Multiphasic Helical CT Criteria for Differentiation of Recurrent Neoplasm and Desmoplastic Reaction after Laparoscopic Resection of Renal Mass Lesions

Local recurrence of renal cell carcinoma after partial nephrectomy: applicability of the apparent diffusion coefficient of MRI as an imaging marker - a multicentre study

Purpose

The goal of the study was an assessment of the diagnostic performance of diffusion-weighted images (DWI) and apparent diffusion coefficient (ADC) of magnetic resonance imaging (MRI) in distinguishing local recurrence (LR) of renal cell carcinoma (RCC) from benign conditions after partial nephrectomy.

Material and methods

Thirty-nine patients after partial nephrectomy for solid RCC were enrolled in the study. Patients were followed up using MRI, which included DWI sequence (b = 800 s/mm²). All patients with MRI features of LR were included in the main group (n = 14) and patients without such features – into the group of comparison (n = 25). Apparent diffusion coefficient (ADC) values of suspicious lesions were recorded. In all patients with signs of locally recurrent RCC, surgical treatment was performed followed by pathologic analysis.

Results

The mean ADC values of recurrent RCC demonstrated significantly higher numbers compared to benign fibrous tissues and were 1.64 ± 0.15 × 10^-3 mm²/s vs. 1.02 ± 0.26 × 10^-3 mm²/s (p < 0.001). The mean ADC values of RCCs’ LR and benign post-op changes in renal scar substantially differed from mean ADC values of healthy kidneys’ parenchyma; the latter was 2.58 ± 0.05 × 10^-3 mm²/s (p < 0.001). In ROC analysis, the use of ADC with a threshold value of 1.28 × 10^-3 mm²/s allowed us to differentiate local recurrence of RCC from benign postoperative changes with 100% sensitivity, 80% specificity, and accuracy: AUC = 0.980 (p < 0.001).

Conclusions

The apparent diffusion coefficient of DWI of MRI can be used as a potential imaging marker for the diagnosis of local recurrence of RCC.

Mimics and Pitfalls in Renal Imaging

There are several potential pitfalls that radiologists face when interpreting images of the kidneys. Some result from image acquisition and can arise from the imaging equipment or imaging technique, whereas others are patient related. Another category of pitfalls relates to image interpretation. Some difficulties stem from methods to detect enhancement after contrast administration, whereas others are benign entities that can mimic a renal tumor. Finally, interpretation and diagnosis of fat-containing renal masses may be tricky due to the complexities discerning the pattern of fat within a mass and how that translates to an accurate diagnosis.

Biomedical imaging in the safety evaluation of new drugs

Toxicology accounts for approximately one-third of attrition in new drug development and is a major concern in the pharmaceutical industry. This paper reviews the role of biomedical imaging in the safety evaluation of new candidate drugs. Ex vivo high-resolution three-dimensional imaging of specimens can provide a quick overview of the specimens. Volumetric measurements of tissue structures and lesions can be made with higher precision and reproducibility than histology approaches. As opposed to histology, in vivo animal imaging permits longitudinal studies of the same animals over an extended period of time, with individual animals serving as their own control. Therefore, the number of animals required for a study can be significantly reduced and the intra-subject variability is minimized. Repeated in vivo imaging allows monitoring of the occurrence and progression, or regression, of various structural and functional abnormalities. Compared with other biological assays, imaging can provide anatomically specific information about tissue abnormality. Imaging offers the opportunity to carry forward the same methodology in animal experiments into human studies and has an important role in clinical trials when other safety biomarkers for early toxicities are not available.

Contemporary imaging modalities for the surveillance of patients with renal cell carcinoma

In recent years, there have been multiple advances in imaging technologies that have improved the surveillance for recurrence of neoplasms. Multidetector row CT and dynamic contrast enhanced MRI now provide excellent anatomic detail and are beginning to show functional detail as the rapid capture of images following contrast administration improves. Positron emission tomography is emerging as a useful tool in evaluating patients with suspected metastatic disease to the abdomen and bone, particularly when combined with CT. The role of ultrasound in the surveillance of renal cell carcinoma is yet unclear, but its role may be expanding with use of newly developed contrast drugs. Herein we review the relevance of these modalities to the follow-up of patients with renal cell carcinoma.

Imaging findings after minimally invasive nephron-sparing renal therapies

With the trend towards minimally invasive and nephron-sparing surgery for renal masses, laparoscopic partial nephrectomy and energy ablative techniques have become common approaches to treat low-stage tumours. Complications following such techniques are occasional, especially for ablation techniques. This review illustrates the imaging of these complications and of tumour recurrence, with the conclusion that imaging plays an important role in their diagnosis, and in the infrequent situation that intervention is needed, helps to plan subsequent management.

Retroperitoneal Fibrosis, Today: An Updating of Knowledges on this Subjet

Retroperitoneal fibrosis (RPF) is characterized, at first, by a replacement of the normal retroperitoneal tissue by an active granulomatosis inflammation (cellular phase), and at a later stage by a fibrous scar tissue (established fibrotic phase). The aetiology of secondary RPFs includes several drugs (notably methysergide, ergotamine, pergolide, hydralazine), both chronic atherosclerotic aortitis-periaortitis and inflammatory aortic aneurisms, autoimmune diseases such as different forms of systemic vasculitis and collagen diseases, histiocytosis such as Erdheim-Chester syndrome, desmoplastic reactions to retroperitoneal malignancy carcinoid syndrome, retroperitoneal accidentally and surgically occurred traumas, abdominal radiation therapy.

On the contrary, the causes of idiopathic RPF remain uncertain; its pathogenesis is associated to immuno-mediated mechanisms. The inflammatory process can involve retroperitoneal vessels, ureters, peri- and pararenal spaces, mesenteric small intestine, duodenum, psoas muscles, and can spread to mediastinal space. Diagnosis and characterization of the polyphase inflammatory evolution require integrated approaches including laboratory tests, morpho-functional imaging and, sometimes, histopathologic assessment. In the early stages, the management of RPF ranges from the removal of identifiable etiologic agents to the interfering with the inflammatory immuno-mediated process by means of several drugs. Unfortunately, many effective immunosuppressive drugs induce adverse reactions unrelated to their specific immunosuppressive action; this is the reason why the biopharmacology research today is struggling towards the identification of molecular targets having their expression restricted to immune cells and/or cytokines. Moreover, the progression of atheromatous aortitis to RPF could be prevented by statins which are able to interfere with the inflammatory pathway as well as to induce the well-known reduction in the levels of atherogenic lipoproteins. In the late established fibrotic stage, either open surgery or endourologic, laparoscopic procedures are performed; nevertheless neoadiuvant and adiuvant corticosteroid-immunosuppressive treatments are mandatory in order to avoid any relapse of the disease.