Thesis (MScMedSC (Medical Imaging and Clinical Oncology. Nuclear Medicine))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Single photon emission computed tomography (SPECT) with a superior contrast
resolution has been shown to be more sensitive and specific with a lower nondiagnostic
rate than planar imaging in many nuclear medicine studies but it is still not
being routinely implemented in V/Q studies at many centres including Tygerberg
Hospital. There are many studies on V/Q SPECT using Technegas as a ventilation
agent but very limited studies available on 81m Kr gas.
Aim: To clinically compare conventional planar and SPECT V/Q imaging using 81mKr
gas in the diagnosis of pulmonary embolism, with CTPA as the gold standard.
Patients and Methods: All patients referred with clinical suspicion of pulmonary
embolism were assessed. The inclusion criteria were normal chest radiograph,
normal renal function and no contrast allergy. Exclusion criteria were age below 18
years old, pregnancy, abnormal chest radiograph, abnormal serum creatinine/urea
levels and unstable patients. A Well’s score was assigned to each enrolled patient.
Perfusion scintigraphy was performed after intravenous injection 125 MBq of 99mTc
MAA. Ventilation scintigraphy was performed with 81mKr gas. On a dual head
camera, SPECT was done before planar acquisition, while perfusion was done
before ventilation imaging in the same position. Planar V/Q images consisted of 6
standard views. All V/Q SPECT images were reconstructed using ordered-subset
expectation-maximization (OSEM) algorithm and a post-reconstruction 3D
Butterworth filters were applied. V/Q Planar and V/Q SPECT images were later
evaluated and reviewed separately and reported based on recent EANM guidelines
blinded to the CTPA results.
All patients underwent multi-slice CTPA examinations on a 40-detector row scanner.
The images were later assessed and reported blinded to the V/Q results.
Statistical analysis was done using the Fisher exact test for comparison of
categorical variables and the one-way ANOVA for continuous variables (p<0.05 was significant). Results: A total of 104 consecutive patients were referred with clinical suspicion of
pulmonary embolism. Seventy-nine patients were excluded from this study mostly
due to abnormal serum creatinine/urea levels. Only 25 patients were included in this
study, with a mean age of 48 ± 19 years, and 64% being females. When compared
to CTPA as gold standard, the prevalence of PE was 16% [5% – 37% at 95% CI],
sensitivity 75% [21% – 99% at 95% CI], specificity 90% [68% – 98% at 95% CI],
positive predictive value 60% [17% – 93% at 95% CI], negative predictive value 95%
[73% – 100% at 95% CI] and diagnostic accuracy 88% [69% – 97%at 95% CI] for
both V/Q Planar and SPECT. V/Q Planar showed a lower reader confidence i.e.
could only clearly resolve 72% of cases compared to V/Q SPECT, which could
precisely interpret all cases, showed more and better delineated mismatch vs match
and segmental vs non-segmental defects. All patients who were scored as PE
unlikely on Wells’ score (4) had PE ruled out on CTPA (p=0.04581) as well as 89%
of patients on V/Q SPECT and V/Q Planar.
Conclusion: Based on this study, V/Q Planar and V/Q SPECT have a similar
diagnostic performance in patients with a normal or near normal chest X-rays. / AFRIKAANSE OPSOMMING: Enkelfoton emissie rekenaartomografie (EFERT) met beter kontrasresolusie is
bewys om meer sensitief en spesifiek met ‘n laer nie-diagnostiese opbrengs as
planare beelding in verskeie kerngeneeskunde ondersoeke te wees. In Tygerberg
Hospitaal, soos in verskeie ander sentra, word dit egter steeds nie roetineweg vir
ventilasie-perfusiestudies (V/Q) geïmplementeer nie. Daar is verskeie EFERT V/Q
studies met Technegas as ventilasie agens, maar beperkte studies met 81m Kr gas
beskikbaar.
Doel: Om konvensionele planare en EFERT V/Q beelding vir die diagnose van
pulmonale embolisme met mekaar te vergelyk, met rekenaartomografie pulmonale
angiografie (RTPA) as goue standaard.
Pasiënte en Metodes: Alle pasiënte wat met ‘n kliniese vermoede van pulmonale
embolisme verwys is, is geevalueer. Die insluitingskriteria was ’n normale borskas Xstraal,
normale nierfunksie en geen kontrasallergie nie. Uitsluitingskriteria was
pasiënte jonger as 18 jaar, swanger pasiënte, abnormale borskas X-straal,
abnormale serum kreatinien / ureumvlakke en onstabiele pasiënte. ’n Wells telling is
vir elke pasiënt wat in die studie ingesluit is, bepaal.
Perfusiebeelding is uitgevoer na die intraveneuse toediening van 125 MBq 99mTc
MAA. Ventilasiestudies is gedoen met 81mKr gas. Die V/Q EFERT studies is voor die
planare beelding met ’n dubbelkop gammakamera uitgevoer. Perfusiebeelding is
voor die ventilasie in dieselfde posisie verkry. V/Q planare beelding het bestaan uit 6
standaard beelde. Alle V/Q EFERT is met “ordered-subset expectationmaximization”
(OSEM) algoritmes verwerk, en post-rekonstruksie 3D Butterworth
filters is toegepas. V/Q planare en V/Q EFERT beelding is later afsonderlik en
sonder RTPA inligting volgens onlangse EANM riglyne evalueer en gerapporteer.
‘n Veelsnit RTPA met ‘n 40 snit skandeerder is op alle pasiënte uitgevoer. Die
beelde is later beoordeel en gerapporteer sonder inagneming van die V/Q
beeldingsresultate
Statistiese verwerking is gedoen met die Fisher presisietoets vir vergelyking van
kategoriese veranderlikes en die eenrigting ANOVA vir kontinue veranderlikes
(p<0.05 is statisties betekenisvol). Resultate: ‘n Totaal van 104 opeenvolgende pasiënte met ‘n kliniese vermoede van
pulmonale embolisme is verwys. Nege-en-sewentig pasiënte is uitgesluit, in die
meeste gevalle as gevolg van abnormale serum kreatinienvlakke. Slegs 25 pasiënte
is ingesluit, met ’n gemiddelde ouderdom van 48 ± 19 jaar, en 64% vroue. In
vergelyking met RTPA as goudstandaard, was die prevalensie van PE 16% [5% –
37% met 95% VI], sensitiwiteit 75% [21% – 99% met 95% VI], spesifisiteit 90% [68%
– 98% met 95% VI], positiewe voorspellingswaarde 60% [17% – 93% met 95% VI],
negatiewe voorspellingswaarde 95% [73% – 100% met 95% VI] en diagnostiese
akkuraatheid van 88% [69% – 97% met 95% VI] vir beide planare en EFERT V/Q
beelde. V/Q planare beelde het ‘n laer lesersvertroue getoon, nl. dat slegs 72% van
gevalle opgelos kon word relatief tot V/Q EFERT beelde, wat in alle gevalle presies
geïnterpreteer kon word, met meer en beter omskrewe nie-ooreenstemmende
teenoor ooreenstemmende en segmentele teenoor nie-segmentele defekte. In alle
pasiënte met ‘n Wells puntetelling van 4 is PE met die RTPA uitgeskakel
(p=0.04581), terwyl dit in 89% van pasiënte met V/Q EFERT en planare beelde
uitgeskakel is.
Gevolgtrekking: Gebaseer op hierdie studie het V/Q planare en EFERT beelding ‘n
ooreenstemmende diagnostiese prestasie in pasiënte met ’n normale of naby
normale borskas X-straal.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/4358 |
| Date | 03 1900 |
| Creators | Ngoya, Patrick Sitati |
| Contributors | Korowlay, Nisaar A., University of Stellenbosch. Faculty of Health Sciences. Dept. of Medical Imaging and Clinical Oncology. Nuclear Medicine. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 152 p. : ill. |
| Rights | University of Stellenbosch |
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