Renal cell carcinoma metastases to the pancreas: value of arterial phase imaging at MDCT

ACR Appropriateness Criteria® Staging of Renal Cell Carcinoma: 2022 Update

Renal cell carcinoma is a complex group of highly heterogenous renal tumors demonstrating variable biological behavior. Pretreatment imaging of renal cell carcinoma involves accurate assessment of the primary tumor, presence of nodal, and distant metastases. CT and MRI are the key imaging modalities used in the staging of renal cell carcinoma. Important imaging features that impact treatment include tumor extension into renal sinus and perinephric fat, involvement of pelvicalyceal system, infiltration into adrenal gland, involvement of renal vein and inferior vena cava, as well as the presence of metastatic adenopathy and distant metastases. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Is a single portal venous phase in contrast-enhanced CT sufficient to detect metastases or recurrence in clear cell renal cell carcinoma? – a single-center retrospective study

Background

This study aims at describing the imaging features of the metastatic presentation of clear cell renal cell carcinoma (ccRCC) in arterial (AP) and portal venous phase (PVP) of contrast-enhanced-computed-tomography (CECT) during clinical follow-up (FU) and to evaluate the necessity of a dual phase approach for metastasis detection.

Methods

We identified a total of 584 patients that were diagnosed with ccRCC between January 2016 and April 2020. Inclusion criteria were histologically proven ccRCC with metastatic spread, proven by histology or interim follow-up of at least 2 years and follow-up CT examination with AP and PVP CECT including thorax/abdomen and pelvis. Exclusion criteria were defined by missing or incomplete CT-scans or lack of sufficient follow-up. CT studies of 43 patients with histologically proven ccRCCs were analyzed in retrospect. AP and PVP images were analyzed by two radiologists for metastases, two additional independent radiologists analyzed PVP images only. A 5-point Likert scale was used to evaluate the likelihood off the presence of metastasis. Imaging patterns of the metastases were analyzed visually.

Results

43 patients (16 female; mean age: 67±10 years) with recurrent ccRCC and metastatic disease were included. Three imaging patterns were observed (solid, heterogeneous or cystic metastases), which rarely exhibited calcifications (2%). All metastases showed hyperenhancement in AP and PVP. Inter-reader agreement was substantial (Fleiss’ κ 0.6–0.8, p<0.001). No significant differences in sensitivity or specificity between readers (AP and PVP images vs. PVP images only) were present (79.4-85.2%, 97.1-99.6%, p ≥ 0.05). The area under the receiver-operating-characteristic (ROC) curve was between 0.901and 0.922 for all four radiologists.

Conclusions

Similar rates for detection, sensitivity and specificity of metastasis and local recurrence in ccRCC were observed irrespective of using a dual-phase protocol with AP and PVP or a single PVP protocol only. Thus, a single-phase examination of PVP can be sufficient for experienced radiologists to detect metastatic disease in the follow-up of ccRCC patients.

Development of CT-Based Imaging Signature for Preoperative Prediction of Invasive Behavior in Pancreatic Solid Pseudopapillary Neoplasm

Purpose

It is challenging for traditional CT signs to predict invasiveness of pancreatic solid pseudopapillary neoplasm (pSPN). We aim to develop and evaluate CT-based radiomics signature to preoperatively predict invasive behavior in pSPN.

Methods

Eighty-five patients who had pathologically confirmed pSPN and preoperative contrasted-enhanced CT imaging in our hospital were retrospectively analyzed (invasive: 24; non-invasive: 61). 1316 radiomics features were separately extracted from delineated 2D or 3D ROIs in arterial and venous phases. 200% (SMOTE) was used to generate balanced dataset (invasive: 72, non-invasive: 96) for each phase, which was for feature selection and modeling. The model was internally validated in the original dataset. Inter-observer consistency analysis, spearman correlation, univariate analysis, LASSO regression and backward stepwise logical regression were mainly applied to screen the features, and 6 logistic regression models were established based on multi-phase features from 2D or 3D segmentations. The ROC analysis and Delong's test were mainly used for model assessment and AUC comparison.

Results

It retained 11, 8, 7 and 7 features to construct 3D-arterial, 3D-venous, 2D-arterial and 2D-venous model. Based on 3D ROIs, the arterial model (AUC: 0.914) performed better than venous (AUC: 0.815) and the arterial-venous combined model was slightly improved (AUC: 0.918). Based on 2D ROIs, the arterial model (AUC: 0.814) performed better than venous (AUC:0.768), while the arterial-venous combined model (AUC:0.893) performed better than any single-phase model. In addition, the 3D arterial model performed better than the best combined 2D model. The Delong's test showed that the significant difference of model AUC existed in arterial models in original dataset (p = 0.019) while not in arterial-venous combined model (p=0.49) as comparing 2D and 3D ROIs.

Conclusion

The arterial radiomics model constructed by 3D-ROI feature is potential to predict the invasiveness of pSPN preoperatively.

Nonepithelial Neoplasms of the Pancreas, Part 2: Malignant Tumors and Tumors of Uncertain Malignant Potential From the Radiologic Pathology Archives

Almost all neoplasms of the pancreas are derived from pancreatic epithelial components, including the most common pancreatic mass, primary pancreatic ductal adenocarcinoma (PDAC). Nonepithelial neoplasms comprise only 1%-2% of all pancreatic neoplasms. Although some may arise directly from intrapancreatic elements, many originate from mesenchymal, hematopoietic, or neural elements in the retroperitoneal peripancreatic space and grow into the pancreas. Once these tumors reach a certain size, it can be challenging to identify their origin. Because these manifest at imaging as intrapancreatic masses, awareness of the existence and characteristic features of these nonepithelial neoplasms is crucial for the practicing radiologist in differentiating these tumors from primary epithelial pancreatic tumors, an important distinction given the vastly different management and prognosis. In part 1 of this article, the authors reviewed benign nonepithelial neoplasms of the pancreas. This article focuses on malignant nonepithelial neoplasms and those of uncertain malignant potential that can be seen in the pancreas. The most common malignant or potentially malignant nonepithelial pancreatic tumors are of mesenchymal origin and include soft-tissue sarcomas, solitary fibrous tumor, and inflammatory myofibroblastic tumor. These tumors commonly manifest as large heterogeneous masses, often containing areas of necrosis and hemorrhage. The clinical features associated with these tumors and the imaging characteristics including enhancement patterns and the presence of fat or calcification help distinguish these tumors from PDAC. Hematopoietic tumors, including lymphoma and extramedullary plasmacytoma, can manifest as isolated pancreatic involvement or secondarily involve the pancreas as widespread disease. Hyperenhancing paragangliomas or hypervascular metastatic disease can mimic primary pancreatic neuroendocrine tumors or vascular anomalies.

Renal Masses: Imaging Evaluation

This article illustrates the imaging characteristics of cystic and solid renal masses, along with a summary of identified imaging criteria that may be of use to differentiate masses that are more likely to be benign from those that are more likely to be malignant. In addition, important features of known or suspected renal cancers that should be identified before treatment are summarized, including staging of renal cancer and RENAL nephrometry. Finally, the imaging appearance of patients following treatment of renal cancer, including after partial or total nephrectomy, thermal ablation, or chemotherapy for metastatic disease, is reviewed.

Metastases to the Pancreas: Computed Tomography Imaging Spectrum and Clinical Features: A Retrospective Study of 18 Patients With 36 Metastases

The aim of this study is to identify the key computed tomography (CT) imaging findings and clinical characteristics of pancreatic metastases for its differential diagnosis. CT images and clinical features of 18 patients with 36 histopathologically proven pancreatic metastases were retrospectively reviewed. The primary malignancy included non-small cell lung cancer (NSCLC) (n = 7), gastrointestinal carcinoma (n = 5), renal cell carcinoma (RCC) (n = 3), osteosarcoma (n = 1), cardiac sarcomas (n = 1), and neuroendocrine ethmoid sinus carcinoma (n = 1). Pancreatic metastases were metachronous in 12 patients (ranging from 4 to 72 months). Tumor markers were elevated for 8 patients, of which 7 patients had NSCLC and gastrointestinal carcinoma, and 1 patient had osteosarcoma. Metastases from NSCLC and gastrointestinal carcinoma frequently presented as small well-circumscribed lesions, with homogeneous or rim enhancement, and or local pancreatic infiltration instead of focal mass, mimicking local pancreatitis. Neuroendocrine ethmoid sinus carcinoma affecting the pancreas also exhibited local pancreatic infiltration. Metastases from RCC and cardiac sarcomas had typical characteristics of hypervascular lesions. Osteosarcoma metastasizing to pancreas had special manifestation, that is, cystic lesion with thick wall and calcification. Although pancreatic metastases have a broad spectrum of CT appearances, lesions from some types of primary tumors exhibited characteristic imaging features, which, in combination with oncological history, will contribute to correct diagnosis.

(18)F-FDG-PET/CT findings in pancreatic metastasis

PURPOSE

This study aimed to evaluate the fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) findings and pattern of FDG uptake in pancreatic metastases.

MATERIALS AND METHODS

A total of 19 consecutive patients (26 lesions) with histologically or clinically confirmed pancreatic metastases who had undergone (18)F-FDG-PET/CT were enrolled in this retrospective study. Among the 19 patients, 14 patients underwent abdominal contrast-enhanced CT (ceCT). The location, size and FDG uptake patterns of the pancreatic lesions were recorded. Metabolic activity by means of maximum standardised uptake value (SUVmax) was measured by drawing regions of interest at the site of pancreatic lesions. Twenty pancreatic cancer patients were included in this study as comparative data analysis. The difference of SUVmax between pancreatic metastases and primary pancreatic cancer were compared using the Mann-Whitney U test. P < 0.05 was considered significant.

RESULTS

Three different patterns of FDG uptake could be distinguished in the pancreatic metastatic lesions, including focal nodule or mass, multiple foci and segmental lesion with high FDG uptake. The average SUVmax in pancreatic metastases was 7.8 ± 6.9 versus 7.4 ± 3.9 in primary pancreatic cancer (P = 0.987 > 0.05). Four intrapancreatic isodense nodules in three patients were undetected on ceCT.

CONCLUSION

The described patterns of FDG uptake findings may be helpful for a better characterisation of pancreatic metastases although semiquantitative analysis using SUVmax could not be used as a criterion for differentiating pancreatic metastases from primary pancreatic cancer. FDG-PET/CT has also an advantage in detecting unsuspected pancreatic metastases which cannot be detected by ceCT imaging. Thus, it is a useful adjunct to the described features on CT.

Pancreatectomy for metastatic disease: a systematic review

AIM

Tumours rarely metastasise to the pancreas. While surgical resection of such metastases is believed to confer a survival benefit, there is limited data to support such management. We present a systematic review of case series of pancreatic metastasectomy and analysis of survival outcomes.

METHODS

A literature search was performed using the PubMed and Cochrane databases and the reference lists of relevant articles, searching for sizeable case series of pancreatic metastasectomy with curative intent. Data extracted included basic demographics, histological primary tumour, presentation, operative management, complications and survival, while the MINORS index was used to assess study quality.

RESULTS

18 studies were found which met our inclusion criteria, involving 399 patients. Renal cell carcinoma (RCC) was the commonest malignancy metastasising to the pancreas, responsible for 62.6% of cases, followed by sarcoma (7.2%) and colorectal carcinoma (6.2%). While survival data was not uniformly reported, the median survival post-metastasectomy was 50.2 months, with a one-year survival of 86.81% and five-year survival of 50.02%. Median survival for RCC was 71.7 months with 70.4% five-year survival. Median survival was similar in patients with synchronous and metachronous pancreatic metastases, but patients with additional extrapancreatic metastases had a significantly shorter survival than patients with isolated pancreatic metastases (26 versus 45 months). Study quality was poor, with a median MINORS score of 10/16.

CONCLUSIONS

Within the limitations of a review of non-randomised case series, it would appear that pancreatic metastasectomy confers a survival benefit in selected patients. Better evidence is required, but may prove difficult to acquire.