- Hematological malignancies represent a major indication for CT exploration in our imaging department.
- The patients undergoing CT exams are either at their initial assessment of disease status,
or reviewed for outcome reassessment in their follow-up. There is a wide age variability of the patients requiring a CT examination,
including children,
adults and elderly people.
Since most of the patients require regular CT follow-up studies,
there is major raising concern with reference not to harm these patients even more with unnecessary high radiation doses.
- Therefore,
since we use a CT scanner with iterative reconstruction (IR) capabilities,
we have used lower dose radiation exposure using IR,
trying to observe if there are any important diagnosis drawbacks related to an usual radiation regimen and standard filtered back projection images (FBP).
The rationale of our study relies on recent literature regarding the usefulness of IR use in patients with hematological diseases.
- One of the first papers studying the effect of using IR techniques has been published by AC Silva et al,
stating that ASIR reconstruction algorithm is a promising technique for providing diagnostic quality CT images at significantly reduced radiation doses.
A similar paper,
published by E.
Barnes presented preliminary experience of Mayo Clinic in using low-dose abdomen CT examinations with ASIR reconstruction,
showing the efficiency of this method in sharpening images,
without any reduction in lesion conspicuity or detection.
- M.
Meyer et al.
found that halving radiation dose and risk by iterative image reconstruction in whole-body CT for lymphoma staging proved beneficial.
- G.
Boning at al referred to the study of neuroendocrine tumors,
finding that in clinical practice,
adaptive statistical iterative reconstruction (ASIR) can be used to reduce radiation dose without sacrificing image quality and diagnostic confidence in staging CT of NET patients.
- Y.
Sagara at al have found that compared with routine-dose CT with FBP,
abdominal low-dose CT with ASIR significantly reduces noise,
thereby permitting diagnostic abdominal examinations with lower (by 23–66%) radiation doses and despite reduced image sharpness in average and small patients,
low-dose CT with ASIR had diagnostic acceptability comparable to that of routine-dose CT with FBP.
Similar findings have also been published by P Prakash et al.
- Similarly,
for chest CT studies,
S.
Singh et al.
have found that acceptable image quality can be obtained for chest CT images acquired at 40 mAs by using ASIR without any substantial artifacts affecting diagnostic confidence.
Even without dose-reduction regimens,
according to P.
Prakash et al.
a high-definition ASIR protocol has proven superior to standard FBP reconstruction in patients with diffuse lung disease.
- Iterative reconstruction techniques prove highly beneficial in patients requiring recurrent follow-up studies and especially in children,
with recent technical advances (model-based iterative reconstruction: MBIR) showing even higher efficiency,
E.Herin et al.
finding that reduced-dose CT with MBIR reconstruction can decrease radiation dose delivered to patients with lymphoma,
while keeping an image quality similar to that obtained on standard-dose CT.
- Furthermore,
according to P.
Pickhardt et al.
better imaging quality in ultralow-dose CT examinations may be achieved by using more specialized iterative reconstruction methods,
as MBIR.
- ASIR and MBIR have been reported to help also in screening settings,
according to Mathieu KB et al.
who have studied the efficiency of iterative reconstruction protocols in lung cancer screening.
- In neuroradiology,
K.
Kilic et al.
reported that,
even if the effect of ASIR on noise reduction observed in head CT is less than that reported previously in abdomen and chest CT,
iterative reconstruction is useful in cerebral CT scans.
- In urology imaging,
SH Park et al.
have shown the usefulness of low-dose CT with iterative reconstruction in the diagnosis of urinary stones.
- Also in cardiac imaging,
Y Hou et al.
have shown that,
in 256-MDCT coronary angiography,
iterative reconstruction can provide equivalent or improved coronary image quality compared to routine-dose FBP reconstruction,
while enabling radiation dose reductions of 55%.