A common understanding among physicians, radiologists, surgeons and interventionists is that contrast enhancing tumours on MRI are hyper vascularity as opposed to non enhancing or mildly enhancing ones.

This, however is only partially correct, enhancing tumours not necessarily being hyper vascular.

Visual assessment of contrast enhancement of tumours as seen on MRI depends on many things..

e.g..

1. Amount of contrast given
2. Delay between contrast injection and image acquisition
3. presence of abnormal ‘leaky’ intratumoral vessels
4. presence of contrast ‘pools’ in the tumour
5. presence on intratumoral AV shunts
6. type of sequence and various parameters utilised

etc.

A case below illustrates our facts;

This was a female patient with two episodes of epistaxis. Nasal examination found a left sided polyp.

An MRI was done and showed an enhancing tumour.

A biopsy was done which showed spindle cell tumour probably angioleiomyoma

Prior to surgery, the ENT surgeon asked for embolization, considering the MRI and the biopsy report.

However, angiogram showed only a mild vascularity, with very small feeders from left internal maxillary artery. Hence, embolizaation was abandoned; the patient was operated upon and near total tumour removal achieved with mild and easily controllable blood loss.

Fig 1: Coronal T1WI and fat sat axial T2WI show left nasal tumor, iso –hypointense on t1 and apparently hyperintense on the t2WI

Fig 2: Coronal fat sat post gad T1WI show enhancement of the tumour – apparently considered hyper vascular

Fig 3: Histopathology slides  (microscopy and IHC) and reports

Fig. 4: left ECA angiogram shows the mildly vascular tumor

Fig 6: coronal fat sat t2WI shows that the tumor is isointense to gray matter

Two important sequences are: t2Wi and DWI;

t2 hyperintensse images tend to have high vascularity and tumors with high difusivity also tend to have higher vascularity.

The lesion in our case was wrongly interpreted as hyperintense on t2Wi as only fat sat images were done…and no comparision with cortex was done probably.

DWI is a sequence most MRI centers still do not perform for PNS lesions, though it has shown its utility beyond doubt.