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PEDIATRIC
UROLOGY
Importance
of methodology on (99m)technetium dimercapto-succinic acid scintigraphic
image quality: imaging pilot study for RIVUR (Randomized Intervention
for Children With Vesicoureteral Reflux) multicenter investigation
Ziessman HA, Majd M
Division of Nuclear Medicine, Russell H. Morgan Department of Radiology
and Radiological Sciences, The Johns Hopkins University, Baltimore, Maryland,
USA
J Urol. 2009; 182: 272-9
- Purpose:
We reviewed our experience with (99m)technetium dimercapto-succinic
acid scintigraphy obtained during an imaging pilot study for a multicenter
investigation (Randomized Intervention for Children With Vesicoureteral
Reflux) of the effectiveness of daily antimicrobial prophylaxis for
preventing recurrent urinary tract infection and renal scarring. We
analyzed imaging methodology and its relation to diagnostic image quality.
- Materials
and Methods: (99m)Technetium dimercapto-succinic acid imaging
guidelines were provided to participating sites. High-resolution planar
imaging with parallel hole or pinhole collimation was required. Two
core reviewers evaluated all submitted images. Analysis included appropriate
views, presence or lack of patient motion, adequate magnification, sufficient
counts and diagnostic image quality. Inter-reader agreement was evaluated.
- Results:
We evaluated 70, (99m)technetium dimercapto-succinic acid studies from
14 institutions. Variability was noted in methodology and image quality.
Correlation (r value) between dose administered and patient age was
0.780. For parallel hole collimator imaging good correlation was noted
between activity administered and counts (r = 0.800). For pinhole imaging
the correlation was poor (r = 0.110). A total of 10 studies (17%) were
rejected for quality issues of motion, kidney overlap, inadequate magnification,
inadequate counts and poor quality images. The submitting institution
was informed and provided with recommendations for improving quality,
and resubmission of another study was required. Only 4 studies (6%)
were judged differently by the 2 reviewers, and the differences were
minor.
- Conclusions:
Methodology and image quality for (99m)technetium dimercapto-succinic
acid scintigraphy varied more than expected between institutions. The
most common reason for poor image quality was inadequate count acquisition
with insufficient attention to the tradeoff between administered dose,
length of image acquisition, start time of imaging and resulting image
quality. Inter-observer core reader agreement was high. The pilot study
ensured good diagnostic quality standardized images for the Randomized
Intervention for Children With Vesicoureteral Reflux investigation.
- Editorial
Comment
A pilot study of the Randomized Intervention for Children With Vesicoureteral
Reflux participating institutions submitting DMSA scans was undertaken
to evaluate quality. Written technique guidelines were given and the
images were submitted to the two authors for review of image quality.
The pilot study lasted for six months. Seventy studies were submitted,
10 of which were resubmissions because of unacceptable quality in the
past. Fourteen institutions submitted cases. The studies compared radiopharmaceutical
dose, time of imaging, overlap of kidney images and adequate counts
in the region of interest with an overall quality evaluation by the
referee nuclear medicine physicians. Sixty studies eventually went through
the complete process and 10 of these were rejected for quality issues
(17%). Sixteen of the studies had disagreement between the two nuclear
medicine experts, most with minor discrepancies such as left right inversions,
however one study was thought to be adequate by one and poor quality
by another.
When details of routine clinical imaging studies are scrutinized in
this fashion it makes one wonder about the clinical judgments that are
made and the quality of imaging at one’s own institution. These
14 institutions were chosen because of their interest and abilities
and still significant problems in following a written protocol, monitoring
of the study while the patient is in the imaging department and processing
the study were discovered. In short, there is still plenty of room for
error.
Of the 70 patients studied in reality there should be 80, since 10 of
them are resubmissions, which should make the statistics 14% worse.
It should be noted in nuclear medicine that there has been a great effort
in trying to standardize kidney imaging and yet it is still an ongoing
process that has not filtered down to each and every institution.
The authors should be commended for publishing not only positive, but
their negative results and letting clinicians recognize that a good
deal of clinical judgment should be used in interpreting and relying
upon imaging studies.
Dr.
Brent W. Snow
Division of Urology
University of Utah Health Sci Ctr
Salt Lake City, Utah, USA
E-mail: brent.snow@hsc.utah.edu |