Accuracy of Magnetic Resonance Imaging (MRI) to identify pseudocapsule integrity in renal tumors

Emanuela Altobelli1, Valeria Panebianco2, Rocco Papalia1, Maurizio Del Monte2, Riccardo Mastroianni1, Eliodoro Faiella1, Rosario Francesco Grasso1, Gianluca Muto3, Chiara Taffon 1, Federico Germinale 1, Alessandro Giacobbe4, Giovanni Muto4
  • 1 Università Campus Bio-Medico (Roma)
  • 2 Università degli Studi di Roma "La Sapienza" (Roma)
  • 3 Azienda ospedaliero-universitaria Careggi (Firenze)
  • 4 Humanitas Gradenigo (Torino)


Small renal masses detection is increasing with the use of cross-sectional imaging and the desirable treatment, when technically feasible, is nephron sparing surgery (NSS).
A pseudocapsule (PC) surrounds most masses and a method to identify its integrity would aid to keep a safe surgical margin improving excisional precision.
To evaluate MRI likelihood scale of detection of renal tumor PC infiltration.

Materials and Methods

From January 2016 to September 2017, 58 consecutive patients with renal masses were enrolled in the study. Exclusion criteria included gross hematuria. All patients underwent MRI prior to tumor surgery. Data were collected in a prospective maintained dataset. The patients underwent MRI exams using high resolution protocol including morphological sequenceses (T2 & T1 imaging), Diffusion MRI (DWI) and Dynamic Contrast Enhanced MRI (DCE).
Two experienced Radiologists evaluated the MRI based on a predefined algorithm in advice with Urologists , and applied a score to tumor PC (MRIpC): MRIpC1) intact and continues ; MRIpC2) infiltrated and uninterrupted; MRIpC3) infiltrated and interrupted; NoMRIpC) absent PC.
Figure 1.
Similarly, two experienced pathologists reported PC integrity according to the Renal Tumor Capsule Invasion Scoring System (i-Cap).
The MRIpC score was compared to histology.


There is no standardization in terms of semetiocs MRI. On MRI, a PC was described in 45 cases and confirmed at pathology. It was absent in 3 cases (all ccRCC). In 1 patient, a very thin PC was identified at pathology and not reported on MRI (pT3a G3 renal cell carcinoma). On MRI, the PC was intact in 28 cases, infiltrated in 9, disrupted in 14 and absent in 7 cases.
On pathology, a correlation between MRI and i-Cap was found in 53 lesions (91.4%).
The PC disruption was observed at the same level reported on MRI images.
Sensitivity and specificity were 97.92% and 60%, respectively. PPV and NPV were 92.16% and 85.71 %.
Absence and interruption of the PC and tumor volume correlated with high grade disease (G3-G4).


Standard NSS requires a minimal layer of normal-appearing parenchyma.

Nevertheless tumor enucleation showed excellent results in the treatment of pT1 renal tumors.

A detailed preoperative identification of PC integrity can drive indications to NSS versus enucleation.

Our findings show how preoperative MRI can identify PC status.

Measuring the length of the integral PC and knowing where to expect an interruption/invasion, we can have an imaging-guided landmark to figure out where a minimal margin could be oncologically safer.


Our findings show how preoperative MRI can identify PC status helping optimizing surgical procedures selection.