Prenatal MR Imaging Phenotype of Fetuses with Tuberous Sclerosis: An Institutional Case Series and Literature Review

Abstract

Background and purpose: Most patients with tuberous sclerosis complex (TSC) do not receive prenatal diagnosis. Our aim was to describe MR imaging findings to determine the following: 1. Whether normal fetal MR imaging is more common in fetuses imaged at ≤24 weeks' gestation compared with >24 weeks 2. The frequency of cardiac rhabdomyoma 3. The range of MR imaging phenotypes in fetal tuberous sclerosis complex.

Materials and methods: Our institutional fetal MR imaging data base was searched between January 1, 2011 and June 30, 2021, for cases of TSC confirmed either by genetic testing, postnatal imaging, postmortem examination, or composite prenatal imaging findings and family history. A MEDLINE search was performed on June 8, 2021.

Results: Forty-seven published cases and 4 of our own cases were identified. Normal findings on fetal MR imaging were seen at a lower gestational age (mean, 24.7 [SD, 4.5 ] weeks) than abnormal findings on MR imaging (mean, 30.0 [SD, 5.3] weeks) (P = .008). Nine of 42 patients with abnormal MR imaging findings were ≤24 weeks' gestation. Subependymal nodules were present in 26/45 cases (57.8%), and cortical/subcortical lesions, in 17/46 (37.0%). A foramen of Monro nodule was present in 15 cases; in 2/7 cases in which this was unilateral, it was the only abnormal cerebral finding. Cardiac rhabdomyoma was absent in 3/48 cases at the time of fetal MR imaging but was discovered later. Megalencephaly or hemimegalencephaly was observed in 3 cases.

Conclusions: Fetuses with abnormal cranial MR imaging findings were older than those with negative findings. Fetal hemimegalencephaly and megalencephaly should prompt fetal echocardiography. Cardiac rhabdomyoma was not always present at the time of fetal MR imaging.

FIG 1.

Case ascertainment process.

FIG 2.

Thirty-two to 40 weeks’ gestation. 3T, single-shot T2-weighted EPI shows the foramen of Monro dominant nodule/enlarged GE (A and B) and cortical tuber (C).

FIG 3.

Twenty-five weeks’ gestation. A 1.5T, single-shot T2-weighted EPI (A) shows the right foramen of Monro dominant nodule/enlarged GE and the normal GE on the left. T2*-weighted image (B) demonstrates no blood products in the mass.

FIG 4.

Twenty-two weeks’ gestation. A 1.5T single-shot T2-weighted EPI demonstrates hemimegalencephaly and a dominant ipsilateral mass representing a possible coexistent subependymal giant cell astrocytoma. This was initially interpreted on screening US as a parenchymal hemorrhage. After the iuMR, dedicated fetal echocardiography the following day identified a single small rhabdomyoma.