1. Introduction

Patient M., 59 years old woman, complained of sleep disturbance, weakness, and numbness in the left extremities. She was admitted to hospital and further investigated. Mental state and consciousness are clear. Orientation in space and time is preserved. Critical thinking is intact. Neurological status is adequate.

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The patient had an ultrasound examination of the abdomen, retroperitoneum, small pelvis, thyroid and mammary glands. No masses were found in the areas examined. Laboratory tests (CBC, biochemistry, coagulation test, urinalysis) had no positive findings.

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Brain MRI was performed. In the right temporal region, at the level of the nuclei, a cystic-solid mass was showed, irregularly shaped, with rather distinct irregular contours, measuring up to 25x34x32 mm (Fig. 1), with inhomogeneous contrast enhancement, especially in the periphery, with marked perifocal edema and compression of the right lateral ventricle, the right half of the pons and the right optic tract and chiasma. In the occipital region on the right, a similarly structured round mass was seen, closely adherent to the skull, measuring up to 38x35x37 mm (Fig. 2), also with inhomogeneous contrast enhancement, predominantly along the periphery, and with marked perifocal edema. There is a strong displacement of the median structures from right to left up to 7 mm (Fig. 1).

2. Intraoperative Ultrasound Examination

2.1 Intraoperative B-mode and Color Doppler Ultrasound

After trepanation, intraoperative ultrasound was performed with Resona 7 (Mindray, China) using an intracavitary probe (V11-3HU). In the grey-scale image, a tumor with irregular, ill-defined borders, abnormally shaped and measuring 2.5 x 2.4 mm was seen at a depth of 1.5 cm. No color spots were detected in Color Doppler mode.

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2.2 Intraoperative contrast-enhanced ultrasound (CEUS)

For CEUS, 2 ml of prepared ultrasound contrast agent (USAc) "SonoVue" (Bracco, Italy) was used. Due to the small size of the trepanation window, the study was performed in longitudinal and transverse sections perpendicular to the brain surface. Visualization was performed immediately after injection of USAc into the cubital vein (Fig. 3).

The time-intensity curve (TIC) of focal mass was done for quantitative analysis. It was characterized by a rapid increase followed by a plateau phase. Contrast agent in ROI 2 (yellow) was detected at a level below 3 dB (Fig. 4).

3. Biopsy result

A biopsy was done immediately after the CEUS examination. According to the results of the histological analysis, a diagnosis of malignant neoplasm was made, exceeding the one or more of the above localizations. The morphology and immunophenotype of the tumor correspond to a G4 WHO astrocytoma (glioblastoma) (Fig. 5). IDH1 is positive.

4. Discussion

The use of ultrasound, particularly CEUS, in the evaluation of brain tumors is an evolving area of medical imaging. CEUS improves the ability to differentiate between cystic and solid masses, which is crucial for diagnosis and treatment planning. Cystic tumors often have different implications compared to solid tumors, including variations in treatment approaches and prognostic outcomes ^[1].

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In clinical practice, standard B-mode ultrasound can provide valuable information about the structure of brain masses, but the addition of contrast agents improves visualization of vascularity and perfusion characteristics ^[2]. This can help to more accurately assess the nature of the tumors, guiding further management decisions such as biopsy or surgery.

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The integration of CEUS into clinical practice requires training and expertise, as well as an understanding of its limitations2. For instance, while CEUS can provide valuable information about vascularity, it cannot replace MRI in terms of spatial resolution and detailed anatomical information. Research into the use of CEUS in brain tumors is ongoing, and advancements in contrast agents and imaging technology may further improve its utility. There is potential for CEUS to play a more important role in monitoring treatment response and assessing tumor recurrence ^[3].

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Overall, while MRI remains the gold standard for brain imaging, the integration of ultrasound techniques, including contrast-enhanced mode, can complement existing diagnostic tools and improve patient outcomes through more precise evaluations.

References:

[1]. Tao AY, Chen X, Zhang LY, Chen Y, Cao D, Guo ZQ, Chen J. Application of Intraoperative Contrast-Enhanced Ultrasound in the Resection of Brain Tumors. Curr Med Sci. 2022 Feb;42(1):169-176. doi: 10.1007/s11596-022-2538-z. Epub 2022 Feb 5. PMID: 35122612.

[2]. Wang J, Yang Y, Liu X, Duan Y. Intraoperative contrast-enhanced ultrasound for cerebral glioma resection and the relationship between microvascular perfusion and microvessel density. Clin Neurol Neurosurg. 2019 Nov; 186:105512. doi: 10.1016/j.clineuro.2019.105512. Epub 2019 Sep 3. PMID: 31585336.

[3]. Prada F, Perin A, Martegani A, Aiani L, Solbiati L, Lamperti M, Casali C, Legnani F, Mattei L, Saladino A, Saini M, DiMeco F. Intraoperative contrast-enhanced ultrasound for brain tumor surgery. Neurosurgery. 2014 May;74(5):542-52; discussion 552. doi: 10.1227/NEU.0000000000000301. PMID: 24598809.