SOMATOM Sessions - Siemens Healthcare

Clinical Results Cardio-Vascular
Case 6
SOMATOM Defi nition Flash:
Pediatric Patient Without Sedation
and Breath-Holding
By Kaori Takada, MD* and Tomoko Fujihara**
* Department of Radiology, Sakakibara Heart Institute, Tokyo, Japan
**
Application Department CT Team, Customer Service Division, Siemens-Asahi Medical Technologies, Tokyo, Japan
HISTORY
A 4-year-old boy with Tetralogy of Fallot
(TOF, Fig.1), pulmonary atresia (PA)
and major aorto-pulmonary collateral
arteries (MAPCAs) was referred to the
radiology department of Sakakibara
Heart Institute for a follow-up examination
using a SOMATOM Definition Flash,
Dual Source CT in Flash Spiral mode
following treatment of his pulmonary
artery stenosis.
The patient was diagnosed shortly after
birth with TOF, PA, MAPCA. When he
was 10 months old, a stent was inserted
in the largest MAPCA and a central shunt
was placed when he was 16 months old.
When he was 2 years old, he underwent
right and left modified Blalock-Taussig
1
1 Ventricular septal defect that is one
characteristic of TOF.
shunt surgeries (therefore the subclavian
artery is connected with the pulmonary
artery) within 9 months. Then, at
the age of 3, an artificial vessel was constructed
from the right ventricle (RV)
to the pulmonary artery by palliative
Rastelli procedure.
The patient now underwent a percutanous
transluminal angioplasty (PTA)
of pulmonary artery. A low dose, Dual
Source CT scan in the Flash Spiral mode
was ordered to confirm his postoperative
condition, in particular concerning
the pulmonary circulation. The patient’s
weight was 15.6 kg (34.39 lb).
He was not sedated and no breath-hold
was needed during the scan. His mean
heart rate was 95 bpm.
DIAGNOSIS
The Dual Source CT images showed that
the RV-pulmonary artery conduit was
patent and that the anastomosis site
had no stenosis. Neither the right nor
the left pulmonary arteries (about
4 mm diameter) presented any significant
stenosis (Fig. 2).
A stent was confirmed in the biggest
MAPCA, which bifurcated from the
descending aorta at the level of the left
atrium. It went to the right superior and
inferior lung lobes, and connected one
artery originating from right central pulmonary
artery. Although the stent itself
was patent, a stenotic part was seen distal
of the stent (Fig. 3). The Dual Source
42 SOMATOM Sessions · May 2010 · www.siemens.com/healthcare-magazine
CT images revealed a tortuous artery
originating from a right subclavian artery
that supplied the right and left inferior
lung lobes. The left lung was perfused
mainly by the left central pulmonary
artery. The right middle lung lobe
was perfused by the large right inferior
diaphragmatic artery (its distal end was
connected to an artery originating from
the central pulmonary artery).
Incidentally, the right coronary artery
(RCA) was found to originate from the
aorta at the upper level of left coronary
artery, the left coronary cusp (Fig. 4),
which could neither be seen in the previously
performed catheter angiography
nor in a 16-MSCT examination.
Based on these findings a catheter PTA
of the pulmonary artery stenosis at the
distal part of the stent was planned.
COMMENTS
Dual Source CT Angiography has
emerged as an essential diagnostic tool
for the assessment of complex congenital
heart disease. Nevertheless, dose has
remained a concern, in particular when
referring pediatric patients for cardiac
CT. With the Flash Spiral mode of the
second generation Dual Source CT,
pediatric patients can be scanned at
ultra low dose, as in this case at 1.63
mGy (effective dose 0.644 mSv). Apart
from dose concerns, additional challenges
have been associated with imaging
pediatric congenital heart disease