Ultrasound vs. Magnetic Resonance Imaging in the Diagnosis of Placenta Accreta Spectrum

Abstract

PAS (Placenta Accreta Spectrum) is a rare, multifactorial, life-threatening condition for both the mother and the fetus, posing a diagnostic challenge for both expert and non-expert sonographers during the clinical monitoring of pregnancy. The aim of this work is to assess the prenatal diagnostic predictability of placenta accreta spectrum comparing two methods: ultrasound and magnetic resonance imaging. A prospective comparison was done over a 4-year period (2019–2022) between US and MRI diagnostic recognitions of PAS. Thirty-four cases prenatally were diagnosed by US аnd confirmed pathohistologically with complete agreement. Comparative diagnostic recognition was performed in 74 cases suspected for placenta praevia accreta by US, in 35 cases PAS were found, and 39 were excluded as normal placenta praevia. In 41 of all 74 cases, MRI was additionally performed. The US has done by one expert and the following markers for PAS were examined: loss of clear space, abnormal lacunae, subplacental hypervascularity, and bridging vessels. MRI diagnosis following standard protocols from more than one expert was made. The presented observation period was part of an 11-year prospective study (2012–2023) covering 61 cases of clinically and pathohistologically confirmed PAS. The results showed that MRI has a recognizability rate of 67.62% compared to ultrasound, which showed a 97.14% coincidence. The US methodology has significance detecting PAS and was primarily performed by one expert (p<0.001). MRI showed the same statistical significance in the diagnosis of placenta praevia and accrete (p<0.001). The comparative results for the diagnosis of placenta accrete were as follows: 90.00% sensitivity, 97.06% specificity, Positive Predictive Value – 96.43%, Negative Predictive Value – 91.67% for ultrasound examination. For MRI we found similar sensitivity 97.62%, but low specificity, positive predictive value and negative predictive value (5.36%, 69.49%, 50.00%, respectively). Ultrasound is a superior, accessible method for diagnosis of PAS. MRI is an additional method in the diagnosis of PAS and should be used selectively. Both methods have comparable sensitivity.