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ECR 2019 / C-1999
Role of Multiparametric MRI in Brainstem Lesions
Congress: ECR 2019
Poster No.: C-1999
Type: Scientific Exhibit
Keywords: Neuroradiology brain, MR-Diffusion/Perfusion, MR-Spectroscopy, Diagnostic procedure, Cancer, Inflammation
Authors: M. Harley, M. D. Patel, M. Bowen, W. Muhammad, S. Jacob, M. Douglas, I. Ughratdar, J. Herbert, V. Sawlani; Birmingham/UK
DOI:10.26044/ecr2019/C-1999

Results

Case 1

  • A previously well 20 year-old  presented in August 2016 with acute ataxia, slurred speech, deafness and visual disturbance following recent travel. On examination there was a complex  ophthalmoplegia, horizontal nystagmus, sensorineural deafness, cerebellar signs and spastic limbs.
  • Conventional MRI suggested a diagnosis of low grade brainstem glioma . The oncologist recommended radiotherapy given the large infiltrative lesion.
  • Multiparametric MRI was performed; findings were not consistent with low grade glioma due to normal MI/Cr and the glutamine shoulder, neither were they consistent with high grade glioma due to lack of enhancement, low rCBV, high ADC and normal choline. This along with the acute presentation raised the possibility of an inflammatory lesion. Biopsy was avoided and the patient was treated with intravenous methylprednisolone with an improvement in symptoms and discharged on prednisolone. 
Fig. 1: Case 1. Upper Row. Conventional MRI Findings: Axial T2W, sagittal and coronal FLAIR, and axial post-contrast T1W sequences, showed a diffuse high signal lesion in the pons with no enhancement post-contrast. Lower Row. Multiparametric MRI: DWI showed free diffusion with high ADC throughout the lesion. MRS showed a normal myo-inositol (MI) and low MI/Cr ratio, a normal Cho/Cr ratio, a normal N-acetylaspartate/creatine (NAA/Cr) ratio and minimally raised glutamine and glutamate (2.3 ppm and 2.4 ppm). PWI (not shown) showed low rCBV compared to contralateral white matter.
References: University Hospitals Birmingham, University Hospitals Birmingham - Birmingham/UK
  • Follow-up MRI showed complete resolution. CSF analysis revealed antiganglioside antibodies and a final diagnosis of Bickerstaff brainstem encephalitis was made. 
Fig. 2: Case 1. Two-month follow-up showed lesion regression and normalisation of diffusion, and the patient had made a complete clinical recovery by three months.
References: University Hospitals Birmingham, University Hospitals Birmingham - Birmingham/UK

 

Case 2

  • A 43 year-old male with a 10-year history of pulmonary sarcoidosis on immunosuppression (azathioprine) presented with progressive headache, vomiting, ataxia and cerebellar signs in September 2016.
  • Conventional MRI showed a diffuse infiltrative lesion in the right middle cerebellar peduncle extending to the brainstem and right cerebellar hemisphere. Focal and discrete T2W hypointense areas were seen throughout the lesion. There was mild mass effect and multiple contrast-enhancing foci with few lesions showing central necrosis. 
  • Differential diagnoses included: a chronic infective lesion, a granulomatous lesion, high grade glioma and metastases. Biopsy was considered.
  • Multiparametric MRI was performed; findings were more in favour of inflammatory aetiology rather than a high-grade glioma. Neurosarcoid was a possibility.
Fig. 3: Case 2. Upper Row. Conventional MRI Findings: Axial and coronal T2W, axial FLAIR, and post-contrast T1W sequences, showing a diffuse infiltrative lesion with enhancing foci in the right cerebellar peduncle extending to the brainstem. Lower Row. Multiparametric MRI: PWI showed predominently low perfusion, with an rCBV <2 and the histogram did not show any significant increase in perfusion when compared to contralateral site. DWI showed focal areas of restricted diffusion. MRS (TE 35ms) showed moderately high Cho/Cr ratio (<2), near normal NAA/Cr and MI/Cr, presence of glutamate and glutamine at 2.4-2.6 ppm and large lipid peaks at 0.9 and 1.3 ppm suggesting necrosis. MRS with a TE 135ms showed slightly low NAA/creatine ratio and no presence of lactate.
References: University Hospitals Birmingham, University Hospitals Birmingham - Birmingham/UK
  • Biopsy was also performed and a tapering dose of oral prednisolone was commenced, during which neurological symptoms improved.
  • Follow-up MRI showed near complete resolution of the lesion. 
Fig. 4: Case 2. Three-month follow-up showed near complete resolution of the lesion.
References: University Hospitals Birmingham, University Hospitals Birmingham - Birmingham/UK

 

Case 3

  • A 65 year-old presented initially with headaches and right lower motor neurone facial palsy, with subsequent right abductor palsy as well as left trigeminal palsy.
  • Conventional MRI at the time revealed a well defined thick rim and nodular enhancing lesion at the ponto-medullary junction, with mild mass effect. 
  • The differential diagnoses included a chronic infective lesion, a granulomatous lesion and aggressive primary glial neoplasm. Initial biopsy was inconclusive.
  • Multiparametric MRI was performed to further characterise the lesion; findings were consistent with a high grade glioma rather than a granulomatous or infective lesion. In view of this, a decision to undergo further biopsy was overturned. The patient underwent radiotherapy.
Fig. 5: Case 3. Upper Row. Conventional axial /coronal post-contrast T1W sequences, showing a well-defined lesion at the ponto-medullary junction. Lower Row. Multiparametric MRI: PWI showed high perfusion (>2). DWI showed relative restricted diffusion (<1000). MRS showed a high Cho/Cr (>2), low NAA/Cr ratio, and presence of lipid and lactate.
References: University Hospitals Birmingham, University Hospitals Birmingham - Birmingham/UK
  • Follow-up MRI showed a slight reduction in the size of the lesion. 
Fig. 6: Case 3. Three-month follow-up showed a slight reduction in the size of the lesion.
References: University Hospitals Birmingham, University Hospitals Birmingham - Birmingham/UK

 

 

Case 4

  • A 64 year-old woman presented in June 2015 with headaches, vertigo and vomiting. She was ataxic, had a right abductor palsy and left inferior rectus paresis.
  • Conventional MRI showed a well-defined T2W hyperintense lesion  in the medulla with no peri-lesional oedema  or contrast enhancement and no significant mass effect.
  • Findings were suspicious of a low grade tumour or inflammatory lesion. Biopsy was considered too  dangerous, however a decision was made to further characterise the lesion using multiparametric MRI.
  • Multiparametric MRI findings suggested an inflammatory lesion rather than low grade glioma. 
Fig. 7: Case 4. Upper Row. Conventional axial contrast T1W and sagittal FLAIR sequences, showing a well-defined lesion in the medulla. Lower Row. Multiparametric MRI: PWI showed low perfusion. DWI showed high diffusion (>1000). MRS showed a minimally raised Cho/Cr, near normal NAA/Cr, low MI/Cr, and absence of lipid and lactate.
References: University Hospitals Birmingham, University Hospitals Birmingham - Birmingham/UK
  • Follow-up MRI at three months showed that the lesion was resolving.
Fig. 8: Case 4. Three-month follow-up showed that the lesion was resolving.
References: University Hospitals Birmingham, University Hospitals Birmingham - Birmingham/UK
  • Follow-up imaging at six months showed that the lesion had almost completely resolved, suggesting that it was likely to be inflammatory in nature.
Fig. 9: Case 4. Six-month follow-up showed that the lesion had almost completely resolved.
References: University Hospitals Birmingham, University Hospitals Birmingham - Birmingham/UK

 

Discussion

 

Combining conventional MR imaging with multiparametric MRI successfully predicted the diagnosis in these four patients, which was subsequently confirmed through biopsy (n=1), specific serological markers (n=1) or treatment response (n=2). Three cases were accurately diagnosed as inflammatory and one case as neoplastic. There is evidence that the individual parameters of diffusion, perfusion and spectroscopy MR imaging in isolation can be helpful in diagnosis, however by combining both spectroscopy and perfusion the sensitivity and specificity has shown to increase to 72% and 92% respectively.1 There are issues in analysing results from MR spectroscopy in tumours and inflammation and there may be overlapping features.2 However if there is high order shimming, a consistent protocol and accurate interpretation of the spectra,3 in addition to correlation with diffusion and perfusion imaging, the sensitivity and specificity can increase even further. 

 

Fig. 10: Summary of results: Multiparametric MRI features distinguishing inflammatory lesions from neoplasm.
References: University Hospitals Birmingham, University Hospitals Birmingham - Birmingham/UK

 

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