Utility of Chemical Shift Imaging and Diffusion-weighted Images/Apparent Diffusion Coefficient Maps as a Tool for Evaluation of Solid Renal Tumors.

OBJECTIVES: To study the utility of chemical shift imaging (CSI) and diffusion-weighted images (DWI)/apparent diffusion coefficient (ADC) maps for the evaluation of solid renal tumors. METHODS: Magnetic resonance imaging (MRI) has an equivalent application as computerized tomography (CT) in the characterization of renal masses. It offers a radiation-free imaging technique and has a better soft tissue contrast than CT. Also, MRI is favored in patients with chronic kidney disease. MRI is useful when findings on CT are equivocal. The role of DWI in characterizing solid renal lesions as malignant is encouraging, and DWI can be particularly useful when gadolinium is contraindicated. CSI is useful in differentiating angiomyolipoma (AML) from clear cell (cc) renal cell carcinoma (RCC). We did a cross-sectional study on 24 patients with solid renal masses. MRI of the upper abdomen (from the dome of the diaphragm to the iliac crest) will be done on an MRI machine in our department (1.5T, ACHIEVA, Phillips medical system) using the torso coil. RESULT: There was no significant association seen in terms of ADC values and histological subtypes (χ2 = 11.222, p = 0.082). In our study, 50% (one out of two) of AML showed a signal drop, whereas 40% of cases (6 out of 15) of ccRCC and 66% (two out of three) of papillary RCC showed a signal drop. CONCLUSION: In this article, we concluded CSI, although a useful tool to look for microscopic fat, can't be used as a reliable marker to rule in cc-carcinoma as both AML and papillary cell carcinoma have microscopic fat. Further, no histological classification can be done on the basis of DWI/ADC images.

Management of Nontraumatic Spontaneous Renal Hemorrhage (Wünderlich Syndrome) through Robotic-Assisted Laparoscopic Nephrectomy: A Case Series.

BACKGROUND Wünderlich syndrome (WS) is a rare diagnosis of nontraumatic spontaneous renal hemorrhage into the subcapsular, perirenal, or pararenal spaces. Prompt and effective intervention is necessary for an accurate pathological diagnosis and preservation of life. In the current literature, open surgery is the primary option when conservative treatment fails, but there can be serious trauma and corresponding consequences. Herein, we present 3 cases of Wünderlich syndrome managed by robot-assisted laparoscopic nephrectomy via a retroperitoneal approach. CASE REPORT Patient 1 was a 44-year-old woman with right flank pain for 6 h. Patient 2 was a 53-year-old woman with a history of diabetes who had pain in her right flank pain and nausea for 1 day. Patient 3 was a 45-year-old man with left flank pain for 1 day. All cases of WS were confirmed by CT. All 3 patients were treated with retroperitoneal robot-assisted nephrectomy after conservative treatment failed. Pathological examination confirmed that patient 1 had angiomyolipoma, and patients 2 and 3 had renal clear cell carcinoma. At the 9-month follow-up, renal function was good and no evidence of recurrence or metastasis has been detected. CONCLUSIONS These cases have highlighted the importance of the clinical history and imaging findings in the diagnosis of Wünderlich syndrome, and show that rapid management can be achieved using robot-assisted laparoscopic nephrectomy. However, it is crucial to have a skilled surgical team and adequate preoperative preparation.

Spontaneous rupture of renal angiomyolipoma in pregnancy mimicking preterm labour.

Ruptured renal angiomyolipoma in pregnancy is uncommon. Pregnant women may present with nonspecific symptoms such as flank or abdominal pain, contraction pain and haematuria. A thorough assessment is needed to reach the correct diagnosis. Management varies between conservative measures, radiological intervention or surgery depending on the patient's haemodynamic status and foetal condition. We present a case of a woman in her 30s, gravida 5 para 3+1 at 28 weeks of gestation, who presented with pain. The pain worsened, and she went into hypovolaemic shock. An exploratory laparotomy and emergency caesarean section were done. Retroperitoneal haematoma was found intraoperatively, but the source of bleeding was difficult to determine. An abdominal CT angiogram subsequently revealed an ongoing bleeding from a ruptured angiomyolipoma. An emergency nephrectomy was performed, and the bleeding was secured.

Renal Collision Tumor: A Case of Small Cell Lung Cancer Metastasis to Renal Angiomyolipoma.

ABSTRACT: A 68-year-old woman presented with chest pain and shortness of breath. Imaging revealed a left hilar mass biopsy-proven as small cell cancer. Concurrently, a macroscopic fat-containing renal lesion consistent with an angiomyolipoma was observed. Systemic therapy achieved stability in the lungs and bones, and palliative radiation targeted the left hilum. However, progressive lung disease and brain metastases necessitated stereotactic radiosurgery for brain lesions. Notably, the renal angiomyolipoma exhibited increased soft tissue component and new focal uptake on FDG PET/CT. Biopsy confirmed metastatic small cell lung cancer within the renal lesion. This case highlights a rare occurrence of a renal collision tumor involving small cell cancer and angiomyolipoma.

Qualitative and quantitative characteristics of CEUS for renal cell carcinoma and angiomyolipoma: a narrative review.

Incidental findings of renal masses are increasing. However, a substantial portion of surgically treated renal masses turn out to be benign on histopathological examination. Thus, there is a clear need for improved pre-surgical assessment to minimize unnecessary invasive procedures. The challenge intensifies when distinguishing between renal cell carcinoma (RCC) and angiomyolipoma (AML) in renal lesions smaller than 4 cm with minimal adipose tissue. In such cases, contrast-enhanced ultrasound (CEUS) has emerged as a valuable diagnostic tool, by utilizing both qualitative and quantitative parameters. Quantitative measures offer objectivity, reliability, and reproducibility compared to qualitative parameters, enabling the characterization of RCC subtypes and differentiation from AML. Qualitative features as enhancement pattern, degree, and peak were less helpful in distinguishing triphasic minimal fat AML (TAML) from epithelioid AML (EAML), with the pseudocapsule sign potentially being the only distinguishing qualitative feature. The pseudocapsule sign was more frequently observed in ccRCCs (38.0%) than in AMLs (15.6%). Moreover, it was detected in 40.0% of EAMLs and 34.5% of ccRCCs but not in TAMLs due to similar growth patterns between EAMLs and low-grade ccRCCs. Quantitative measures such as the time-to-peak (TTP) ratio can further enhance diagnostic accuracy and also TOC ratio should be considered, as it was higher in clear cell RCCs (ccRCCs) and in EAMLs compared to TAMLs, indicating behavior similar to ccRCCs. However, CEUS remains an operator-dependent exam.

The association between computed tomography attenuation value of renal angiomyolipoma associated with tuberous sclerosis complex and response to everolimus.

BACKGROUND: The response to everolimus in patients with renal angiomyolipoma associated with tuberous sclerosis complex (TSC-RAML) varies among individuals. This study aims to identify potential factors associated with the response to everolimus. METHOD: We retrospectively examined data encompassing age, gender, tumor size, computed tomography attenuation value (CT value), CT enhancement, and tumor reduction rate in patients with TSC-RAML undergoing everolimus in two previously registered clinical trials. RESULT: A total of 33 participants (29.33 ± 6.63 years old, 20 females) were included. The correlation analysis conducted separately for tumors located in the left and right kidneys revealed significant negative correlations (P < 0.05) between tumor reduction rate and age, as well as tumor size. While significant positive correlations (P < 0.05) were observed between tumor reduction rate and unenhanced CT value as well as CT enhancement. Nonetheless, based on multiple linear regression analysis, unenhanced CT value emerged as the sole-independent predictor of tumor reduction rate among age, gender, tumor size, unenhanced CT value and CT enhancement for both left (coefficient = 0.00319, P < 0.0001) and right kidneys (coefficient = 0.00315, P = 0.0104). Notable reductions were observed in unenhanced CT value (- 3.81 vs - 24.70HU, P < 0.0001) and CT enhancement (48.16 vs 33.56HU, P < 0.0001) following a 3-month administration of everolimus. The decline in both unenhanced CT value and tumor size predominantly occurred within the initial 3 months, subsequently maintaining a relatively stable level throughout the treatment. CONCLUSION: The unenhanced CT value of TSC-RAML showed an independent correlation with the response to everolimus, suggesting its potential as a predictor of everolimus efficacy in patients with TSC-RAML.

Renal angiomyolipoma: from imaging to intervention.

A high volume of cross-sectional imaging has created a window of opportunity for radiologists to identify renal angiomyolipomas (AMLs). The purpose of this review is to help the reader recognise the spectrum of renal AML appearances using different imaging methods and to gain an understanding of the classic and atypical features for appropriate lesion characterisation. Risk factors for AML growth and rupture will be highlighted. An overview of the imaging features of acute AML rupture will be provided, principally relating to computed tomography (CT) assessment. A series of cases will be presented, including a case of peripartum renal AML rupture during Caesarean section leading to diagnostic dilemma. The indications for intervention and available treatment options will be considered: medical therapy, surgery, and interventional radiology (IR) techniques including their pros and cons. Emergency interventional radiology management with selective transarterial embolisation will be presented and analysed in relation to technique, angiographic appearances (pre and post embolisation) and associated complications.

Natural history of renal angiomyolipoma in a high-volume center: our experience during more than 15 years of follow up.

OBJECTIVES: To describe the natural history of AML, the clinical results and the need for treatment during long-term follow-up of renal AML. METHODS: Retrospective study of patients diagnosed with AML by computed tomography or nuclear magnetic resonance between 2001 and 2019, with at least two follow-up images. Clinical and imaging variables, need for intervention, complications and follow-up time were recorded. Statistical analysis was performed using SPSS 22.0. RESULTS: 111 patients and 145 AML were included. The median follow-up was 6.17 years (range 0.7-18.1, IQR 11.8-12.2). The median tumor size at diagnosis was 13 mm (IQR 7.5-30), with 24 (16.4%) being ≥ 4 cm. Most presented as an incidental finding (85.5%); in 3 (2.1%) cases, the presentation was as a spontaneous retroperitoneal hematoma. The main indication for intervention was size ≥ 4 cm in 50%. Eighteen (12%) patients received a first intervention, being urgent in 3. Embolization was performed in 15 cases and partial nephrectomy in 3. The need for reintervention was recorded in five: two underwent partial nephrectomy and two total nephrectomy; one patient required a new urgent embolization. Of the non-operated patients, 43% decreased in size or did not change, while 57% increased, with the median annual growth being 0.13 mm (IQR - 0.11 to 0.73). There were no differences in the median growth in tumors measuring ≥ 4 cm (0.16 mm) at diagnosis vs. < 4 cm (0.13 mm) (p = 0.9). CONCLUSIONS: The findings of this study suggest that AML typically demonstrate a slow-progressing clinical course during long-term follow-up. Moreover, our observations, which cast doubt on tumor size as a reliable predictor of adverse clinical outcomes, advocate for a less intensive monitoring strategy in both monitoring frequency and choice of imaging modality.

Role of Contrast-Enhanced Ultrasound With the Enhancement Pattern and Qualitative Analysis for Differentiating Hypovascular Solid Renal Lesions.

OBJECTIVE: The aim of the work described here was to explore the clinical value of contrast-enhanced ultrasound (CEUS) with the enhancement pattern and qualitative analysis in distinguishing different types of hypovascular solid renal lesions. METHODS: A total of 140 patients with 140 renal tumors (all diagnosed by pathology), which manifested hypo-enhancement on CEUS, were included in this study. We compared conventional ultrasound (US) and CEUS features in five common hypovascular renal tumors, including renal angiomyolipoma (RAML), clear cell renal cell carcinoma (ccRCC), renal pelvic urothelial carcinoma (RPUC), papillary renal cell carcinoma (pRCC) and chromophobe renal cell carcinoma (chRCC). The diagnostic value of conventional US and qualitative parameters of CEUS for differentiating hypovascular solid renal lesions were evaluated. RESULTS: The mean age of patients with a benign renal lesion was younger than that of patients with a malignant renal lesion (p < 0.05). Echogenicity and qualitative parameters such as wash-out, perfusion defects and perilesional rim-like enhancement (PRE) in the two groups differed significantly (all p values <0.05). Benign renal lesions exhibited mainly slow wash-out, whereas malignant renal lesions exhibited predominantly fast wash-out on CEUS (p < 0.05). There were significant differences in echogenicity, such as between RAML and ccRCC, between RAML and RPUC and between RAML and pRCC (all p values <0.05). The rates of appearance of perfusion defect in ccRCC (48%, 13/27) and pRCC (53%, 10/19) were significantly higher than the rate in RAML (14%, 6/43) (p < 0.05). The rates of appearance of PRE in ccRCC (15%, 4/27), pRCC (26%, 5/19) and chRCC (24%,4/17) were significantly higher than the rate in RAML (9%, 4/43) (p < 0.05). CONCLUSION: CEUS with the enhancement pattern and qualitative analysis may be helpful in distinguishing malignant from benign hypovascular renal lesions.

A case report of anterior mediastinal angiomyolipoma that invaded the left thoracic cavity.

RATIONALE: Angiomyolipoma is a mesenchymal tumor composed of blood vessels, smooth muscle, and mature adipose tissue. It is most commonly found in the kidney, and is rare outside the kidney, especially in the mediastinum. Only about 12 cases have been reported worldwide so far. PATIENT CONCERNS: We report a young female patient who had been found with a left thoracic mass for 19 years. In the past 19 years, the patient had no chest pain, dyspnea and other symptoms, but this time she visited the doctor because of cough, and there were no other clinical signs. DIAGNOSES: The patient underwent computed tomography plain scan and enhanced scan after admission with imaging manifestations of a mixed density mass in the left chest cavity, calcification and fat density in the inside, and tortuous blood vessels after enhancement. Combined with imaging, the diagnosis was teratoma, not excluding hamartoma. INTERVENTIONS: The patient underwent a central open thoracic giant mass resection. OUTCOMES: The postoperative pathology confirmed that it was angiomyolipoma originating from anterior mediastinum invasion of the left chest cavity, and no clear recurrence was seen after 1 year of postoperative follow-up. LESSONS: Angiomyolipomas in the mediastinum are rare, especially those that invade the thorax. This article describes the clinical, imaging and pathological features of the patient in detail, which improves the understanding of the disease of clinical and imaging doctors, and provides a basis for the differential diagnosis of mediastinal lesions.

Differentiation between renal epithelioid angiomyolipoma and clear cell renal cell carcinoma using clear cell likelihood score.

PURPOSE: Clear cell likelihood score (ccLS) may be a reliable diagnostic method for distinguishing renal epithelioid angiomyolipoma (EAML) and clear cell renal cell carcinoma (ccRCC). In this study, we aim to explore the value of ccLS in differentiating EAML from ccRCC. METHODS: We performed a retrospective analysis in which 27 EAML patients and 60 ccRCC patients underwent preoperative magnetic resonance imaging (MRI) at our institution. Two radiologists trained in the ccLS algorithm scored independently and the consistency of their interpretation was evaluated. The difference of the ccLS score was compared between EAML and ccRCC in the whole study cohort and two subgroups [small renal masses (SRM; ≤ 4 cm) and large renal masses (LRM; > 4 cm)]. RESULTS: In total, 87 patients (59 men, 28 women; mean age, 55±11 years) with 90 renal masses (EAML: ccRCC = 1: 2) were identified. The interobserver agreement of two radiologists for the ccLS system to differentiate EAML from ccRCC was good (k = 0.71). The ccLS score in the EAML group and the ccRCC group ranged from 1 to 5 (73.3% in scores 1-2) and 2 to 5 (76.7% in scores 4-5), respectively, with statistically significant differences (P < 0.001). With the threshold value of 2, ccLS can distinguish EAML from ccRCC with the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 87.8%, 95.0%, 73.3%, 87.7%, and 88.0%, respectively. The AUC (area under the curve) was 0.913. And the distribution of the ccLS score between the two diseases was not affected by tumor size (P = 0.780). CONCLUSION: The ccLS can distinguish EAML from ccRCC with high accuracy and efficiency.

Development and external validation of the multichannel deep learning model based on unenhanced CT for differentiating fat-poor angiomyolipoma from renal cell carcinoma: a two-center retrospective study.

PURPOSE: There are undetectable levels of fat in fat-poor angiomyolipoma. Thus, it is often misdiagnosed as renal cell carcinoma. We aimed to develop and evaluate a multichannel deep learning model for differentiating fat-poor angiomyolipoma (fp-AML) from renal cell carcinoma (RCC). METHODS: This two-center retrospective study included 320 patients from the First Affiliated Hospital of Sun Yat-Sen University (FAHSYSU) and 132 patients from the Sun Yat-Sen University Cancer Center (SYSUCC). Data from patients at FAHSYSU were divided into a development dataset (n = 267) and a hold-out dataset (n = 53). The development dataset was used to obtain the optimal combination of CT modality and input channel. The hold-out dataset and SYSUCC dataset were used for independent internal and external validation, respectively. RESULTS: In the development phase, models trained on unenhanced CT images performed significantly better than those trained on enhanced CT images based on the fivefold cross-validation. The best patient-level performance, with an average area under the receiver operating characteristic curve (AUC) of 0.951 ± 0.026 (mean ± SD), was achieved using the "unenhanced CT and 7-channel" model, which was finally selected as the optimal model. In the independent internal and external validation, AUCs of 0.966 (95% CI 0.919-1.000) and 0.898 (95% CI 0.824-0.972), respectively, were obtained using the optimal model. In addition, the performance of this model was better on large tumors (≥ 40 mm) in both internal and external validation. CONCLUSION: The promising results suggest that our multichannel deep learning classifier based on unenhanced whole-tumor CT images is a highly useful tool for differentiating fp-AML from RCC.

Renal angiomyolipoma: Beyond size criteria for predicting rupture.

INTRODUCTION: Renal angiomyolipomas (AMLs) are vascular tumours that while histologically benign, carry a risk of rupture and potentially life-threatening haemorrhage. Selective arterial embolisation (SAE) has been demonstrated as effective treatment; however, given most tumours are asymptomatic, the challenge facing the radiologist is selection of which AML should undergo treatment. This study considers presence and size of intratumoural aneurysm, to advance the readers treatment decision-making beyond historical size criteria. METHODS: Retrospective cohort analysis of all SAE-treated AML at a quaternary-level institution in the last 10 years was completed independently by two radiologists. Computerised tomography (CT) and angiographic imaging were reviewed to evaluate tumour size, presence of intratumoural aneurysm and aneurysm size. Univariant and multivariant statistical analyses were used to identify predictors of spontaneous rupture and haemorrhage. RESULTS: Twenty-seven renal AML underwent SAE. Five tumours had presented with haemorrhage. Twenty-two were asymptomatic or without CT/angiographic detectable haemorrhage. There was no statistically significant size difference between ruptured (mean 7.8 cm, range 6.1-12.0 cm) and unruptured AML (7.5 cm, 3.3-21.7 cm) in the study population. Eighty percent of ruptured AML and 27% of unruptured AML contained at least one intratumoural aneurysm (P-value < 0.05). Mean aneurysm size in ruptured AMLs was 5.4 mm, versus 4.6 mm among unruptured AML (P-value > 0.05). CONCLUSION: The presence of intratumoural aneurysm is a useful predictor for AMLs that are at risk of spontaneous rupture and haemorrhage. Intratumoural aneurysm should therefore be considered when selecting patients to undergo SAE.

CT radiomics for differentiating fat poor angiomyolipoma from clear cell renal cell carcinoma: Systematic review and meta-analysis.

PURPOSE: Differentiation of fat-poor angiomyolipoma (fp-AMLs) from renal cell carcinoma (RCC) is often not possible from just visual interpretation of conventional cross-sectional imaging, typically requiring biopsy or surgery for diagnostic confirmation. However, radiomics has the potential to characterize renal masses without the need for invasive procedures. Here, we conducted a systematic review on the accuracy of CT radiomics in distinguishing fp-AMLs from RCCs. METHODS: We conducted a search using PubMed/MEDLINE, Google Scholar, Cochrane Library, Embase, and Web of Science for studies published from January 2011-2022 that utilized CT radiomics to discriminate between fp-AMLs and RCCs. A random-effects model was applied for the meta-analysis according to the heterogeneity level. Furthermore, subgroup analyses (group 1: RCCs vs. fp-AML, and group 2: ccRCC vs. fp-AML), and quality assessment were also conducted to explore the possible effect of interstudy differences. To evaluate CT radiomics performance, the pooled sensitivity, specificity, and diagnostic odds ratio (DOR) were assessed. This study is registered with PROSPERO (CRD42022311034). RESULTS: Our literature search identified 10 studies with 1456 lesions in 1437 patients. Pooled sensitivity was 0.779 [95% CI: 0.562-0.907] and 0.817 [95% CI: 0.663-0.910] for groups 1 and 2, respectively. Pooled specificity was 0.933 [95% CI: 0.814-0.978]and 0.926 [95% CI: 0.854-0.964] for groups 1 and 2, respectively. Also, our findings showed higher sensitivity and specificity of 0.858 [95% CI: 0.742-0.927] and 0.886 [95% CI: 0.819-0.930] for detecting ccRCC from fp-AML in the unenhanced phase of CT scan as compared to the corticomedullary and nephrogenic phases of CT scan. CONCLUSION: This study suggested that radiomic features derived from CT has high sensitivity and specificity in differentiating RCCs vs. fp-AML, particularly in detecting ccRCCs vs. fp-AML. Also, an unenhanced CT scan showed the highest specificity and sensitivity as compared to contrast CT scan phases. Differentiating between fp-AML and RCC often is not possible without biopsy or surgery; radiomics has the potential to obviate these invasive procedures due to its high diagnostic accuracy.