Contrast-enhanced US in Renal Transplant Complications: Overview and Imaging Features.

Renal transplant is the first-line treatment of end-stage renal disease. The increasing number of transplants performed every year has led to a larger population of transplant patients. Complications may arise during the perioperative and postoperative periods, and imaging plays a key role in this scenario. Contrast-enhanced US (CEUS) is a safe tool that adds additional value to US. Contrast agents are usually administered intravenously, but urinary tract anatomy and complications such as stenosis or leak can be studied using intracavitary administration of contrast agents. Assessment of the graft and iliac vessels with CEUS is particularly helpful in identifying vascular and parenchymal complications, such as arterial or venous thrombosis and stenosis, acute tubular injury, or cortical necrosis, which can lead to graft loss. Furthermore, infectious and malignant graft involvement can be accurately studied with CEUS, which can help in detection of renal abscesses and in the differentiation between benign and malignant disease. CEUS is also useful in interventional procedures, helping to guide percutaneous aspiration of collections with better delimitation of the graft boundaries and to guide renal graft biopsies by avoiding avascular areas. Potential postprocedural vascular complications, such as pseudoaneurysm, arteriovenous fistula, or active bleeding, are identified with CEUS. In addition, newer quantification tools such as CEUS perfusion are promising, but further studies are needed to approve its use for clinical purposes. ©RSNA, 2024 Supplemental material is available for this article.

Abnormal grey matter structural changes in patients with end-stage kidney disease and mild cognitive impairment: correlations with clinical features.

End-stage kidney disease and mild cognitive impairment (ESKD-MCI) affect the quality of life and long-term treatment outcomes of patients affected by these diseases. Clarifying the morphological changes from brain injuries in ESKD-MCI and their relationship with clinical features is helpful for the early identification and intervention of MCI before it progresses to irreversible dementia. This study gathered data from 23 patients with ESKD-MCI, 24 patients with ESKD and non-cognitive impairment (NCI), and 27 health controls (HCs). Structural magnetic resonance studies, cognitive assessments, and general clinical data were collected from all participants. Voxel-based morphometry analysis was performed to compare grey matter (GM) volume differences between the groups. The patients' GM maps and clinical features were subjected to univariate regression to check for possible correlations. Patients with ESKD-MCI displayed significantly more impairments in multiple cognitive domains, including global cognition, visuospatial and executive function, and memory, compared to patients with ESKD-NCI. Using a more liberal threshold (P < 0.001, uncorrected), we found that compared to patients with ESKD-NCI, patients with ESKD-MCI exhibited clusters of regions with lower GM volumes, including the right hippocampus (HIP), parahippocampal gyrus (PHG), Rolandic operculum, and supramarginal gyrus. The volumes of the right HIP and PHG were negatively correlated with serum calcium levels. ESKD-MCI was associated with a subtle volume reduction of GM in several brain areas known to be involved in memory, language, and auditory information processing. We speculate that these slight morphometric impairments may be associated with disturbed calcium metabolism.

Nuclear medicine imaging findings in end-stage renal disease and renal transplant complications.

The aim of this review is to discuss end-stage renal disease (ESRD) and renal transplant complications and present the nuclear medicine imaging findings. The conditions discussed are renal osteodystrophy, metastatic calcification, and renal transplant complications, such as vascular occlusion and acute tubular necrosis. A total of eight nuclear medicine imaging scintigraphy primarily of bone and renal scintigraphy were selected and the imaging features of the complications are discussed. This article highlights the role of nuclear medicine imaging in diagnosis, quantitative and qualitative assessment of renal function, and monitoring of complications associated with ESRD and renal transplant.

The stiffness of transplanted kidneys changes with time after renal transplantation.

BACKGROUND: Kidney transplantation is one of the most effective ways to treat end-stage kidney disease. However, 5000 renal transplant recipients start or restart dialysis because of chronic allograft nephropathy (CAN) every year in the United States. Detecting changes in the stiffness of transplanted kidneys can help diagnose transplanted kidney disease. PURPOSE: To explore changes in the stiffness of transplanted kidneys after renal transplantation using shear wave elastography (SWE). MATERIAL AND METHODS: This study conducted consecutive follow-up observations on 10 patients after kidney transplantation. SWE examination was performed in the first week, second week, first month, second month, third month, fourth month, fifth month, and sixth month after surgery. This study also analyzed the graft stiffness of 86 patients with stable renal function recovery one month after surgery. RESULTS: The results show that there is a change in the stiffness of the transplanted kidney over time after renal transplantation. It decreases rapidly within one month after renal transplantation and tends to be stable after one month. The mean renal cortical and pyramidal stiffness of patients with stable renal function were 28.48 ± 4.27 kPa and 21.97 ± 3.90 kPa, respectively. CONCLUSION: Consecutive stiffness measurement of transplanted kidneys is an effective method for monitoring the function of transplanted kidneys. According to the change in transplanted kidney stiffness, we can designate a more scientific review plan to determine the functional status of the transplanted kidney.

Radiation dose from medical imaging in end stage renal disease patients: a Nationwide Italian Survey.

BACKGROUND AND OBJECTIVES: End stage renal disease (ESRD) patients are exposed to the risk of ionizing radiation during repeated imaging studies. The variability in diagnostic imaging policies and the accompanying radiation doses across various renal units is still unknown. We studied this variability at the centre level and quantified the associated radiation doses at the patient level. METHODS: Fourteen Italian nephrology departments enrolled 739 patients on haemodialysis and 486 kidney transplant patients. The details of the radiological procedures performed over one year were recorded. The effective doses and organ doses of radiation were estimated for each patient using standardized methods to convert exposure parameters into effective and organ doses RESULTS: Computed tomography (CT) was the major contributor (> 77%) to ionizing radiation exposure. Among the haemodialysis and kidney transplant patients, 15% and 6% were in the high (≥ 20 mSv per year) radiation dose groups, respectively. In haemodialysis patients, the most exposed organs were the liver (16 mSv), the kidney (15 mSv) and the stomach (14 mSv), while the uterus (6.2 mSv), the lung (5.7 mSv) and the liver (5.5 mSv) were the most exposed in kidney transplant patients. The average cumulative effective dose (CED) of ionizing radiation among centres in this study was highly variable both in haemodialysis (from 6.4 to 18.8 mSv per patient-year; p = 0.018) and even more so in kidney transplant (from 0.6 to 13.7 mSv per patient-year; p = 0.002) patients. CONCLUSIONS: Radiation exposure attributable to medical imaging is high in distinct subgroups of haemodialysis and transplant patients. Furthermore, there is high inter-centre variability in radiation exposure, suggesting that nephrology units have substantially different clinical policies for the application of diagnostic imaging studies.

Abnormal degree centrality in end-stage renal disease (ESRD) patients with cognitive impairment: a resting-state functional MRI study.

To investigate functional connectivity (FC) changes in end-stage renal disease (ESRD) patients with and without cognitive impairment (CI) by using resting-state functional magnetic resonance imaging (rs-fMRI). Twenty-three ESRD patients with CI, 22 ESRD patients with non-CI (NCI) and 23 matched healthy controls (HC) were included. Rs-fMRI scans were performed in all subjects. Full-range, long-range, and short-range FC defined voxel-wise based degree centrality (DC) and seed based FC were computed and contrasted among the groups. Compared with HC, the DC value of short functional connectivity (SFC), in ESRD patients have increased on the left supramarginal gyrus, while it reduced on the left insula and right postcentral gyrus in CI and decreased on the right precentral gyrus in NCI. Compared with NCI, the DC value of LFC in CI increased on the left fusiform gyrus, while the DC value of short functional connectivity (SFC) increased on the left middle orbital gyrus. In the seed-based FC analyses, the CI showed significantly decreased FC between the left insula and bilateral middle temporal gyrus, between the left fusiform gyrus and the right hippocampus, and between the left postcentral gyrus and the right parahippocampus compared to HC; the CI showed significantly increased FC between the left precuneus and the left fusiform gyrus, between the left postcentral gyrus and the right precuneus compared with NCI. Positive correlations were found between DC values on the right superior frontal gyrus and LDL and BDST, and between MoCA and the DC values on the left insula and the left postcentral gyrus. The altered degree centrality may serve as early biomarkers for CI in ESRD patients.

Myocardial Iron Deficiency Quantification and Effective Cardiac Iron Management Strategy Exploration evaluated by Cardiac T2* Mapping in End-Stage Renal Disease Patients.

PURPOSE: To explore myocardial iron content using Cardiac T2* Mapping in dialysis patients undergoing oral iron therapy or intravenous iron supplements compared to healthy controls. METHODS: Fifty-nine dialysis patients, including 30 peritoneal dialysis (PD) patients who underwent oral iron therapy, 29 hemodialysis (HD) dialysis patients who underwent intravenous iron supplements, and 30 healthy controls were included in the study. Cardiac MRI, including cine, T2 stir, and T2* mapping, was conducted at 3.0T. Quantitive T2* mapping, Cine imaging analysis was performed by two radiologists using cvi42. RESULTS: The global cardiac T2* value was higher in dialysis patients than in healthy controls (27.1 ± 6.29 ms versus 24.6 ± 3.60 ms, p< 0.05). The global cardiac T2* value of PD patients was higher than that of HD patients (28.5 ± 4.30 ms versus 25.x7 ± 3.54 ms, p< 0.05). The anteroseptal cardiac T2* value was higher in PD patients than in healthy controls (32.0 ± 4.49 ms versus 27.8 ± 4.02 ms, p< 0.05). The global T2* value negatively correlated with left ventricular ejection fraction (LVEF), peak radial strain, circumferential strain, and longitudinal strain. CONCLUSION: Our study confirmed that PD patients have myocardial iron deficiency despite undergoing oral iron therapy compared to HD patients who received intravenous iron treatments. And the Cardiac T2* value was found to be an independent risk factor and predictor of LVEF and left ventricular altered mechanics. Intravenous iron supplements may be an effective cardiac iron management strategy in patients with HD-dependent end-stage renal disease.

Síndrome cardiorrenal: aspectos clínicos y ecocardiográficos / Cardiorenal syndrome: Clinical and echocardiographic aspects

Resumen El síndrome cardiorrenal (SCR) es un trastorno en el que intervienen el corazón y los riñones, interactuando y produciendo una disfunción entre ellos en forma aguda o crónica. Existen diferentes fenotipos clínicos bien identificados como «desórdenes del corazón y riñón en los que la disfunción aguda o crónica en un órgano induce la disfunción aguda o crónica del otro¼. La alta incidencia de morbimortalidad cardiovascular presente en los pacientes con enfermedad renal crónica terminal (ERCT), en especial la insuficiencia cardiaca (IC), origina inicialmente una lesión miocárdica que conlleva remodelamiento ventricular, lo cual induce a la activación de mecanismos compensadores, entre los cuales el riñón es pieza fundamental, ya que regula la homeostasis hidroelectrolítica y así el volumen circulante, siendo esto en la etapa dialítica más evidente. Los cambios funcionales y anatómicos cardiovasculares que se producen en estos pacientes son muy prevalentes e incluyen las interacciones hemodinámicas del corazón y los riñones en la insuficiencia cardiaca, y el impacto de la enfermedad aterosclerótica en ambos sistemas de órganos. También describimos estrategias diagnósticas y terapéuticas aplicables al síndrome cardiorrenal, que determinan la importancia de la ecocardiografía como modelo de diagnóstico útil. Finalmente, se analizan las posibilidades de tratamiento y la remisión de las alteraciones funcionales cardiacas con el trasplante renal en los pacientes con ERCT.

Abstract Cardiorenal syndrome (CRS) is a disorder in which the heart and kidneys are involved, interacting and producing a dysfunction between them in an acute or chronic way. There are different clinical phenotypes well identified as "heart and kidney disorders in which acute or chronic dysfunction in one organ induces acute or chronic dysfunction in the other". The high incidence of cardiovascular morbimortality in patients with chronic terminal kidney disease (CKD), especially heart failure (HF), initially causes a myocardial lesion that leads to ventricular remodeling, which induces the activation of compensatory mechanisms, among which the kidney is a fundamental part since it regulates the hydroelectrolytic homeostasis and thus the circulating volume, being this in the dialytic stage more evident. The functional and anatomical changes at cardiovascular level that occur in these patients are very prevalent, and include hemodynamic interactions of the heart and kidneys in heart failure and the impact of atherosclerotic disease in both organ systems. We also describe diagnostic and therapeutic strategies applicable to cardiorenal syndrome, which determine the importance of echocardiography as a useful diagnostic model. Finally, we analyze the possibilities of treatment and remission of cardiac functional alterations with renal transplantation in patients with T-CKD.

Gut dysbiosis-influence on amygdala-based functional activity in patients with end stage renal disease: a preliminary study.

Patients with end-stage renal disease (ESRD) are notably accompanied by cognitive disorder and anxiety or depressive symptom. We aimed to explore the linkages of the amygdala-based MR parameters, cognitive and mood performance, systematic inflammation and gut microbiota in ESRD. This prospective study enrolled 28 ESRD patients (13 males and 15 females, mean age of 43.9 ± 13.8 years) and 19 age- and sex-matched healthy control (HC) (12 males and 7 females, mean age of 44.1 ± 10.0 years). All subjects underwent cognitive assessment, inflammatory factor and stool microbiota analysis, and brain MRI analysis [amygdala-based functional connectivity and voxel-based morphometry (VBM)]. ERSD was separated by different microbiota strains. All factors were compared between ESRD and HC, as well as between ESRD subgroups. Pearson correlation analysis and causal mediation analysis were conducted to further investigate the relationship among the factors derived from the gut microbiota, brain and systemic inflammation. ESRD displayed gut dysbiosis and increased systemic inflammation when compared to HC (all P < 0.05). Meanwhile, ESRD showed smaller VBM in amygdala, decreased functional connectivity in left amygdala - right inferior parietal lobe [P < 0.05, Gaussian Random Field (GRF) corrected] and worse cognitive or mood performance. Moreover, ESRD-B (Prevutella mainly), when compared to ESRD-A (Bacteroides mainly), displayed increased interleukin-6, self-rating anxiety scale and functional connectivity in left amygdala - bilateral anterior cingulate cortex / medial superior frontal cortex (P < 0.05, GRF corrected). Furthermore, the correlation network of ESRD showed that both gut dysbiosis and amygdala-based alteration were correlated with cognitive performance and systemic inflammation. Causal mediation analysis validated that the disrupted distribution of Roseburia indirectly regulated the amygdala-based functional connectivity through tumor necrosis factor-alpha. The gut dysbiosis induced by ESRD was closely related to pro-inflammatory cytokines, amygdala-based phenotype, and mood performance. The lower abundance in Roseburia indirectly modulated amygdala-based functional connectivity pattern by tumor necrosis factor-alpha, which might provide a new way in diagnosis and treatment in patients of ESRD with depressive/anxious mood.

Ultrasound-guided percutaneous peritoneal dialysis catheter insertion using multifunctional bladder paracentesis trocar: A modified percutaneous PD catheter placement technique.

BACKGROUND: To evaluate the efficacy and safety of ultrasound-guided percutaneous peritoneal dialysis catheter insertion using multifunctional bladder paracentesis trocar. METHODS: A retrospective review of 103 ESRD patients receiving percutaneous PD catheter insertion using a multifunctional bladder paracentesis trocar under ultrasound guidance at a single center between May 2016 and May 2018. Mechanical complications and catheter survival were evaluated over a 12-month follow-up. RESULT: Catheterization using this technique required only 10-30 minutes from the beginning of local anesthesia to the end of skin suture at the puncture site (mean 18 ± 7 minutes) and an incision length of 2-4 cm. Moreover, only four of 103 cases required catheter removal due to poor drainage within one month after surgery, with a success rate of 96.19%. Among failures, omentum wrapping was cause in two cases, catheter displacement in one case, and protein clot blockage in one case, while there were no instances of organ injury, severe hemorrhage, peritubular leakage, hernia, peritonitis, or exit infection within one month of PD catheter insertion. Catheter survival at 1 year was 92.2%. CONCLUSION: Percutaneous PD catheter insertion using a multifunctional bladder paracentesis trocar and ultrasound guidance is a feasible technique for ESRD patients.

Successful use of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) on a pancreatic lesion in a peritoneal dialysis patient without interrupting treatment.

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA), a well-established minimally invasive gastrointestinal procedure, has been used to diagnose and stage cancers of the pancreas. We describe the successful use of EUS-FNA in a peritoneal dialysis (PD) patient to evaluate a pancreatic cyst. The patient continued on PD immediately after the procedure without using hemodialysis. The patient did not experience any complication such as infection, bleeding, or peritoneal fluid leakage.

Comparison of shoulder Magnetic Resonance Imaging findings between patients with stage 4 chronic kidney disease and hemodialysis patients with healthy controls.

BACKGROUND: Shoulder involvement is frequently observed in chronic renal disease (CRD) and hemodialysis patients. OBJECTIVE: Our aim is to compare shoulder Magnetic Resonance Imaging (MRI) findings of stage 4 CRD patients naive to dialysis, hemodialysis patients and healthy controls. METHODS: Twenty hemodialysis patients with shoulder pain (Group 1), 30 hemodialysis patients without shoulder pain (Group 2), 20 patients with stage 4 CRD (Group 3) and 30 healthy controls (Group 4) were enrolled. Urea, creatinine and ß2 microglobulin were measured. Thickness, homogeneity and integrity of rotator cuff and presence of effusion were examined by MRI. RESULTS: Supraspinatus tendon was thicker in Group 1 compared to other groups, whereas infraspinatus tendon was thicker in Group 1 compared to Groups 2 and 4. Although all tendons thickness was higher in Group 3 than Group 4, there was no significant difference. Most effusion areas were present in Group 1, followed by Groups 2 and 3. There was a significant correlation between glomerular filtration rate and thickness of supraspinatus, infraspinatus tendons and between ß2 microglobulin and thickness of infraspinatus, subscapularis tendons and total number of areas with effusion. CONCLUSIONS: Increased shoulder tendon thickness and effusion were detected in symptomatic dialysis patients, while greater effusion areas were detected in asymptomatic dialysis patients and in stage 4 CRD patients who do not require dialysis compared to healthy controls.

Renal sinus fat and renal hemodynamics: a cross-sectional analysis.

OBJECTIVES: Increased renal sinus fat (RSF) is associated with hypertension and chronic kidney disease, but underlying mechanisms are incompletely understood. We evaluated relations between RSF and gold-standard measures of renal hemodynamics in type 2 diabetes (T2D) patients. METHODS: Fifty-one T2D patients [age 63 ± 7 years; BMI 31 (28-34) kg/m2; GFR 83 ± 16 mL/min/1.73 m2] underwent MRI-scanning to quantify RSF volume, and subcutaneous and visceral adipose tissue compartments (SAT and VAT, respectively). GFR and effective renal plasma flow (ERPF) were determined by inulin and PAH clearances, respectively. Effective renal vascular resistance (ERVR) was calculated. RESULTS: RSF correlated negatively with GFR (r = - 0.38; p = 0.006) and ERPF (r = - 0.38; p = 0.006) and positively with mean arterial pressure (MAP) (r = 0.29; p = 0.039) and ERVR (r = 0.45, p = 0.001), which persisted after adjustment for VAT, MAP, sex, and BMI. After correction for age, ERVR remained significantly related to RSF. CONCLUSIONS: In T2D patients, higher RSF volume was negatively associated to GFR. In addition, RSF volume was positively associated with increased renal vascular resistance, which may mediate hypertension and CKD development. Further research is needed to investigate how RSF may alter the (afferent) vascular resistance of the renal vasculature.

Cardiac MRI measurements of pericardial adipose tissue volumes in patients on in-centre nocturnal hemodialysis.

BACKGROUND: Conversion from conventional hemodialysis (CHD) to in-centre nocturnal hemodialysis (INHD) is associated with left ventricular (LV) mass regression, but the underlying mechanisms are not fully understood. Using cardiac MRI (CMR), we examined the effects of INHD on epicardial adipose tissue (EAT) and paracardial adipose tissue (PAT), and the relationships between EAT, PAT and LV remodeling, biomarkers of nutrition, myocardial injury, fibrosis and volume. METHODS: We conducted a prospective multicenter cohort study of 37 patients transitioned from CHD to INHD and 30 patients on CHD (control). Biochemical markers and CMR were performed at baseline and 52 weeks. CMR images were analyzed by independent readers, blinded to order and treatment group. RESULTS: Among 64 participants with complete CMR studies at baseline (mean age 54; 43% women), there were no significant differences in EAT index (60.6 ± 4.3 mL/m2 vs 64.2 ± 5.1 mL/m2, p = 0.99) or PAT index (60.0 ± 5.4 mL/m2 vs 53.2 ± 5.9 mL/m2, p = 0.42) between INHD and CHD groups. Over 52 weeks, EAT index and PAT index did not change significantly in INHD and CHD groups (p = 0.21 and 0.14, respectively), and the changes in EAT index and PAT index did not differ significantly between INHD and CHD groups (p = 0.30 and 0.16, respectively). Overall, changes in EAT index inversely correlated with changes in LV end-systolic volume index (LVESVI) but not LV end-diastolic volume index (LVEDVI), LV mass index (LVMI), and LV ejection fraction (LVEF). Changes in PAT index inversely correlated with changes in LVESVI, LVMI and positively correlated with changes in LVEF. There were no correlations between changes in EAT index or PAT index with changes in albumin, LDL, triglycerides, troponin-I, FGF-23, or NT-proBNP levels over 52 weeks (all p > 0.30). CONCLUSIONS: INHD was not associated with any changes in EAT index and PAT index over 12 months. Changes in EAT index were not significantly associated with changes in markers of LV remodeling, nutrition, myocardial injury, fibrosis, volume status. In contrast, changes in PAT index, which paradoxically is expected to exert less paracrine effect on the myocardium, were correlated with changes in LVESVI, LVMI and LVEF. Larger and longer-term studies may clarify the role of PAT in cardiac remodeling with intensified hemodialysis. CLINICALTRIALS. GOV IDENTIFIER: NCT00718848.

MRI for diagnosis of post-renal transplant complications: current state-of-the-art and future perspectives.

Kidney transplantation has developed into a widespread procedure to treat end stage renal failure, with transplantation results improving over the years. Postoperative complications have decreased over the past decades, but are still an important cause of morbidity and mortality. Early accurate diagnosis and treatment is the key to prevent renal allograft impairment or even graft loss. Ideally, a diagnostic tool should be able to detect post-transplant renal dysfunction, differentiate between the different causes and monitor renal function during and after therapeutic interventions. Non-invasive imaging modalities for diagnostic purposes show promising results. Magnetic resonance imaging (MRI) techniques have a number of advantages, such as the lack of ionizing radiation and the possibility to obtain relevant tissue information without contrast, reducing the risk of contrast-induced nephrotoxicity. However, most techniques still lack the specificity to distinguish different types of parenchymal diseases. Despite some promising outcomes, MRI is still barely used in the post-transplantation diagnostic process. The aim of this review is to survey the current literature on the relevance and clinical applicability of diagnostic MRI modalities for the detection of various types of complications after kidney transplantation.