Spot Diagnosis

MDCT for assessing pancreatico-biliary union

This article, by Itoh S et al , in the September issue of the AJR, shows how MDCT (using 4-slice) can depict the pancreatico-biliary ductal anatomy exceptionally well. This allows the diagnosis of the abnormal channel, especially in patients with choledochal cysts.

Because of the superior spatial resolution with multi-slice scanners, it is highly likely that the results with MSCT for this particular purpose, will be better than MRCP.

We have had a similar experience on our 64-slice CT. This is a child with a choledochal cyst (Fig. 1), where the abnormal pancreatico-biliary channel is extremely well seen (Figs. 2, 3).

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.

Solitary pulmonary nodule lecture - slides 7-11

Cervical vertebra biopsy

This 24-yeras old student had neck pain. An MRI revealed a C4 vertebral lesion. A contrast-enhanced CT scan prior to the biopsy showed an expansile osteolytic lesion involving the body and pedicle (Figs. 1, 2) with abnormal soft tissue. Under CT guidance, a core biopsy was performed, both of the soft tissue as well as from within the lesion (Figs. 3, 4).

Adequate tissue was obtained, which was reported to be tuberculosis.

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).

Solitary pulmonary nodule lecture - slides 4-6

Radiofrequency ablation (RFA) of a lung tumor

This is a 78-years old man, who had a 3.8cm sized mass in the left upper lobe (Fig. 1), which was proven to be a squamous cell carcinoma. There was marked surrounding emphysema and though the lesion was a T1 lesion, with no adenopathy or evidence of spread elsewhere on a PET study, he was not considered to be a candidate for surgery.

He was referred for a radiofrequency ablation (RFA). We had to make sure that we did not penetrate the emphysematous lung. Using the CT fluoroscopy function, it was possible to find an oblique route into the centre of the lesion (Figs. 2-4) and the tines of the electrode were then deployed (Figs. 5,6). A successful ablation was obtained with peri-lesional ground-glass attenuation (Fig. 7).

There was no evidence of a pneumothorax, but a plain-radiograph (FIg. 8) obtained 24 hours later showed fluid-fluid levels, presumably due to hemorrhage into the bullae. The patient however was comfortable and was discharged with due precautions.

Neuroradiology case of the week

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

1. Neuronal ceroid lipofuscinosis