Spot Diagnosis

Giant cell tumors - dynamic curves

This patient has a typical giant cell tumor in the lower end of the radius on the plain radiograph (Fig. 1). The T1W coronal (Fig. 2) and T2W sagittal (Fig. 3) images, show typical features. On the contrast enhanced study, the lesion shows homogeneous enhancement (Fig. 4). The dynamic study however shows that the lesion is vascular with rapid uptake and wash-out, paralleling the artery (Fig. 5).

This is a curve usually seen with malignant tumors, but also seen in the vast majority of virgin and especially recurrent tumors.

Subependymal heterotopia

This is a 12-years old girl, previously asymptomatic, with a history of fever followed by three episodes of seizures.

The MRI images (Figs. 1-3) show a smooth, nodular area, isointense to grey matter, on all pulse sequences, along the margin of the atrium of the right lateral ventricle. The closest differential diagnosis is a hamartoma of tuberous sclerosis, but this would be irregular with its long axis perpendicular to the ventricular wall and will not be isointense to grey matter.

MRI arthrography of the hip in femoro-acetabular impingement (FAI)

This is an article by Pfirrmann et al from Zurich, describing the differences in the Cam and Pincer types of femoro-acetabular impingement (FAI) in the September issue of Radiology.

In Cam type of FAI, there are abnormal labral changes along the anterior and antero-superior aspects with an abnormal alpha angle due to non-sphericity and an abnormal osseous bump at the head-neck junction. In the Pincer type of FAI, there are abnormal labral changes postero-inferiorly, with over-riding of the anterior acetabulum or an increased acetabular depth.

The article nicely mentions these differences and findings and describes the various related issues.

This patient with a Cam type FAI shows acetabular ossicles on the plain radiograph (Fig. 1), which is otherwise normal. The MRI arthrogram shows an antero-superior labral tear (Figs. 2, 4 - red arrows). An osseous bump is noted at the head-neck junction on the oblique axial image (Fig. 3).

Giant cell tumor - distal radius

This 25-years old lady showed an expansile, osteolytic, trabeculated lesion involving the epiphysis and metaphysis of the distal end of the radius, with a narrow zone of transition, the lesion extending upto the articular surface (Figs. 1, 2). There appeared to an anterior cortical break (Fig. 2). The MRI showed the lesion to be isointense on the T1W images (Fig. 3) and mildly hyperintense on the T2W images (Fig. 4) with a focal area of necrosis (red arrowhead). The anterior cortical break (red arrow) and extra-osseous extension of the soft tissue, was well appreciated on the T2W sagittal image (Fig. 4).

Neuroradiology case of the week

Every Friday, we will be putting up a new Neuroradiology case

1. Neuronal ceroid lipofuscinosis

Neuronal ceroid lipofuscinosis (NCL)

This is a 5-years old boy, normal at birth with regression of social and language milestons in the last few months with loss of vision, due to retinitis pigmentosa.

An MRI was performed, which shows moderate cerebral and cerebellar atrophy with a reduction in the volume of the cerebral white matter (Figs. 1, 2). The T2W images demonstrate confluent hyperintense signal in the periventricular zones along the margins of the lateral ventricles and optic radiations extending into the lateral geniculate bodies (Figs. 3-5). Ill-defined T2 hyperintense signals are noted in the deep white matter. Short TE spectra (Fig. 6) suggestive of increase in myoinositol and glutamine-glutamate at 3.56 and 3.6-3.8 ppm are seen. Choline/creatine ratios are relatively well preserved. The NAA/creatine ratios are slightly decreased. Long TE spectra (FIg. 7)  do not show significant lactate peak.

In the given clinical setting, these findings are suggestive of neuronal ceroid lipofuscinosis.


 

High-resolution MRI lymphangiography

A new technical innovation from Germany, by Lohrmann C et al, in the August issue of the AJR, shows how we can perform high-resolution MRI lymphangiography using gadodiamide (Omniscan), by injecting it into the web-spaces of the toes and imaging approximately 45-60 minutes later. The lymphatic vessels are very well seen and patients with lymphedema can thus be imaged.

Considering that traditional lymphangiography is so difficult nowadays to perform, especially due to the lack of availability of Lipiodol, this should be an attactive technique to use.

Simple bone cyst with fracture

One of the complications of a simple bone cyst is fracture. The fracture is often transverse and one sign that is touted is the "fallen fragment sign", due to fragments of bone that are seen in the dependent portion on erect images (Fig. 1) - usually in the inferior aspect of the cyst. Even on MRI, which is performed in the supine position, bone fragments may be seen in the inferior aspect (Figs. 2, 3).

Steroid injection into a simple bone cyst

This 11-years old girl had left hip pain. The plain radiograph showed a mildly expansile osteolytic lesion with a narrow zone of transition in the distal neck (Fig. 1). A simple bone cyst was suspected and the CT (Fig. 2) and MRI (Figs. 3-5) confirmed this possibility.

In view of the age and location, the treating doctor decided to treat the patient conservatively and sent her for a CT-guided steroid injection. This was performed with CT fluroscopy control and after introducing a needle into the lesion (Fig. 6), a mixture of methylprednisolone and intravenous contrast was injected (Figs. 7, 8). Queried after a week, the patient confirmed relief from pain.

Head Injuries Lecture - Slides 40-43