.5%), whereas 17 of 24 gained more than 1 line (70.8%) and improved in average by 9.8 letters. In Group 2, 3 of 23 remained stable and 20 of 23 gained more than or exactly 1 line (78.3%), resulting in 14.3 letters, with no loss of lines. Central macular thickness decreased by 85.58 µm (28.8%) in Group 1 and by 121.43 µm (32.68%) in Group 2 compared with baseline. In Group 1, four patients received three additional and two patients, two additional Rbz injections. In Group 2, three patients received three additional, three patients two and 12 patients one additional Rbz injections. This yielded in an average injection rate of 3.66 in Group 1 and 4.17 in Group 2 over 48 weeks. Posterior vitreous detachment (PVD) was identified in Group 1 in 16 of 24 (66.7%) and in Group 2 in 12 of 23 (52.2%) patients at baseline. At week 48, 6 of 8 (75%) of the patients in Group 1 with initial attached vitreous showed a vitreal detachment, whereas only 1 of 11 (9%) in Group 2 had a new occurred detachment of the vitreous. No systemic or ocular adverse events were noticed. CONCLUSION: An initial core vitrectomy combined with a conventional ranibizumab injection regimen for exudative AMD patients was safe and lead to similar functional results with less intravitreal ranibizumab injections over 48 weeks.

Intravitreal Triamcinolone Reinjection for Refractory Diabetic Macular Edema

PURPOSE: To evaluate the effect of intravitreal triamcinolone acetonide (IVT) reinjection on clinical and optical coherence tomographic features in refractory diabetic macular edema. METHODS: In a prospective interventional case series, all IVT treated patients enrolled in a previous clinical trial were recalled to have a new ophthalmologic examination and optical coherence tomography (OCT) performed. Eyes found suitable for reinjection received 4 mg IVT. Complete clinical examination and OCT were repeated at 2 and 4 months post-injection. The changes were statistically analyzed using a paired t test and were compared to the results of the first injections. RESULTS: Of all returning patients, 12 cases with complete records were considered candidates for reinjection. Visual acuity (VA) changes were not significant after the first and second interventions, although there was a relative improvement (0.14 logMAR) 2 months after the first injection. Reductions of central macular thickness (CMT) were 43+/-69 micrometer, and 40+/-69 micrometer after the first injection and 27+/-48 micrometer, 49+/-58 micrometer after the reinjection at 2 and 4 months, respectively. None of the mentioned changes was significant. After the second injection, however, intraocular pressure was elevated at both 2 and 4 months (3.6 and 2.4 mmHg respectively, P<0.05). Two months after the first administration, intraocular pressure was found to be raised significantly (5.58 mmHg, P=0.001). CONCLUSIONS: The transient beneficial effects of IVT on diabetic macular edema are not repeated with second injections. However, IVT-related ocular hypertension is more persistent after reinjection.

Role of Redistribution and 24 Hour Reinjection Images to assess Myocardial Viability in Patients with Acute Myocardial Infarction / 대한핵의학회잡지

PURPOSE: We evaluated the importance of redistribution and 24 hour reinjection images in Tl-201 SPECT assessment of myocardial viability after acute myocardial infarction (AMI). MATERIALS AND METHODS: We performed dipyridamole stress-4 hour redistribution-24 hour reinjection Tl-201 SPECT in 43 patients with recent AMI (4-16 days). The myocardium was divided into 16 segments and perfusion grade was measured visually with 4 point score from 0 to 3 (absent uptake to normal uptake). A perfusion defect with stress score 2 was considered moderate. A defect was considered severe if the stress score was 0 or l (absent uptake or severe perfusion decrease). Moderate defect on stress image were considered viable and segments with severe defect were considered viable if they showed improvement of 1 score or more on redistribution or reinjection images. We compared the results of viability assess-ment in stress-redistribution and stress-reinjection images. RESULTS: On visual analysis, 344 of 688 segments (50%) had abnormal perfusion. Fifty two (15%) had moderate perfusion defects and 292 (85%) had severe perfusion defects on stress image. Of 292 severe stress defects, 53 were irreversible on redistribution and reversible on reinjection images, and 15 were reversible on redistribution and irreversible on reinjection images. Two hundred twenty four of 292 segments (76.7%) showed concordant results on stress-redistribution and stress-reinjection images. Therefore 24 hour reinjection image changed viability status from necrotic to viable in 53 segments of 292 severe stress defect (18%). However, myocardial viability was underestimated in only 5% (15/292) of severe defects by 24 hour reinjection. CONCLUSION: The 24 hour reinjection imaging is useful in the assessment of rnyocardial viability. It is more sensitive than 4 hour redistribution imaging. However, both redistribution and reinjection images are needed since they complement each other.

Assessment of Viability in Regional Myocardium with Reversed Redistribution by Thallium Reinjection in Patients with Acute Myocardial Infarction / 대한핵의학회잡지

PURPOSE: The aim of this study was to evaluate whether T1-201 reinjection distinguishes viable from non-viable myocardium in patients with reverse redistribution after acute myocardial infarction. MATERIALS AND METHODS: We studied 42 patients with acute myocardial infarction (age, 55+/-12 years). Eighteen (43%) out of 42 showed reverse redistribution on dipyridamole stress-4 hour redistribution T1-201 single photon emission computed tomography (SPECT). T1-201 reinjection was performed at 24 hours. Reverse redistribution was defined as worsening of perfusion defect at 4 hour delayed scan. All patients underwent follow-up echocardiography in 4 months to assess regional wall motion improvement. T1-201 uptake on reinjection images were analyzed for the prediction of myocardial wall motion improvement. RESULTS: Of 36 segments with reverse redistribution, 17 segments showed normal wall motion on echocardiography, while 19 segments showed all motion abnormalities. Of 19 the segments with reverse redistribution, 11 (58%) showed enhanced uptake after 24 hour reinjection. Myocardial wall motion was improved in 10 of 11 segments (90%) with enhanced uptake on reinjection. Wall motion improvement was not seen in 5 of 8 segments (63%) without enhanced thallium uptake. When myocardial viability was assessed by the uptake on reinjection image, nine of 10 segments (90%) with normal or mildly decreased uptake showed improved wall motion. Wall motion was not improved in 5 of 9 segments (56%) with severely decreased uptake. CONCLUSION: In patients with acute myocardial ifarction, T1-201 reinjection imaging on myocardial segments with reverse redistribution has a high positive predictive value in the assessment of myocardial viability.

Role of 24-hr delayed imaging after reinjection for identification of viable myocardium in dipyridamole stress 201Tl myocardial SPECT

BACKGROUND: It was known that conventional stress-redistribution imaging was not adequate for detection of severely ischemic but viable myocardium. Albeit the gold criteria of viable myocardium is the presence of metabolism which can be detected by PET, reinjection technique was reported to be able to identify most, if not all, of viable myocardium. Because reinjection imaging is performed immediately after redistribution imaging, an additional redistribution could be happened if we follow the patient longer. To prove the guess authors performed an additional delayed imaging 24 hours after reinjection of 201T1. METHODS: Subject patients were 20 ischemic heart disease patients who showed irreversible perfusion defect(s) on standard pharmacologic(dipyridamole) stress-redistribution images. Immediately after the redistribution images were obtained, 37 MBq thallium was injected at rest, and images were reacquired at 10 minutes and 24 hours after reinjection. Four sets of images(stress, redistribution, reinjection and delayed images) were then analyzed qualitatively and quantitatively. Left ventricle was arbitrarily divided into 9 segments(apex, proximal and distal portions of anterior, septal, inferior and lateral walls). RESULTS: These were 45 irreversible perfusion defects in 20 subject patients, of which 21(46.7%) showed improved thallium uptake after reinjection. Among these 21 segments 2 demonstrated further improvement of uptake on 24-hour delayed images, of the 24 regions determined to have persistent defects after reinjection. 10(41.7%) showed improved uptake on delayed images. CONCLUSIONS: In addition to reinjection imaging, 24-hour delayed imaging after reinjection was also helpful to identify severely ischemic but viable myocardium.

Clinical Value of Thallium-201 Reinjection for the Identification of Myocardial Viability in Patients with Coronary Artery Disease and Left Ventricular Dysfunction

BACKGROUND: The reinjection of a small dose of thallium-201 after stress and delayed imaging often shows new redistribution in the region with persistent defect. The purpose of this study was to determine the incidence of incomplete redistribution on conventional delayed image and to compare the left venticular wall motion abnormality with myocardial viability in patients with coronary artery disease. METHODS: We studied 12 patients with chronic coronary artery disease, using exercise thallium-201 Single Photon Emission Tomopraphy(TI-201 SPECT) and coronary angiopraphy with contrast ventriculography. Patients received 2mCi of thallium intravenously during exercise, redistribution images were performd 4 hour late and a second dose of 1mCi of thallium was injected at rest immediately there after. The three sets of image(stress, redistribution and reinjection) were analyzed. The left ventricular myocardium was divided into 7 segments and regional wall motion was scored on scale from 2(normal) to -1(dyskinesis). RESULTS: 1) The redistribution was obtained in 42.9% of the segments with persistent TI-202 defect on 4 hour delayed image. 2) Myocardial viability was observed in 38.9% of regions with all motion abnormality on contrast ventriculography. 3) The wall motion score was lower in the segments with persistent TI-201 defect on reinjection image than those with transient defect(p<0.05). 4) In 42.9% of the regions with wall motion abnormality on contrast ventrculography before coronary artery bypass graft, normal TI-201 image was observed after coronary artery bypass graft. CONCLUSION: Thallium-201 reinjection image can be used to identify viable myocardium in segments that demonstrate a persistent thallium defect on conventional delayed images patients with chronic coronary artery disease and left venticular dysfuction.