Evaluation of Complex Renal Cyst With CEUS/Functional MRI Versus CT
Condition: Cystic Renal Diseases; Kidney Neoplasms
MeSH terms: Kidney Neoplasms; Kidney Diseases, Cystic
Study type: Observational

Summary: 
      The primary concern in complex renal cysts (CRC) with malignant potential is the accurate
      diagnosis and characterization. Patients with CRC have to undergo frequent imaging
      surveillance (every 6-12 Mo), in which the progression suggests a neoplastic process. The
      gold standard for establishing diagnosis and necessity for surgical intervention (i.e.
      partial nephrectomy) is conventional computer tomography (CT) imaging. Its main drawback is
      the radiation dose to the body and intravenous contrast media administration, which has a
      risk of nephrotoxicity.

      Magnetic resonance imaging (MRI) with special functional sequences (fMRI) and
      contrast-enhanced ultrasonography (CEUS) allow measuring tissue blood flow and perfusion
      characteristics without ionizing radiation or nephrotoxic contrast media. To compare the
      diagnostic accuracy, sensitivity and specificity of CEUS/functional MRI versus the gold
      standard CT, 60 patients with CRC will be evaluated using all these 3 modalities. The main
      hypothesis is that fMRI and CEUS have equal accuracy with CT regarding diagnosis and
      classification of CRC lesions.
    

Detailed description: 
      Background

      Renal cysts occur in a variety of diseases but also in normal kidneys (i.e. simple cysts).
      Diagnostic imaging plays a central role in the diagnosis of renal cysts and lesions. Most
      patients are diagnosed after undergoing imaging (computed tomography [CT], magnetic resonance
      imaging [MRI], ultrasound [US]) for an unrelated reason and their increasing incidental
      finding during the last decade parallels the growing use of imaging procedures.

      Simple renal cysts are commonly observed in normal kidneys and are of limited clinical
      relevance. The primary clinical concern is the accurate evaluation of complex renal cysts
      (CRC) that have a malignant potential. Based upon the initial radiographic evaluation,
      further studies may be required, and some complex lesions may require surgical excision for
      exact diagnosis, based on growth during follow up.

      The gold standard for the diagnosis of CRC is conventional CT imaging. Its main drawback is
      the radiation dose to the body and intravenous contrast media administration, which has a
      risk of nephrotoxicity. In order to accurate classify and manage these lesions, the Bosniak
      renal cyst classification system was created. Based upon morphologic and enhancement
      characteristics of the CT scan, cystic renal masses are placed in one of five categories (I,
      II, IIF, III, IV).

      Although not yet validated for reader agreement or generalizability, the Bosniak renal cyst
      classification system has been widely accepted by urologists and radiologists as the best way
      to assess and follow these CRC lesions. While the Bosniak classification is based on CT
      findings, the same approach is applicable as a useful predefined framework for the evaluation
      of CRC with other radiographic modalities i.e. with MRI and conventional or contrast-enhanced
      ultrasound. The ability to differentiate between those that are benign versus malignant
      (surgical versus nonsurgical masses) still represents a major challenge.

      Magnetic resonance imaging (MRI) has gained immense popularity over the last decades as it
      allows generation of very high-resolution images, including 3D reconstructions, without
      ionizing radiation. Functional MRI can be performed with or without injection of contrast,
      thus avoiding the risk of nephrogenic systemic sclerosis in patients with chronic kidney
      disease (CKD). Diffusion weighted imaging (DW-MRI), blood-oxygen-level-dependent (BOLD) MRI
      and arterial spin labeling (ASL) sequences are functional sequences which can be performed
      without injection of contrast.

      The recent development and availability of a contrast-enhanced ultrasonography (CEUS) using
      microbubbles has further improved sensitivity and diagnostic confidence with respect to
      conventional and colour-Doppler US. They allow vascular bed opacification and have opened the
      way to detecting the microcirculation. CEUS was able to detect changes in human renal
      cortical microcirculation. Thus it seems to be a feasible technique to evaluate (i.e.
      perfusion pattern of the cyst wall or perfusion of the septa) CRC using the Bosniak
      classification system.

      Ideally, the method for the evaluation of CRC should be safe, non-invasive, and accurate.
      Abdominal CT scanning delivers significant ionizing radiation, which may be a consideration
      for younger patients (age <35 years), utilizes contrast media with a considerable
      nephrotoxicity and risk of an allergic reaction. No prospective study comparing CT with CEUS
      or functional MRI for the evaluation of CRC has been conducted.

      Objective

      The primary aim of this study is to evaluate the diagnostic accuracy, sensitivity and
      specificity of CEUS/fMRI and compare it with abdominal CT the current gold standard
      diagnostic modality.

      Methods

      Prospective, single center, observational setting. Patients with CRC who fulfill the
      inclusion criteria will be further evaluated after written informed consent. Kidney function
      and the CRC progression will be followed according to the current medical standards. If a
      significant change in cystic lesions is observed, further evaluation and surgical
      intervention, if indicated, will be initiated by the primary physician in charge. Testing
      will be performed upon study entry and after 12 months according to the following schedule:

        -  Blood-sampling

        -  CT

        -  fMRI

        -  renal CEUS

        -  chart review Two study physicians independently will review the CEUS and functional MRI
           images of the patients. The reviewers will be aware of study design but will be blinded
           to the clinical information of the CT findings. The scoring system for image
           interpretation will be based on the Bosniak cyst classification.
    

Intervention name(s): Blood/urine sampling; Conventional routine CT examination; Contrast-enhanced renal ultrasonography (CEUS); Functional MRI
Intervention type(s): Other; Other; Other; Other
Intervention description(s): Routine chemistry profile; Standard diagnostic examination; Study-specific diagnostic examination; Study-specific diagnostic examination
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients who were referred to the outpatient clinic of the Department of Nephrology or to
        the Department of Urology, Bern University Hospital for the clarification of a complex
        renal cyst/lesion and already underwent or will undergo a standard CT examination or
        patient who where accidentally diagnosed with a complicated renal cyst/lesion from the
        Department of Nephrology, Urology or Radiology (with CT imaging)
      
Keywords: Diffusion Magnetic Resonance Imaging; Medical Sonography; Computed Tomography, X-Ray