Espectroscopia de prótons e perfusão por ressonância magnética na avaliação dos tumores do sistema musculoesquelético

Abstract

OBJETIVO: Avaliar a espectroscopia de prótons e o estudo dinâmico do contraste por ressonância magnética na diferenciação dos tumores musculoesqueléticos benignos e malignos. MATERIAIS E MÉTODOS: Foram estudados 55 pacientes com tumores musculoesqueléticos (27 malignos e 28 benignos). Os exames foram realizados em aparelho de ressonância magnética de 1.5 T com protocolo convencional e espectroscopia de prótons com TE de 135 ms. O estudo dinâmico do contraste foi adquirido pela sequência T1 gradiente-eco após a administração intravenosa de gadolínio. Curvas de intensidade de sinal versus tempo e valores de slope foram calculados. A análise estatística foi realizada pelo teste de Levene, seguido pelo teste t de Student, além dos testes qui-quadrado de Pearson e exato de Fischer. RESULTADOS: A sensibilidade, especificidade e acurácia da espectroscopia de prótons foram, respectivamente, de 87,5%, 92,3% e 90,9% (p < 0,0001). Além disso, houve significativa diferença entre o valor quantitativo da curva entre as lesões benignas (média de 27,5% por minuto) e malignas (média de 110,9% por minuto) (p < 0,0001). CONCLUSÃO: Os estudos quantitativo e qualitativo da análise dinâmica do contraste por ressonância magnética associados à presença do pico de colina são úteis na diferenciação dos tumores musculoesqueléticos em benignos e malignos.

Functional magnetic resonance imaging in oncology: state of the art

“…Such methods are not intrinsically molecular, but allow for an indirect evaluation of molecular processes that affect the blood flow(13). The quantitative and qualitative dynamic analyses of the MRI contrast enhancement may also be useful in the differentiation of benign from malignant musculoskeletal system tumors ( 14 ) . Nowadays a very promising perfusion MRI technique without the utilization of paramagnetic contrast is available.…”

“…The conventional dynamic MRI technique is based on the concept of development of new vessels (angiogenesis) associated with increased blood flow and vessels permeability, which constitute essential conditions for metastatic dissemination of malignant tumors ( 14 , 16 , 17 ) . The microvascular structure of the tumor constitutes a relevant prognostic factor, and perfusion MRI can provide information about this special characteristic in a noninvasive way ( 13 ) .…”

“…The distribution of the contrast medium in the intra- and extravascular regions will depend upon some factors such as blood flow, vascular permeability and interstitial diffusion capacity. This technique can be performed with T1-weighted gradient-echo (GRE-T1) and T2-weighted* sequences ( 13 , 14 ) . The GRE-T1 sequences can more appropriately characterize the alterations in vessels permeability and extravasation to the extravascular space and are indicated for the evaluation of extracranial regions.…”

“…The T2-weighted* sequences are more frequently indicated for evaluation of the brain and determine the blood flow volume and capillary tissue perfusion ( Figure 6 ). With those sequences it is possible to perform qualitative, semi-quantitative and quantitative measurements ( 13 , 14 ) . Qualitative measurements can be obtained by means of signal intensity-time curves, often utilized in the evaluation of breast carcinomas ( Figure 7 ).…”

Espectroscopia de prótons e difusão na avaliação dos tumores do sistema musculoesquelético

“…Other methods originating from other areas of research have started to be utilized, such as proton magnetic resonance spectroscopy and perfusion magnetic resonance imaging, originally utilized for investigating the central nervous system (4,5) . In an interesting article published in the present issue of Radiologia Brasileira, Costa et al describe the utilization of proton magnetic resonance spectroscopy and perfusion magnetic resonance imaging in the detection and differentiation of benign and malignant tumors, with spectroscopy demonstrating sensitivity, specificity and accuracy of 87.5%, 92.3% and 90.9%, respectively, while the perfusion curve showed a statistically significant difference between benign and malignant tumors (6) . This article corroborates other studies published in specialized journals, showing that such advanced MRI techniques may be instrumental in increasing the diagnostic accuracy in the differentiation of benign from malignant lesions, aiding the radiologist in the analysis of images acquired with conventional methods (7) .…”