Imaging Patients with Kidney Failure.

The approach to imaging a patient with kidney failure continues to evolve. Overstatement of the risk of iodinated contrast material-induced (ie, contrast-induced) acute kidney injury and new guidelines for administration of gadolinium-based contrast media affect screening and the choice of contrast material. Treatment of kidney failure requires dialysis or a kidney transplant. Pretransplant imaging includes assessment for the feasibility of performing a transplant and evaluation for underlying malignancy and peripheral vascular disease. Patients with kidney failure are at high risk for renal cell carcinoma. Subtypes that occur exclusively or more commonly in patients with kidney failure, such as acquired cystic kidney disease, renal cell carcinoma, and clear cell papillary renal cell carcinoma, have specific clinical-pathologic characteristics, with indolent behavior. Performing US for dialysis planning increases the success of placement of an arteriovenous fistula, while postoperative US evaluation is essential in assessment of access dysfunction. Systemic manifestations in patients with kidney failure are multifactorial and may relate to the underlying cause of renal failure or may be secondary to treatment effects. Disturbances in mineral and bone metabolism and soft-tissue and vascular calcifications are seen in patients with chronic kidney disease and mineral bone disorder. Neurologic and cardiothoracic complications are also common. The authors provide a comprehensive overview of imaging considerations for patients with kidney failure, including the appropriate use of CT, MRI, and US with their respective contrast agents; the use of imaging in transplant workup and dialysis assessment; and the common renal and extrarenal manifestations of kidney failure. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Exclusión renal por endometriosis profunda ureteral: a propósito de un caso / Renal exclusion due to deep infiltrating ureteral endometriosis: a case report

INTRODUCCIÓN: La endometriosis ureteral es una afección rara que afecta al 0.01-1,7% de las mujeres con endometriosis. Hasta un 30% cursa de forma asintomática y un 11,5-14,7% pueden evolucionar con falla renal. La falta de diagnóstico de la enfermedad puede terminar en una uropatía obstructiva y falla renal irreversible. Se presenta el caso de una paciente con afectación grave de la función renal secundaria a endometriosis profunda con compromiso ureteral. CASO CLÍNICO: Mujer de 35 años con endometriosis que consultó por exacerbación de los síntomas. En su estudio destaca, en la resonancia magnética, el hallazgo de endometriosis pélvica profunda y compromiso endometriósico intrínseco del uréter distal derecho, provocando una acentuada hidroureteronefrosis. El cintigrama renal demuestra acentuado compromiso de la función renal derecha, con una función relativa del 7%. Se realizaron nefrectomía total derecha y resección de enfermedad pélvica profunda laparoscópica, sin incidentes. CONCLUSIONES: La endometriosis ureteral representa un desafío diagnóstico y terapéutico. El manejo multidisciplinario entre radiólogos, ginecólogos y urólogos, mediante el diseño de una estrategia quirúrgica individualizada, es imprescindible para definir el tratamiento óptimo de estas pacientes.

INTRODUCTION: Ureteral endometriosis is a rare entity that affects 0.01-1,7% of women with endometriosis. Up to 30% of the patients are asymptomatic and 11.5-14.7% will develop renal failure. Misdiagnosis can lead to obstructive uropathy and permanent renal failure. We present the case of a patient with severe compromise of renal function secondary to deep infiltrating endometriosis with ureteral involvement. CASE REPORT: A 35-year-old woman with endometriosis presented with exacerbation of symptoms. Magnetic resonance showed deep pelvic endometriosis and intrinsic endometriotic involvement of the right distal ureter, causing a marked hydroureteronephrosis. Renal scintigram showed a severe compromise of the right renal function, with a relative function of 7%. Through laparoscopy a total right nephrectomy and resection of deep infiltrating endometriosis was performed. The patient had a satisfactory recovery in the postoperative period. CONCLUSIONS: Ureteral endometriosis presents a diagnostic and therapeutical challenge. Joint multidisciplinary management between radiologists, gynecologists and urologists through the design of an individualized surgical strategy is essential to define the optimal treatment for these patients.

Disparities between IgG4-related kidney disease and extrarenal IgG4-related disease in a case-control study based on 450 patients.

We aimed to compare the demographic, clinical and laboratory characteristics between IgG4-related kidney disease (IgG4-RKD+) and extrarenal IgG4-related disease (IgG4-RKD-) in a large Chinese cohort, as well as describing the radiological and pathological features of IgG4-RKD+. We retrospectively analyzed the medical records of 470 IgG4-related disease (IgG4-RD) patients at Peking University People's Hospital from January 2004 to January 2020. The demographic, clinical, laboratory, radiological and pathological characteristics between IgG4-RKD+ and IgG4-RKD- were compared. Twenty IgG4-RD patients who had definite etiology of renal impairment including diabetes, hypertension and etc. were excluded. Among the remained 450 IgG4-RD patients, 53 were diagnosed with IgG4-RKD+ . IgG4-RKD+ patients had older age at onset and at diagnosis. Male to female ratio of IgG4-RKD+ patients is significantly higher. In the IgG4-RKD+ group, the most commonly involved organs were salivary gland, lymph nodes and pancreas. It was found that renal function was impaired in approximately 40% of IgG4-RKD+ patients. The most common imaging finding is multiple, often bilateral, hypodense lesions. Male sex, more than three organs involved, and low serum C3 level were risk factors for IgG4-RKD+ in IgG4-RD patients. These findings indicate potential differences in pathogenesis of these two phenotypes.

Prognosis of patients in prolonged coma after severe carbon monoxide poisoning.

BACKGROUND: Late recovery in patients following prolonged coma from carbon monoxide poisoning have been reported, but the probability is unclear. The purpose of this research was to assess the prognosis of patients in prolonged coma after severe carbon monoxide poisoning and related clinical and imaging features. METHODS: There were 13 patients who had been in a state of coma for >7 days after acute carbon monoxide poisoning in the retrospective observational study, and demographic data, clinical data, laboratory data, complications, and image data were collected. Outcome was assessed by means of the Glasgow outcome scale after 1 year. The relationship between complications and imaging manifestations and prognosis was also analyzed. RESULTS: One year after severe carbon monoxide poisoning, two patients (15.4%) had died (GOS 1), nine (69.2%) were in a persistent vegetative state (GOS 2), one (7.7%) was moderately disabled (GOS 4), and one (7.7%) achieved a good recovery (GOS 5) with minimal disability. CONCLUSIONS: Most patients with prolonged coma after severe carbon monoxide poisoning had a poor prognosis, although the younger patients had a better prognosis. Respiratory failure, hypotension and renal failure during the course of the disease were associated with a poor prognosis. The prognosis of patients with injuries in two sites in early CT was poor. Multiple lesions (≥3) and extensive white matter damage (Fazekas grade (PVH or DWMH) = 3) on MRI of chronic phase were also associated with a poor prognosis.

Prognostic impact of 18F-FDG PET/CT in patients with multiple myeloma presenting with renal impairment.

Renal insufficiency (RI) is a frequent manifestation of multiple myeloma (MM) at time of diagnosis but there is no reliable prognostic factor for patients with MM presenting with RI. This study investigated the prognostic impact of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in patients with MM with RI at diagnosis. The records of 209 patients with MM between June 2011 and November 2018 were retrospectively analyzed. PET/CT positivity was defined as the presence of more than three focal lesions or the presence of extramedullary disease. Of 209 patients, 90 (43.1%) had RI and showed similar survival outcomes to patients who had normal renal function. In total, 113 patients (54.0%) were PET/CT-positive, and 46.6% of patients with RI were PET/CT-positive at baseline. In patients with RI, those who were PET/CT-positive showed significantly inferior survival outcomes to those who were PET/CT-negative [progression-free survival (PFS), 12.7 vs. 34.0 months, P < 0.001; overall survival (OS), 42.2 months vs. not reached, P = 0.001]. On multivariate analysis, PET/CT positivity was significantly associated with PFS and OS in patients with RI. In conclusion, PET/CT is a reliable imaging technique for predicting survival outcomes in patients with MM with RI.

Co-Existence of Sarcoidosis and Sjögren's Syndrome with Hypercalcemia and Renal Involvement: A Case Report and Literature Review.

BACKGROUND: Sarcoidosis and Sjögren's syndrome (SS) are chronic multi-system inflammatory diseases of unknown origin that most commonly attack the salivary glands. Both of the diseases have vague and non-specific symptoms, causing difficulties for the clinicians to distinguish between the two diseases. Main diagnostic criteria of SS exclude sarcoidosis. However, a co-existence of both diseases should be noted. Here, a case of co-existing sarcoidosis and Sjögren's syndrome is reported, complicated with severe hypercalcemia and renal failure, in addition to a literature review. CASE PRESENTATION: A 71-year-old man visited our hospital complaining of daily progressive oral dryness, thirst, and blurred vision with a feeling of dry eyes for a one-year duration. His physical examination showed enlargement of both sides of cervical and supraclavicular lymph nodes. Lung auscultation showed decreased breath sounds with bibasilar inspiratory crackles. However, initial laboratory results revealed severe hypercalcemia with moderate hypercalciuria and renal failure. The final diagnosis was co-existing SS and sarcoidosis according to clinical, radiological, and laboratory data. The patient received oral prednisone therapy for 18 months. After a follow-up of years, the serum calcium concentration, renal function, and chest CT scan remained normal after prednisone treatment stopped for more than 18 months. CONCLUSION: In the literature, calcium metabolic disorder and renal involvement have not been reported among patients with Sarcoidosis and Sjögren's syndrome, suggesting that calcium metabolic disorder may be underestimated. Serum and urine calcium concentration should be measured in addition to routine laboratory tests.

Bone Marrow Sarcoidosis with Pancytopenia and Renal Failure Presenting as Fever of Unknown Origin: The Pivotal Role of 18F-FDG PET/CT in Lesion Detection.

We describe a case of fever of unknown origin (FUO), renal failure, and pancytopenia. Initially, lymph proliferative disorder was suspected; therefore, bone marrow biopsy and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) were performed. Bronchoscopy and lung biopsy were performed because of abnormal FDG uptake in both lung fields. Imaging data and laboratory and histological results confirmed sarcoidosis with bone marrow invasion. The patient was discharged after favorable response to corticosteroid therapy. Sarcoidosis may present as FUO without typical specific presentations in the skin or lungs. Combined 18F-FDP PET/CT helped identify the biopsy site and confirmed the sarcoidosis diagnosis.

Magnetic resonance imaging-guided laser-induced thermal therapy for functional hemispherotomy in a child with refractory epilepsy and multiple medical comorbidities.

Magnetic resonance imaging-guided laser-induced thermal therapy (MRgLITT) is a minimally invasive surgical approach increasingly employed for precise targeted ablation of epileptogenic brain foci. Recent reports have described corpus callosotomy using MRgLITT, though its application in more extensive functional disconnections has not been documented. Here, the authors detail its use in achieving a palliative hemispherotomy in a 5-year-old with medically refractory hemiclonic seizures following a hemispheric infarction, highlighting a novel use of this surgical technique. In this particular case, open craniotomy was deemed high risk given the multiple medical comorbidities including congenital cardiac disease and end-stage renal failure. MRgLITT was considered an alternative approach with a lower risk for periprocedural hemodynamic perturbations. The patient tolerated the procedure well, attaining an Engel class IB outcome at 16 months' follow-up. This suggests that MRgLITT may be an alternative approach to an open hemispherectomy, particularly in cases in which multiple comorbidities pose significant risks and preclude an open procedure.

Case Report: Paralytic Ileus: A Potential Extrapulmonary Manifestation of Severe COVID-19.

The COVID-19 pandemic has recently spread worldwide, presenting primarily in the form of pneumonia or other respiratory disease. In addition, gastrointestinal manifestations have increasingly been reported as one of the extrapulmonary features of the virus. We report two cases of SARS-CoV-2 infection complicated by paralytic ileus. The first patient was a 33-year-old man who was hospitalized with severe COVID-19 pneumonia requiring ventilator support and intensive care. He developed large bowel dilatation and perforation of the mid-transverse colon, and underwent laparotomy and colonic resection. Histopathology of the resected bowel specimen showed acute inflammation, necrosis, and hemorrhage, supporting a role for COVID-19-induced micro-thrombosis leading to perforation. The second patient was a 33-year-old man who had severe COVID-19 pneumonia, renal failure, and acute pancreatitis. His hospital course was complicated with paralytic ileus, and he improved with conservative management. Both cases were observed to have elevated liver transaminases, which is consistent with other studies. Several authors have postulated that the angiotensin-converting enzyme 2 receptors, the host receptors for COVID-19, that are present on enterocytes in both the small and large bowel might mediate viral entry and resultant inflammation. This is a potential mechanism of paralytic ileus in cases of severe COVID-19 infection. Recognizing paralytic ileus as a possible complication necessitates timely diagnosis and management.

COVID-19 associated kidney impairment in adult: Qualitative and quantitative analyses with non-enhanced CT on admission.

PURPOSE: To qualitatively and quantitatively assess kidney imapairment in adults with COVID-19 by analysing imaging features on non-enhanced CT (NECT) and possible correlation between renal parenchymal attenuation (RPA) and serum creatinine (SCr) levels on admission. METHODS: This study was approved by the local institutional ethics committee. A total of 82 patients with COVID-19 admitted from 10/1/2020∼15/3/2020 were enrolled. RPA and perinephric fat stranding (PFS) were evaluated on NECT imaging. According to the presence of PFS, the patients were divided into two groups: Group A, 38 patients with PFS, and Group B, 44 patients without PFS. Clinical data, including age, gender, clinical classification, SCr levels, and RPA on NECT were analysed. The RPA and SCr of the two groups with COVID-19 were analysed to determine possible difference and correlation. Eighty subjects with no kidney diseases were randomly selected as control group to determine the RPA of normal kidney performed on the same CT scanner. RESULTS: Mean age, male to female ratio, number of severe and critical cases, and SCr of Group A were higher than those of Group B. Both mean RPA of Group A and Group B were lower than that of control. Mean RPA of Group A was even lower than that of Group B. A significant weak negative linear correlation between RPA on NECT and SCr in COVID-19 was indicated. CONCLUSIONS: Decrease in RPA on NECT was observed in patients with COVID-19 and a weak linear negative correlation with SCr levels was found. The presence of PFS suggested more severe renal impairment in COVID-19. RPA measurements and PFS could be useful in quantitative and qualitative evaluation of COVID-19 associated renal impairment on admission.

Intermodality feature fusion combining unenhanced computed tomography and ferumoxytol-enhanced magnetic resonance angiography for patient-specific vascular mapping in renal impairment.

OBJECTIVE: The purpose of this study was to establish the feasibility of fusing complementary, high-contrast features from unenhanced computed tomography (CT) and ferumoxytol-enhanced magnetic resonance angiography (FE-MRA) for preprocedural vascular mapping in patients with renal impairment. METHODS: In this Institutional Review Board-approved and Health Insurance Portability and Accountability Act-compliant study, 15 consecutive patients underwent both FE-MRA and unenhanced CT scanning, and the complementary high-contrast features from both modalities were fused to form an integrated, multifeature image. Source images from CT and MRA were segmented and registered. To validate the accuracy, precision, and concordance of fused images to source images, unambiguous landmarks, such as wires from implantable medical devices or indwelling catheters, were marked on three-dimensional (3D) models of the respective modalities, followed by rigid co-registration, interactive fusion, and fine adjustment. We then compared the positional offsets using pacing wires or catheters in the source FE-MRA (defined as points of interest [POIs]) and fused images (n = 5 patients, n = 247 points). Points within 3D image space were referenced to the respective modalities: x (right-left), y (anterior-posterior), and z (cranial-caudal). The respective 3D orthogonal reference axes from both image sets were aligned, such that with perfect registration, a given point would have the same (x, y, z) component values in both sets. The 3D offsets (Δx mm, Δy mm, Δz mm) for each of the corresponding POIs represent nonconcordance between the source FE-MRA and fused images. The offsets were compared using concordance correlation coefficients. Interobserver agreement was assessed using intraclass correlation coefficients and Bland-Altman analyses. RESULTS: Thirteen patients (aged 76 ± 12 years; seven female) with aortic valve stenosis and chronic kidney disease and two patients with thoracoabdominal vascular aneurysms and chronic kidney disease underwent FE-MRA for preprocedural vascular assessment, and unenhanced CT examinations were available in all patients. No ferumoxytol-related adverse events occurred. There were 247 matched POIs evaluated on the source FE-MRA and fused images. In patients with implantable medical devices, the mean offsets in spatial position were 0.31 ± 0.51 mm (ρ = 0.99; Cb = 1; 95% confidence interval [CI], 0.99-0.99) for Δx, 0.27 ± 0.69 mm (ρ = 0.99; Cb = 0.99; 95% CI, 0.99-0.99) for Δy, and 0.20 ± 0.59 mm (ρ = 1; Cb = 1; 95% CI, 0.99-1.00) for Δz. Interobserver agreement was excellent (intraclass correlation coefficient, >0.99). The mean difference in offset between readers was 1.5 mm. CONCLUSIONS: Accurate 3D feature fusion is feasible, combining luminal information from FE-MRA with vessel wall information on unenhanced CT. This framework holds promise for combining the complementary strengths of magnetic resonance imaging and CT to generate information-rich, multifeature composite vascular images while avoiding the respective risks and limitations of both modalities.

Using non-contrast-enhanced magnetic resonance venography for the evaluation of May-Thurner syndrome in patients with renal insufficiency: A case report.

RATIONALE: Contrast-enhanced computed tomographic venography (CTV) or magnetic resonance venography (MRV) are usually used to detect May-Thurner syndrome (MTS). However, both are associated with contrast-induced nephrotoxicity. For patients who cannot receive contrast media, non-contrast-enhanced MRV using three-dimensional (3D) turbo spin-echo (TSE) is considered an alternative. We report a case of MTS to describe its clinical utility and advantages. PATIENT CONCERNS: A 49-year-old male experienced isolated left leg swelling and pain for half a month. He had a history of chronic renal insufficiency that made contrast-enhanced imaging studies inadequate. DIAGNOSES: A lower extremity venous Duplex scan showed a thrombus extending from the left distal femoral vein to the popliteal vein with valvular reflux, consistent with infrainguinal deep vein thrombosis (DVT). The suprainguinal DVT was evaluated by non-contrast-enhanced MRV. The results showed sandwich external compression of the left common iliac vein between the right common iliac artery and lumbar vertebrae, consistent with DVT of the left common iliac vein caused by MTS. INTERVENTIONS: The patient received angioplasty with the implantation of a balloon-expandable stent over the left common iliac vein. OUTCOMES: Excellent recanalization of the left iliac vein was noted postoperatively. LESSONS: In the evaluation of suprainguinal venous lesions, non-contrast-enhanced MRV presents the venous structure alone at high resolution without the accompanying arterial structure, which makes it an excellent diagnostic imaging tool for MTS. These findings indicate that non-contrast-enhanced MRV could be useful for detecting systemic venous pathologies in patients with renal insufficiency.

Usefulness of a Pretreatment CT-Based Modified RENAL Nephrometry Score in Predicting Renal Function After Cryotherapy for T1a Renal Mass.

PURPOSE: We investigated the usefulness of the modified RENAL nephrometry (mRN) scoring system for predicting post-cryotherapy renal function in patients with T1a renal mass. PATIENTS AND METHODS: A total of 75 patients with a T1a renal mass were enrolled. The mRN score was determined based on the tumor size, the tumor's exophytic/endophytic properties, the tumor's nearness to the collecting system, and the anterior/posterior location of the kidney. The change in the estimated glomerular filtration rate (ΔeGFR) was calculated as follows: ΔeGFR = 100 × ([pretreatment eGFR - eGFR at 6 months after cryotherapy]/pretreatment eGFR). Based on the ΔeGFR results, we classified the patients into two groups: a preserved renal function group (ΔeGFR < 10%) and an impaired renal function group (ΔeGFR ≥ 10%). We then analyzed the relationships between the mRN score and ΔeGFR and between the mRN score and the chronic kidney disease (CKD) stage. RESULTS: The mean ΔeGFR for all patients was 5.5%. The mRN scores of the preserved renal function group (5.8 ± 0.3) were significantly lower than those of the impaired group (7.4 ± 0.3) (p < 0.001). When the mRN score cutoff value was set at 7 points, the mRN had 67.7% sensitivity, 72.7% specificity, 61.8% positive predictive value (PPV), 76.1% negative predictive value (NPV), and 70.7% accuracy for predicting impaired renal function. For predicting a deterioration of CKD stage, the mRN had 92.9% sensitivity, 67.2% specificity, 39.4% PPV, 97.6% NPV, and 72% accuracy. CONCLUSION: Our newly proposed modified RENAL nephrometry score was suggested to be useful for predicting renal function after renal cryotherapy.

Toxicological Risk Assessments of Iron Oxide Nanocluster- and Gadolinium-Based T1MRI Contrast Agents in Renal Failure Rats.

Gadolinium-based contrast agents (GBCAs) are widely used for T1-weighted magnetic resonance imaging (MRI) in clinic diagnosis. However, a major drawback of GBCAs is that they can increase the toxicological risk of nephrogenic systemic fibrosis (NSF) in patients with advanced renal dysfunction. Hence, safer alternatives to GBCAs are currently in demand, especially for patients with renal diseases. Here we investigated the potential of polyethylene glycol (PEG)-stabilized iron oxide nanoclusters (IONCs) as biocompatible T1MRI contrast agents and systematically evaluated their NSF-related risk in rats with renal failure. We profiled the distribution, excretion, histopathological alterations, and fibrotic gene expressions after administration of IONCs and GBCAs. Our results showed that, compared with GBCAs, IONCs exhibited dramatically improved biosafety and a much lower risk of causing NSF, suggesting the feasibility of substituting GBCAs with IONCs in clinical MRI diagnosis of patients with renal diseases.

Autosomal dominant polycystic kidney disease: new role for ultrasound.

OBJECTIVES: To evaluate the accuracy of US in calculating renal volumes and renal resistive index (RRI) that was obtained using a new method in patients with autosomal dominant polycystic kidney disease (ADPKD). METHODS: In this prospective study, US and MRI were performed in 57 patients with ADPKD (31 female and 26 male; age range, 19-79 years) between August 2017 and May 2018. The volumes determined using US and MRI were compared. The ellipsoid formula was re-evaluated using different multipliers. RRI was obtained 1.5-2 cm distal to the outlet of main renal arteries. The relationship between mean RRI, renal function tests, and kidney volumes and difference between mean RRI of ADPKD patients with and without renal failure were investigated using a two-sided independent samples t test and Pearson correlation test. Interobserver agreements for volume assessments and RRI measurements were determined. RESULTS: By changing the ellipsoid formula, a very good agreement was found (ICC 0.970 for the right kidney and ICC 0.973 for the left kidney). The mean RRI in the right renal artery was 0.61 ± 0.07 and in the left renal artery 0.63 ± 0.06. The mean RRI of ADPKD patients with renal failure was significantly higher than that of patients without renal failure (p = 0.005). There was a significant correlation between mean RRI and renal function tests. CONCLUSION: The accuracy of the US in calculating renal volumes increases by adapting the ellipsoid formula. RRI may be used for the management of ADPKD independently of volumes. KEY POINTS: •The accuracy of ultrasonography for renal volume measurement increases by changing the classical ellipsoid formula. •Renal resistive index measured by color Doppler ultrasonography is helpful for the management of autosomal dominant polycystic kidney disease. •The role of Doppler US in autosomal dominant polycystic kidney disease should increase as a result of our findings.

Easy resolution of severe obstructive kidney injury.

Chronic constipation is a common diagnosis with a high prevalence in the elderly. Constipation affects the quality of life of sick individuals, bringing several clinical complications.