Role of in-phase and out-of-phase chemical shift MRI in differentiation of non-neoplastic versus neoplastic benign and malignant marrow lesions

Abstract

Objective: To determine its ability of in-phase (IP) and out-of-phase (OOP) chemical shift imaging (CSI) to distinguish non-neoplastic marrow lesions, benign bone tumours and malignant bone tumours.

Methods: CSI was introduced into our musculoskeletal tumour protocol in May 2018 to aid in characterisation of suspected bone tumours. The % signal intensity (SI) drop between IP and OOP sequences was calculated and compared to the final lesion diagnosis, which was classified as non-neoplastic (NN), benign neoplastic (BN) or malignant neoplastic (MN).

Results: The study included 174 patients (84 males; 90 females: mean age 44.2 years, range 2-87 years). Based on either imaging features (n = 105) or histology (n = 69), 44 lesions (25.3%) were classified as NN, 66 (37.9%) as BN and 64 (36.8%) as MN. Mean % SI drop on OOP for NN lesions was 36.6%, for BN 3.19% and for MN 3.24% (p < 0.001). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of CSI for differentiating NN from neoplastic lesions were 65.9%, 94.6%, 80.6%, 89.1%% and 87.4% respectively, and for differentiating BN from MN were 9.1%, 98.4%, 85.7%, 51.2 and 53.1% respectively.

Conclusion: CSI is accurate for differentiating non-neoplastic and neoplastic marrow lesions, but is of no value in differentiating malignant bone tumours from non-fat containing benign bone tumours.

Advances in knowledge: CSI is of value for differentiating non-neoplastic marrow lesions from neoplastic lesions, but not for differentiating benign bone tumours from malignant bone tumours as has been previously reported.

Figure 1.

A 41-year-old female with previous history of breast cancer and abnormality in the right radius on bone scintigraphy. (a) Coronal T₁W TSE, (b) sagittal T₂W FSE and (c) axial SPAIR MR images of the right forearm demonstrate an extensive area of abnormal marrow SI in the proximal radius (arrows) concerning for metastatic infiltration. (d) IP and (e) OOP CSI demonstrates marked reduction of SI on the OOP sequence measured at 50.6%, the features being consistent with hyperplastic red marrow. CSI, chemical shiftimaging; IP, in-phase; OOP, out-of-phase; SPAIR, spectralattenuated inversion recovery; T₁WFSE, T₁weighted fast spin echo.

Figure 2.

A 28-year-old male with right shin pain. (a) AP radiograph of the right lower limb demonstrates poorly-defined marrow sclerosis in the proximal tibial diaphysis (arrows). (b) CoronalT₁W TSE (c) and axial SPAIR MR images of the right calf demonstrate an extensive marrow lesion in the proximal tibial diaphysis (arrows) with morphological characteristics of an atypical cartilaginous tumour. (d) IP and (e) OOP CSI demonstrates 1.1% SI drop on the OOP sequence consistent with a marrow replacing lesion. AP, anteroposterior; CSI,chemical shift imaging; IP, in-phase; OOP, out-of-phase; SPAIR, spectralattenuated inversion recovery; T₁WFSE, T₁weighted fast spin echo.

Figure 3.

A 53-year-old female with a long-standing lesion in the right femur. (a) Coronal T₁W TSE MR image demonstrates a lobular intermediate SI lesion (arrow) expanding the proximal femoral metadiaphysis. (b) IP and (c) OOP CSI demonstrates 17.2% SI drop on the OOP sequence consistent with marrow infiltration. Imaging diagnosis of fibrous dysplasia. CSI, chemical shiftimaging; IP, in-phase; OOP, out-of-phase; SI, signal intensity; T₁W FSE, T₁weighted fast spin echo.

Figure 4.

An 18-year-old male who presented with right buttock pain. (a) Coronal T₁W TSE and (b) axial PDW FSE MR images demonstrate an expansile lesion containing a fluid level (arrow) in the right ischium. (c) IP and (d) OOP CSI demonstrates 7.1% SI drop on the OOP sequence consistent with marrow infiltration. Histological diagnosis of aneurysmal bone cyst. IP, in-phase; OOP,out-of-phase; PDW, proton density weighted; T₁W, T₁weighted; TE, echo time; TR,repetition time.

Figure 5.

A 28-year-old male who presented with right shoulder pain. (a) AP radiograph shows a sub-articular lytic lesion (arrows) in the medial aspect of the humeral head. (b) Coronal T₁W TSE and (b) sagittal T₂ FSE MR images demonstrate a heterogeneous intermediate SI lesion containing areas of low SI consistent with chronic haemorrhage (arrows) suggestive of a giant cell tumour. (d) IP and (e) OOP CSI demonstrates 4.7% SI drop on the OOP sequence consistent with marrow infiltration. Histological diagnosis of giant cell tumour. AP, anteroposterior; CSI,chemical shift imaging; IP, in-phase; OOP, out-of-phase; SI, signal intensity; T₁W FSE, T₁weighted fast spin echo.

Figure 6.

A 33-year-old female with a previous history of leukaemia and new right shin pain. (a) Coronal T₁W TSE, (b) sagittal T₂W FSE and (c) axial SPAIR MR images of the right proximal tibia demonstrate an extensive area of abnormal marrow SI (arrows) associated with extra-osseous extension (arrowhead-c). (d) IP and (e) OOP CSI demonstrates 9.8% SI drop on the OOP sequence consistent with marrow infiltration. Biopsy confirmed recurrent leukaemia. AP, anteroposterior; CSI,chemical shift imaging; IP, in-phase; OOP, out-of-phase; SI, signal intensity; SPAIR,spectral attenuated inversion recovery; T₁WFSE, T₁weighted fast spin echo.

Figure 7.

Boxplot of % SI drop for different lesion types. NEO-BENIGN, neoplastic benign lesions; NEO-MALIG, neoplasticmalignant lesions; NN, non-neoplastic lesions; SI,signal intensity.