1. AbstractPurpose: This studyaims to explorethe clinical utilityof radionuclide tracer technology in the diagnosis and localization of thoracoabdominal fistulas. Methods:99mTc-DTPAwasthoroughlymixedwiththeperitoneal dialysis fluid before continuously beingintroducedinto the peritoneal cavity through a peritoneal dialysis tube. Dynamic acquisition in the supine-anteroposterior position and SPECT/CT fusion imaging were performed simultaneously on the same ma-chine. Results:Radioactivityconcentrationintherightthoraciccav- ity gradually increased after dynamic collection and was abnormallydistributedin4min. SPECT/CTtomographicfusion depict- ed a right chest co-abdominal fistula, and the spot was accurately located. Conclusion: Using radioisotope tracing technology of 99mTc-DTPA SPECT and CT tomographyon the same machine, a simple, accurate qualitative, and localized diagnosis of pleural effusioncan bemadecausedbyabdominalleakagethatprovidesa visualized objective basis forsubsequent treatment.
2. Medical Records he peritoneum as a semipermeable membrane, the peritoneal dialysate is continuously replaced to eliminate metabolites and tox- in substances and correct water and electrolyte imbalances. The thoracoabdominal fistula is one of the rare but serious complica- tions associated with peritoneal dialysis. Edward and Unger first reported the thoracoabdominal fistula in 1967 [1]. Radionuclide imagingisa medical imagingtechnique that usesradionuclides or theirlabeled compoundstodeterminethefunction andstructureof organsandtissues.
2. IntroductionTrichosporon asahii is a yeast-like opportunistic fungus that causes agranulocytosis or immunodeficiency, exposure to broad-spectrum antibiotics or steroid hormones, implantation of invasive medical devices, and inappropriate use of antifungal drugs. The most common cause of severe invasive Trichosporon spp infections, accounting for approximately 68%-90%. Up to 80% of the patients suffer catheter-associated fungemia, and the mortality rate is 40%-90% [1-6]. T. asahii can form complex three-dimensional grid-like biofilms on the surface of implanted devices, and the ERG11 gene can reduce azole affinity, which is the cause of its high drug resistance and mortality. Containing the underlying diseases and sources of infection, resection of implanted devices, recovery of granulocytes, and voriconazole treatment can improve prognosis [1-3,6-8]. The patient in this article was diagnosed with acute myeloid leukemia. At the time of onset, the patient was in the process of allogeneic stem cell transplantation for hematopoiesis, and the immune system has not yet been rebuilt. He has almost all high-risk factors for the occurrence of T. asahii infection. The clinical manifestations include fungemia, and multiple organs such as skin, lung, liver, spleen, kidneys, and eyes are involved, similar to those reported in the literature [1-8]. This is the patient with the most organs involved at the same time in the reports related to T. asahii infection, suggesting that we should conduct multi-organ screening for systemic disseminated infection in a timely manner when fungemia occurs. The early papersreported that strains were found in the corridor air, laminar flow bed, equipment clean room, washbasin, and patient pollutants of hematology wards with disseminated infection of T. asahii, suggesting the possibility of cross-infection [9-11]. However, a recent study in Japan found that the colonization rate of T. asahii in the feces of healthy subjects was 60%, and the genotype was almost the same as that of the clinically reported isolates, the authors also speculate that early colonization of the gastrointestinal tract by the strain may be associated with the late-stage development of trichosporidiosis [6]. Kurakado et al. isolated 4 strains in 5 patients with COVID-19 combined with T. asahii infection, which reduced the possibility of infection transmission [1]. Most of the predominant molecular genotypes of T. asahii are type 1, followed by types 3 and 5, but there is no significant relationship between strain genotypes and virulence, antifungal drug susceptibility, and clinical prognosis [2,12-15]. In the 2021 edition of the Global Guidelines for the Diagnosis and Management of Rare Yeast Infections, voriconazole or posaconazole are recommended as firstline drugs because of their highest antibacterial activity, followed by fluconazole which shows moderate sensitivity. Amphotericin B exhibits variable minimum inhibitory concentrations (MICs) and is recommended for second-line therapy. The guideline does not recommend it due to the natural resistance of T. asahii to echinocandins [1-5,13-16]. Since serum concentrations of antimicrobials have not been mentioned in previously reported cases, it remains unclear whether they play an important role in the development of breakthrough infections. In this study, the disseminated T. asahii infection was not contained even when the blood concentration of posaconazole reached the standard preventive dose (≥0.7ug/ml), while the treatment with voriconazole was effective. This implies that the latter has a higher affinity to fungal 14-α - demethylases, while inhibiting the demethylation of 24-methylenedihydrolanosterol in yeast and filamentous fungi. it can inhibit the demethylation of 24-methylenedihydrolanosterol in yeast and filamentous fungi, and thus achieve the purpose of treatment. It is speculated that patients with immunocompromised patients are more dependent on the bactericidal activity of fungal drugs. Considering that voriconazole is not metabolized by the kidneys, while amphotericin B has the Pharmacokinetic characteristics of hypermetabolism in the kidneys, we tried the combined drug when the patient had a urinary tract infection. The effect was remarkable. In addition, the onset of fungal endophthalmitis is insidious, the treatment cycle is long and difficult, and it is likely to leave permanent organ functional damage. During the anti-infection process, the fundus should be regularly monitored. Finally, ethanol disinfection can effectively inhibit the biofilm formation of T. asahii [8], and the combined use of berberine and amphotericin B has a synergistic destruction effect on planktonic cells and biofilms of T. asahii [17] and achieved good results in the care of patients with skin ulcers. In conclusion, disseminated T. Asahii infection is a rare yeast infection that involves multiple organs. Early detection, early diagnosis and treatment, and combined medication can improve the prognosis.
3. CaseDataA 57-year-old woman receiving maintenance peritoneal dialysis for more than a year was admitted to the hospitalwith abdominal distension and pain for a week. In the beginning, peritoneal dialysis consisted of 1.5% 2 L peritoneal dialysis solutions three times daily. Eventually, due to edema of both lower extremities, the peritoneal dialysis program was changed toa 1.5% 2 Lperitoneal dialysis solution, two times a day, and a 2.5% 2 L peritoneal dialysis solution, two times a day,to strengthen the dehydration. A reduction in lower extremity edema was observed. Abdominal ultrasonography revealed that the edema suddenly became preva- lent(400mL/day).Whiletheamountexceeded about400mLafter adjustingthe plan, abdominal distentionanddiscomfort accompa- nied by nausea and vomiting started one week ago after consum- ing the liquid. There was right hydrothorax and right pulmonary tissue compression on post-admission thoracic CT. The right thoracicpuncturewasthenperformedtodrainaclearyellowliquid.A routine biochemical examination of the pleural effusion revealed leakageandelevatedglucoselevelsinthehydrothorax, whichwas inconsistent with serum glucose levels. There was the possibility that a thoracoabdominal fistula could develop. Basedonsurgi- cal consultation, the location of ruptured pleural fistula could not be determined, nor could it be effectively repaired. The nuclear medicine department performeda radionuclidelocalization examination to confirm diagnosis and location of the thoracoabdominal leakage. A concrete inspection method involved thoroughly mixing10mCi99mTc-DTPAwithperitonealdialysissolutionand delivering it as a continuous infusion through a peritoneal dialysis tube. The patient was lying on SPECT examination table and the dynamicacquisition of local anteroposterior position was performed (specific parameterswere 1 s/framefor 1 min;then 1min/ frame for 15 min). The scanning device is an Infinia Hawkeye 4 SPECT/CTmanufacturedbyGE ofAmerica.Thescanningdevice is equipped with a lowenergyandhigh-resolutioncollimator, ma trix 64×64, peak 140 Kev, and a window width of 20%. Xeleris, Functional Imaging Workstation software, was used for post-processing analysis.
4. ResultsAfterinjection,thedynamiccollection showedthattheperisplenic and abdominal cavities gradually developed and thickened with the diffusion ofimagingagent. At 4min, twostrips ofradioactive exudation were visible on the right diaphragm. Abnormal accumulation of radioactivity and continuous enrichment in the right thoracic cavity were observed, as shown in Figure 1. SPECT/CT simultaneous tomography fusionimaging was utilized to locate the fistula. No abnormal radioactive accumulation in the left thoracic cavity was observed, as depicted in Figure 2. Conservative treatment has been recommended following a surgical consultationuntilthechest,andabdominalleaksheal spontaneously. After startinghemodialysis, abdominal pain,nausea, vomiting, and other symptoms gradually subsided. Follow-up abdominal and chest CT showed that thehydrothorax steadilydecreased overtime. cavity. Conservative treatment has been recommended following a surgical consultation until the chest, and abdominal leaks heal spontaneously. After starting hemodialysis, abdominal pain, nausea, vomiting, and other symptoms gradually subsided. Follow-up abdominal and chest CT showed that the hydrothorax steadilydecreased over time.
5. DiscussionAccording to Liyanage et al. [2] global use of renal replacement therapy(dialysis and kidneytransplantation) is predicted toreach 5.439 million (3.899-7.64 million) by 2030. Dialysis is the most common form of renal replacement therapy, except for a very small number of patients who can receive kidney transplantation [3]. Peritoneal dialysis is superior to hemodialysis in reducing adverse reactions, improving nutritional status and quality of life [4,5].Peritonealdialysishasamoresignificantprotectiveeffecton residual renal function without adversely impacting hemodynamics 4. Peritoneal dialysis is the best alternative to hemodialysis, including cost and ease of use [6]. Peritoneal dialysis, congenital diaphragm dysplasia, lymphatic drainage disorder, and chest-abdominal pressure difference are also known causes of chest-abdominal fistulas. Hydrothorax is a rare complication in peritoneal dialysis (PD) [7]. The diagnosis of thoracoabdominal fistula on peritoneal dialysis is generally based on biochemistry of pleural effusion, identification of the composition, intraperitoneal injection of methylene blue, plain chest radiographs, and CT or MRI abdominal angiography [8]. Contrast media must be injected into theabdominal cavitythrough a catheter toperform theaboveimagingtechniques. Inadditiontobeingtime-consumingandrequiring professional training to complete, infusion of contrast media can cause complications such as chemical peritonitis [9]. Safe, noninvasive, simple, and accurateevaluation of pleural effusion caused bythoracoabdominalleakage,andevenprojectionofitstrajectory, provides an objective basis for guiding subsequent treatment and prognosis. Radionuclide tracer technologyconstitutes the essence of functional imaging in nuclear medicine, with high safety and sensitivity and low chemical and radiation doses. This technology corresponds more closely to the physiological state of the human body.Developing nuclearmedicinetechnology hasresulted in many advances in molecular imaging and functional imaging [10]. In vitro radionuclide imaging provides a non-invasive in vitro method for observing the distributionof radioactive nuclidesinthe chest and abdomen inreal-time to guide thoracoabdomi- nal fistula diagnosis and localization. In conjunction with radio- nuclide imaging, the thoracoabdominal fistula can be diagnosed and the fistula can be located by comparing the leakage site and surrounding tissue with radionuclide imaging. Functional imag- ing in nuclear medicine is a typical application of radionuclide tracing using functional imaging techniques. The results of this studydifferfrompreviousreportsofdirectinjectionofradioactive tracers into the body. In this study, the unabsorbed 99mTc-DTPA was thoroughly mixed with the dialysis solution and then continuously injected through peritoneal dialysis tubes, allowing not onlyto improve detection rates but also tomore closelymatch the pathophysiologycharacteristicsofdialysis patients.Thisstudyhas limitations owing to a substandard leak point display. There may be misalignment, as Tomosynthesis acquisition time is long, and SPECT and CT acquisition are asynchronous. Due to the aging of themodel used,thespatialresolutionofSPECTandCTistoolow. Therefore, there aretwoleakage pointsinthedynamic acquisition ofthefrontandrearplanes.After dynamicacquisition,theleakage point is not well visualized in SPECT/CT simultaneous tomographyfusion imaging.
6. ConclusionsInthisstudy,99mTc-DTPAwasinjectedintotheabdominalcavity andperitonealdialysis solution whileaSPECTdynamicscan was performed simultaneously. With CT tomography fusion imaging technology, the qualitative diagnosis ofthoracoabdominal fistulas can be ascertained, but it also offers the advantages of non-invasiveness, safety, accuracy, andvisualitythatmeritfurtherap
7. Funding:This research was supported by “Anhui Provincial Natural Science Foundation [2008085QH406], Anhui Medical University Joint Project of Nuclear Medicine and Radiation Medicine [2021lcxk035]”.
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