Diffusion-weighted imaging (DWI) in lymph node staging for prostate cancer

Abstract

In patients with prostate cancer, the presence of lymph node (LN) metastases is a critical prognostic factor and is essential for treatment planning. Conventional cross-sectional imaging performs poorly for nodal staging as both computed tomography (CT) and magnetic resonance imaging (MRI) are mainly dependent on size and basic morphological criteria. Therefore, extended pelvic LN dissection (ePLND) remains the gold standard for LN staging, however, it is an invasive procedure with its own drawbacks, thus creating a need for accurate preoperative imaging test. Incorporating functional MRI by using diffusion-weighted MRI has proven superior to conventional MRI protocol by means of both qualitative and quantitative assessment. Currently, the increased diagnostic performance remains insufficient to replace ePLND and the future role of DWI may be through combination with MR lymphangiography or with novel positron emission tomography (PET) tracers. In this article, the current state of data supporting DWI in LN staging of patients with prostate cancer is discussed.

Whole-body magnetic resonance imaging (WB-MRI) reporting with the METastasis Reporting and Data System for Prostate Cancer (MET-RADS-P): inter-observer agreement between readers of different expertise levels

“…Second, the literature on response assessment is dominated by studies using RECIST 1.1 criteria [ 18 ], which depend primarily on changes in lesion dimensions and are applicable to primary, nodal, and visceral sites, but not for bone metastases. As these same criteria are followed for primary, nodal, and visceral sites under MET-RADS-P, the moderate to substantial inter-observer agreement seen in the primary/dominant RAC assessment of node regions likely reflects known difficulties in assessing nodes with MRI, which is dependent on nodal size assessments [ 19 , 20 ]. Third, for interpretation of bone metastases, the MET-RADS-P guidelines consider alterations in both size and ADC values, providing extra information that likely increases the performance and inter-observer agreement for bone metastases.…”

The prognostic nomogram including MRI for locally advanced prostate cancer treated by radical prostatectomy

“…Furthermore, bilateral LNM were detected more frequently in high‐risk (16%) than intermediate‐risk (1.3%) cases, suggesting an association with aggressive PCa 31 which identified with our bPFS result. Conventional MRI based on size and basic morphological criteria showed a poor result about nodal staging, 32 however, mp‐MRI could improve diagnostic performance about cN staging by using DWI correlated with anatomical T2 images 33 …”

Multiparametric magnetic resonance imaging of the prostate: Lights and shadows

“…Functional sequences of mpMRI has been advocated for identifying malignant nodes, particularly using ADC values, but conflicting results were reported because of significant overlap between benign and malignant LN ADC. 23 New node staging perspectives include the use of ultrasmall superparamagnetic particles of iron oxide (USPIOs), phagocytosed by macrophages in circulation, and are taken up by lymphatics into lymph nodes, in order to perform a magnetic resonance lymphography (MRL). 24 In this contest, role of DWI in combination with MRL could apport further benefits showing sensitivity values 25 between 65% and 75% and specificity values of 93%-96%.…”