57 AJTCCM VOL. 29 NO. 2 2023
Background. Clinicians’ interpretation of lung scan reports will determine which further management decisions are taken when potentially
fatal pulmonary embolism (PE) is suspected.
Objectives. To assess current referring clinicians’ interpretation of the terminology used in ventilation/perfusion (V/Q) scan reports,
whether this interpretation is aected by experience level, and how it aects clinical management decisions.
Methods. Th s was a questionnaire-based cross-sectional study. Between September 2020 and May 2021, 300 questionnaires were distributed
among clinicians who refer patients for V/Q scans.
Results. Of the 162 clinicians who responded, 94% thought that there is >85% likelihood of PE or defin tely PE present when a scan is
reported as ‘high probability of PE’; 87% interpreted ‘low probability of PE’ as <10% likelihood of PE or defin tely no PE present. Overall,
>70% of clinicians across all experience levels correctly interpreted the intended meaning of probability categories according to the Modifi d
Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) II criteria. Of the respondents, 77% agreed that clinically signifi ant
PE is ruled out by a normal scan. Further investigation for inconclusive fi dings, features of parenchymal lung disease and cardiomegaly
were selected by 72%, 93% and 98% of clinicians, respectively.
Conclusion. e ndings of this study regarding high-probability scan results were in line with existing literature on lung scan report
interpretation. However, our fi dings regarding low-probability scan results and negative V/Q scan specific ty contrasted with the fi dings in
these articles, suggesting that clinicians are now more familiar with lung scan interpretation guidelines. Experience level did not signifi antly
aect interpretation of reports. Although most clinicians agreed that a negative scan excludes clinically signifi ant PE, two-thirds of them
would still subject the patient to further unnecessary investigations to exclude PE.
Keywords. Pulmonary embolism, clinician’s interpretation, lung scan.
Afr J Thoracic Crit Care Med 2023;29(2):e271. https://doi.org/10.7196/AJTCCM.2023.v29i2.271
Pulmonary embolism (PE) is responsible for 10% of deaths in
hospitalised patients.[1,2] Prompt diagnosis and treatment of PE are
critical, as undiagnosed PE is associated with high rates of morbidity
and mortality.[1-4] Untreated PE results in morbidity from pulmonary
hypertension, recurrent PE and right ventricular failure.[1-4] Conversely,
an inaccurate diagnosis of PE and resultant inappropriate anticoagulation
places a patient at risk of bleeding, thrombocytopenia and drug-induced
hypersensitivity reactions.[1-4] Diagnostic lung imaging may include
computed tomography pulmonary angiography (CTPA) or ventilation/
perfusion (V/Q) scintigraphy. e choice of investigation depends on
several factors, including renal dysfunction, pregnancy, contrast allergy,
radiation exposure, and the clinician’s preference.[2,3,5] An unambiguous
conclusion on a V/Q scan report is essential for correct interpretation
by clinicians and further patient treatment.
The choice of words in an imaging (nuclear medicine (NM)/
radiology) report can inuence the clinician’s interpretation of it.
Clinicians’ interpretation of ventilation/perfusion lung scan re-
ports: Where are we today?
A Ismail,1 MB BCh, FCNP (SA), MMed (Nucl Med) ; M Wong,2 MB BCh, FCP (SA), FCCP, FRCP (Lond);
S Dhoodhat,1 MB BCh, FCNP (SA), MMed (Nucl Med); M D T Vangu,1 MD, FCNP (SA), MMed (Nucl Med), MSc, PhD
1 Department of Nuclear Medicine, Charlotte Maxeke Johannesburg Academic Hospital and Faculty of Health Sciences, University of the
Witwatersrand, Johannesburg, South Africa
2 Division of Pulmonology, Department of Internal Medicine, Chris Hani Baragwanath Hospital and Faculty of Health Sciences, University of the
Witwatersrand, Johannesburg, South Africa
Corresponding author: A Ismail (draismail94@gmail.com)
Study synopsis
What the study adds. Our fi dings regarding a low-probability ventilation/perfusion (V/Q) scan and the specific ty of a negative V/Q scan
contrasted with previous articles on lung scan interpretation, suggesting that clinicians are now more familiar with lung scan interpretation
guidelines.
Implications. Although most clinicians understood the negative predictive value of a V/Q scan, 20% would still investigate further with
computed tomography pulmonary angiography or treat as confi med pulmonary embolism. Education of clinicians about the negative
predictive value of V/Q scans is important to avoid unnecessary radiation or anticoagulation.
ORIGINAL RESEARCH: ARTICLES
58 AJTCCM VOL. 29 NO. 2 2023
Variations in how a statement is worded or the actual words used can
aect further decision-making.[5-9] Articles on V/Q scan interpretation
by Gray etal.[6,7] and Siegel etal.[10] showed that many clinicians have
never fully understood the meaning of PE likelihood probabilities. A
wide variation in the interpretation of probabilities by NM physicians
themselves was also found.[6,7]
e Modifi d Prospective Investigation of Pulmonary Embolism
Diagnosis (PIOPED) II criteria developed in 2008[5,11] have traditionally
been used in our NM department for planar V/Q scan reporting.
According to this system, a high probability of PE scan equates to
>85% likelihood of PE.[5] A very low probability of PE scan translates
to <10% likelihood of PE.[5] e likelihood of PE is reported as a
linguistic probability (high, indeterminate, low or very low probability)
and not numerical percentages.[12] In the event of an abnormal chest
radiograph, a V/Q single-photon emission computed tomography
(SPECT) technique is used. Low-dose computed tomography (CT)
can additionally be acquired for better visualisation of the lung fi lds.
e interpretation criteria for V/Q SPECT include categories of ‘PE
present’, ‘PE absent’ and ‘non-diagnostic for PE’, instead of using
probabilities of PE.[3] Use of the V/Q SPECT technique has become
increasingly popular in the past decade. Planar V/Q imaging has a
sensitivity of 67 - 85% and a specific ty of 78 - 93%.[2] e sensitivity
and specific ty of CT pulmonary angiography are similar, with values
of 78 - 83% and 84 - 96%, respectively.[5,11] V/Q SPECT has improved
the sensitivity and specific ty of V/Q scans to 96 - 99% and 91 - 98%,
respectively,[3,10] even in patients with abnormal chest radiographs and
changes in lung parenchyma. ree-dimensional images have resulted
in fewer inconclusive scans.[2,3]
e greatest utility in the interpretation of lung scans is a normal V/Q
scan, which essentially excludes clinically signifi ant PE, irrespective
of the pre-test probability.[5,7,11] However, Gray etal.[7] found that many
clinicians still misunderstood the specific ty of a normal V/Q scan. ey
reported that only 34% of 217 consultant physicians understood that a
normal lung scan makes a diagnosis of PE highly unlikely. A normal
report was interpreted to still mean an uncertain diagnosis by 31%
of their respondents. Indeterminate V/Q reports are also frequently
misinterpreted by clinicians as excluding PE.[13] Th s misinterpretation
is detrimental to patient care, as previous studies have shown that up
to 30% of patients with indeterminate scans have proven pulmonary
emboli on subsequent gold-standard imaging with angiography.[13]
Our NM department has modifi d the acquisition of lung scans
in certain cases (omitting the ventilation component) because of the
COVID -19 pandemic. e modifi d acquisition of lung scans has
resulted in a shift in our reporting style over the past 2 years. We use
the Perfusion-only Modied PIOPED II system for patients who do
not have a recent (<48 hours) negative COVID test. Perfusion images
are compared with a recent (<24 hours) chest radiograph or a low-
dose CT scan of the chest. Like V/Q SPECT-CT, this system includes
categories of PE present, PE absent and non-diagnostic for PE, instead
of using probabilities of PE.[2,12]
Our NM department is based at two large academic tertiary
hospitals aliated to the University of the Witwatersrand, South
Africa. They serve the city of Johannesburg and surrounding
regions. Approximately 1 500 V/Q studies are performed annually.
Interaction with referring physicians mainly occurs when a V/Q
scan is requested. e discussion focuses on the pre-test probability
of PE. Interaction with the referring clinician aer the scan has
been performed is limited. e NM report is the primary method of
communication with referring physicians. e department therefore
has very little feedback with regard to how referring clinicians
interpret our V/Q scan reports. From anecdotal reports in the
department, very few clinicians have noticed or enquired about the
dierences in reporting systems so far.
Publication of the articles[6,7,10] on lung scan interpretation in
1993 and 2004 took place aer the initial 1983 PIOPED I study.
Since then, criteria for a diagnosis of PE, scanning technology and
technique have changed substantially. Although many articles have
been written on radiology reports in the past three decades, little
has been published on current clinicians’ interpretation of V/Q
scans. e main objective of this study was to assess the referring
clinicians’ interpretation of the terminology used in V/Q scan
reports. In addition, we aimed to assess whether this interpretation
is aected by experience level and how interpretation aects clinical
management decisions.
Methods
A questionnaire-based study was conducted among clinicians who
refer patients to the NM department. Medical students and short-
term visiting doctors were excluded from the sample. Th s was an
observational, cross-sectional study. There were 300 online and
paper-based questionnaires distributed between September 2020 and
May 2021. e questions related to demographic details, including
experience level, understanding of terminology used in reports, and
impact on management decisions (see Appendix A (available online
at https://www.samedical.org/le/2028) and Appendix B (https://
www.samedical.org/le/2029) for the study information sheet and
questionnaire). Respondents worked in the internal medicine, surgery
and obstetrics and gynaecology (O&G) departments. e sample
included interns, medical ocers, registrars (residents/specialists in
training) and specialist consultants.
e questionnaire was first validated in a pilot study. e
Microsoft Forms survey collection tool (version 16.30, Microsoft
365, 2019; Microsoft USA) was used for online questionnaires. Data
analysis was performed using Microsoft Excel (version 16.30) and
Microsoft Word (version 16.30). Descriptive statistics were used.
Categorical variables were presented as frequencies, percentages and
graphs.
Permission was obtained from the University of the
Witwatersrand Human research Medical Ethics Committee prior to
commencement of the study (ref. no. M200320).
Results
Three hundred questionnaires were distributed and 162 completed
responses were received. The majority of the respondents
were registrars, who provided 68 (42%) of the responses overall, 37
responses (23%) were from interns and 33 (20%) were from
consultants, while the smallest number of responses (n=25; 15%)
was received from the category of medical offic .
Years of experience were categorised as 1, 2 - 5, 6 - 10 and >10
years. Of the respondents, 134 (83%) had ≥2 years of working in
clinical medicine. Almost a quarter of the respondents were senior
clinicians with >10 years of experience. The largest number of
responses was received from registrars with 2 - 5 years of
experience.
ORIGINAL RESEARCH: ARTICLES
AJTCCM VOL. 29 NO. 2 2023 59
e majority of the responses (67%) were from the internal medicine
department. Smaller and similar numbers of responses (16-17%)
were received from the O&G and surgery departments.
Clinicians’ interpretation of terminology used in V/Q
scan reports
When asked to interpret the meaning of a scan reported as ‘high
probability of PE’, the majority of clinicians (94%) responded that
there is >85% likelihood of PE or denitely PE present. Overall, 124
clinicians (76%) considered the likelihood of PE to be >85% when the
report mentioned ‘high probability of PE’. Fig.1 shows the proportions
of responses for each category of clinician.
Fig.2 shows that when a scan was reported as ‘low probability of PE’,
most clinicians (n=141; 87%) interpreted this as <10% likelihood of PE
or defin tely no PE present. Overall, 127 clinicians (78%) considered
the likelihood of PE to be <10% when the report stated ‘low probability
of PE’. Only one registrar entered a qualitative response under the
option of ‘other’ and considered a ‘low probability of PE’ to be <5%
likelihood of PE.
Participants were asked what terminology they preferred for V/Q
scan reports. e preferred terminology for 81 clinicians (50%) when
there was no PE present was ‘no convincing evidence of PE’. Th s was
followed by 61 clinicians (38%) who preferred the phrase ‘scan is
negative for PE’. A minority of clinicians preferred the terms ‘normal’
and ‘PE absent’. When PE was present, the preferred terminology for
86 clinicians (53%) was ‘fi dings consistent with PE’, followed by ‘scan
is positive for PE’ for 59 clinicians (36%). e phrases ‘PE present’
and ‘abnormal V/Q scan’ were preferred by a minority. Th s pattern
was consistent in the consultant, registrar, medical office and intern
subcategories.
For a non-diagnostic V/Q report, 111 clinicians (68%) preferred the
term ‘inconclusive’, while 43 (27%) preferred ‘indeterminate’. ere
were 8 clinicians (5%) who preferred the term ‘non-diagnostic’, all of
whom worked in internal medicine.
Approximately two-thirds of the clinicians surveyed preferred the
use of numerical rather than qualitatively described PE probability.
Eect of experience level on interpretation of V/Q scan
reports
Fig.3 shows that ≥80% of clinicians with an experience range of 2 - 5
and 6 - 10 years correctly interpreted the meaning of high probability
of PE according to the Modifi d PIOPED II guidelines. Of clinicians
with 1 or >10 years of experience, <80% had the interpretation correct.
Fig.4 illustrates that of clinicians with an experience range of 6 - 10
years, 88% had the interpretation of low probability of PE correct
according to the guideline. For the rest of the experience categories,
72 - 79% of clinicians correctly interpreted the meaning of low
probability of PE according to the Modifi d PIOPED II guidelines.
Effect of clinicians’ interpretation of the presence
or absence of venous thromboembolism on further
clinical management
Table1 illustrates the course of action the clinicians would take in
response to specic ndings on a V/Q scan report.
Fig.5 shows that the majority of respondents agreed with the statement
that clinically significant PE is ruled out by a normal V/Q scan.
e percentage of respondents for each category was similar, with
26consultants (79%), 54 registrars (81%), 19 medical offic s (76%)
and 26 interns (70%). e total number of clinicians in agreement
was 125 (77%), and the total number not in agreement was 37 (23%).
Of the clinicians, 60% admitted to rarely or never contacting the
NM physician if a report was unclear. e majority of these clinicians
did not offer a specific reason for this. Several junior clinicians
mentioned that they would rely on their supervising registrar to clarify
a report if necessary. A few clinicians also mentioned that it is too time
consuming to contact the relevant person in the NM department. e
remaining 40% of clinicians reported that they had contacted the NM
physician at least once to clarify a report.
Suggestion of further management by NM physicians
Of the respondents, 108 (67%) thought that advice by the NM
physician regarding further management would be useful for all
reports, 51 (31%) thought that it was necessary for inconclusive scans
only, and 3 (2%) did not want further management advice on the
report. Clinicians from all categories, but registrars in particular, did
appreciate further management advice.
100
90
80
70
60
50
40
30
20
10
0
Category of clinician
Respondents, %
Consultant Registrar Medical ocer Intern
<5% likelihood of PE <10% likelihood of PE
<50% likelihood of PE PE unlikely No PE present
70
12
15
3
0.6
84
9
6
80
12
8
76
22
2
Fig.2. Interpretation of V/Q scan reported as low probability for PE.
(V/Q = ventilation/perfusion; PE = pulmonary embolism.)
100
90
80
70
60
50
40
30
20
10
0
Respondents, %
6
Consultant
64
3
27
4
Registrar
84
12
4
Medical ocer
80
16
14
Intern
70
16
Category of clinician
>50% likelihood of PE >85% likelihood of PE
PE likely PE present
Fig.1. Interpretation of V/Q scan reported as high probability for PE.
(V/Q = ventilation/perfusion; PE = pulmonary embolism.)
ORIGINAL RESEARCH: ARTICLES
60 AJTCCM VOL. 29 NO. 2 2023
Discussion
e response rate to the questionnaire was relatively low at 54%.
Similar studies on V/Q scan interpretation[6,7,10] had response rates of
44 - 64%. Data from a review of nine studies[14] comparing online and
paper-based questionnaires have shown the expected response rates
to be 33% and 56%, respectively. Various specialties were therefore
included in the present study in an attempt to increase the number
of participants and ensure that responses were less biased in favour
of those who are familiar with venous thromboembolism guidelines.
The majority of responses were received from registrars. This is
understandable, as they are the primary physicians at the bedside who
review V/Q reports and treat patients accordingly. ey also form the
direct link between junior and senior doctors in academic institutions.
Clinicians’ interpretation of terminology used in V/Q
scan reports
Interpretation was assessed according to understanding and knowledge
of terminology used in the Modifi d PIOPED II criteria. Use of the
specific term ‘PIOPED criteria’ was omitted in the questionnaire, as
many clinicians may not be familiar with this terminology.
Most clinicians correlated numerical likelihoods with phrases
of probability correctly and understood the terms of the Modifi d
PIOPED II criteria as intended. A high-probability scan was
correctly interpreted by 94% of respondents, refl cting the fi ding
by Gray etal.[6] that 97% of clinicians understood the intended
meaning of a high-probability scan. However, they found that
for a low-probability scan, 43% of respondents would still have a
working diagnosis of PE. In contrast, our study found that for a
low-probability scan, only 13% of respondents would still consider a
working diagnosis of PE. Th s was in line with a more recent study by
Siegel etal.,[10] who had similar fi dings in 11% of their respondents.
A reason for this dierence may be that since the time of the article
by Gray etal.,[6] the initial PIOPED criteria for low probability of PE
(20% probability of PE) have been refi ed to increase the specific ty.
Gray etal.[6] found that only a third of consultant physicians
understood that a normal lung scan makes a diagnosis of PE highly
unlikely. A normal report still meant an uncertain diagnosis for
a third of the physicians surveyed. Th s may have been due to the
high negative predictive value of a normal V/Q scan not being well
recognised outside the NM specialty at that time. If the clinician
erroneously still considers the possibility of PE, it will result in
either inappropriate anticoagulation therapy or unnecessary further
investigations. In contrast, in our study, 77% of clinicians (n=125)
agreed that a normal V/Q scan ruled out a clinically signifi ant PE,
and presumably would not use anticoagulation in these patients.
Among consultant physicians, the proportion in agreement was
79%. Th s fi ding suggests that the high negative predictive value of
a negative result for a V/Q scan is better appreciated today than at the
time of publication of the previous articles.
Eect of experience level on interpretation of V/Q scan
reports
Familiarity with PE investigation guidelines and commonly used
phrases in reports is likely to differ depending on the frequency
with which PE is encountered. When answers matching Modifi d
PIOPEDII groups correctly were broken down into each experience
category, registrars and medical officers scored the highest. This
is reassuring, as they are expected to make decisions regarding
100
90
80
70
60
50
40
30
20
10
0
Years of experience
Respondents, %
>10 6 - 10 2 - 5 1
>50% likelihood of PE >85% likelihood of PE
PE likely PE present
5
68
3
24
3
82
15
9
80
11
10
73
17
Fig.3. Interpretation of V/Q scan reported as high probability for PE,
by experience in years. (V/Q = ventilation/perfusion; PE = pulmonary
embolism.)
100
90
80
70
60
50
40
30
20
10
0
Years of experience
Respondents, %
>10 6 - 10 2 - 5 1
79
5
13
388
8
4
2
72
17
9
77
23
<5% likelihood of PE <10% likelihood of PE
<50% likelihood of PE PE unlikely No PE present
Fig.4. Interpretation of V/Q scan reported as low probability for PE,
by experience in years. (V/Q = ventilation/perfusion; PE = pulmonary
embolism.)
90
80
70
60
50
40
30
20
10
0
Category of clinician
Respondents, %
Consultant Registrar Medical ocer Intern
Agree Disagree
79
21
81
19
76
24
70
30
Fig.5. Normal V/Q scan rules out PE. (V/Q = ventilation/perfusion; PE
= pulmonary embolism.)
ORIGINAL RESEARCH: ARTICLES
AJTCCM VOL. 29 NO. 2 2023 61
anticoagulation and should be aware of the latest guidelines. e
consultant (specialists) group scored the lowest for answering these
questions correctly. Th s group was more likely than other groups to
prefer the clearly stated options of ‘PE present’ or ‘PE absent’ instead
of another likelihood option. Th s is in keeping with studies suggesting
that experience level gives insight and confide ce to commit to or rule
out a diagnosis.[9,15] Compared with the other groups, a slightly lower
proportion of the intern group correctly interpreted the Modifi d
PIOPED guidelines. e Royal College of Radiologists 2018 guidelines
for reporting imaging investigations[16] recommend that the report
should be appropriate for the referrer. ey suggest that the wording
of a report should dier when written to a general practitioner as
opposed to a specialist in a particular fi ld. It is not always possible
to do this in a hospital setting, but a clear report that is universally
understood is achievable. Input from the referring clinician as the end
user is important for guiding imaging physicians with regard to what
clinicians want to see in reports.
Preferred terminology
e present study showed that only 4 - 9% of respondents preferred
the conclusion of ‘PE absent’ or ‘PE present’, yet this is the terminology
used in the guidelines for the Perfusion-only Modifi d PIOPED II
system and V/Q SPECT-CT. All responses in our study were collected
aer the COVID -19 pandemic began, and our reporting style had
changed in relevant cases. Radiology guidelines rarely consider
preferences for reporting expressed by clinicians, and this may lead
to confusion.[8,17] e terms ‘absent’ and ‘present’ are straightforward
to understand, and it is likely that clinicians prefer the other terms
because of linguistic preference rather than clarity of meaning.
Clinicians may also prefer probabilities or direct descriptions of ‘scan
is negative for PE’ or ‘scan is positive for PE’, as this is the reporting
system that they have become accustomed to. While it is important to
consider the clinicians’ preferences, as they are the end users, it is also
important to follow guidelines and standardise the use of terminology
to avoid confusion.
e preference for terminology such as ‘no convincing evidence
of PE’ and ‘ndings consistent with PE’ found in the present study
is in contrast to Hartung etal.,[15] who suggest minimal use of terms
of perception and avoiding redundancy. ey are of the opinion that
words such as ‘is visualised’ or ‘there is evidence of ’ may be omitted
without a change in meaning of the report.
For a non-diagnostic V/Q report, two-thirds of our respondents
preferred the term ‘inconclusive’. Only 5% of clinicians preferred the
term ‘non-diagnostic’, which is used in the guidelines. ese clinicians
all worked in internal medicine and most were consultants. Th s
fi ding suggests that preference for the term ‘non-diagnostic’ was not
simply a random language preference but rather due to familiarity
with the guidelines and terminology. No other specialties chose this
unusual option. Unlike the words ‘absent’ and ‘present’, the term ‘non-
diagnostic’ is not common language. In non-diagnostic cases, the use
of an easily understood alternative term (such as ‘inconclusive’) may
avoid confusion. Approximately two-thirds of clinicians would prefer
the use of numerical instead of qualitatively described PE probability.
ese fi dings are in line with the literature, which advocates the use
of numerical expression instead of technical language when describing
the likelihood of PE to reduce confusion among clinicians.[9,10,14,16,18]
Effect of clinicians’ interpretation of the presence
or absence of venous thromboembolism on further
clinical management decisions
At our hospitals, CTPA is usually the investigation of choice when
investigating PE. V/Q scans are usually requested in the presence
Table1. Clinical decisions in response to specic findi gs on a V/Q scan report
Total, N (%) Consultant, n (%) Registrar, n (%) Medical ocer, n (%) Intern, n (%)
Inconclusive V/Q scan
Book CTPA if no contraindications 116 (72) 27 (82) 42 (63) 16 (64) 31 (84)
erapeutic anticoagulation and
repeat V/Q scan in 7 - 14 days
19 (12) 2 (6) 10 (15) 5 (20) 2 (5)
Use my clinical judgement and
treatas PE
27 (16) 4 (12) 15 (22) 4 (16) 4 (11)
Features of parenchymal lung disease
Treat as pneumonia 8 (5) 0 6 (9) 2 (8) 0
Investigate further 151 (93) 33 (100) 60 (90) 23 (92) 35 (95)
Ignore the comment 3 (2) 0 1 (1) 0 2 (5)
Cardiac outline enlarged
Confi m cardiomegaly on CXR 72 (44) 13 (39) 30 (45) 14 (56) 15 (41)
Refer for cardiac review 88 (54) 19 (58) 36 (54) 11 (44) 22 (59)
Ignore the comment 2 (2) 1 (3) 1 (1) 0 0
High clinical suspicion for PE but
scanis negative for PE
Book CTPA if no contraindications 95 (59) 27 (82) 32 (48) 13 (52) 23 (62)
Consider another diagnosis 54 (33) 4 (12) 32 (48) 9 (36) 9 (24)
Trust my clinical judgement and
treat as PE
13 (8) 2 (6) 3 (4) 3 (12) 5 (14)
V/Q = ventilation/perfusion; CTPA = computed tomography pulmonary angiography; PE = pulmonary embolism; CXR = chest radiograph.
ORIGINAL RESEARCH: ARTICLE
62 AJTCCM VOL. 29 NO. 2 2023
of contraindications to the use of contrast material, including renal
dysfunction and allergy. V/Q scans are also predominantly used by
the O&G department for pregnant patients in an attempt to decrease
radiation exposure to the maternal breast tissue and fetus. ere has
been increased utilisation of V/Q scans for the investigation of chronic
PE. An overloaded radiology department sometimes makes it more
reasonable to choose a V/Q scan over CTPA, as an emergency scan
may be obtained much sooner.
Inconclusive fi dings on a V/Q scan would lead the majority of
the respondents (72%) to investigate further with CTPA, if there
were no contraindications. However, if CTPA is contraindicated,
another strategy needs to be employed. Very few respondents
(12%) selected the option of treating with therapeutic doses of
anticoagulation and repeating the perfusion-only scan in 7 - 14
days to assess for resolution of defects. is nding implies that
clinicians are unaware of this option, which does not follow any
specific guideline. Resolution of defects on subsequent V/Q imaging
will indicate that brinolysis has occurred and a diagnosis of PE is
likely. Th s is an option for further imaging that may be useful when
CTPA is contraindicated.[3] If CTPA is not absolutely contraindicated
and the concern is more for avoiding radiation exposure (e.g. if the
patient is a young woman with radiosensitive breast tissue), this
approach may also be suitable.
e phrases ‘features of parenchymal lung disease’ and ‘cardiac outline
is enlarged’ in the scan report would lead to further investigation and
consideration of other diagnoses apart from PE by most respondents
(93% and 98%, respectively). Th s is in agreement with Lukaszewicz
etal.,[9] who found that nearly all physicians felt obliged to further
investigate abnormal fi dings mentioned in the report.
In the present study, most clinicians (77%) agreed that a normal
V/Q scan ruled out a clinically signifi ant PE. However, when asked
about clinical management in response to a negative V/Q scan in the
context of high clinical pre-test probability, only a third of clinicians
would consider an alternative diagnosis. A signifi ant proportion
of clinicians (59%) would still investigate further with CTPA. Th s
discrepancy is confusing to interpret, as we would expect 77% of
clinicians to consider an alternative diagnosis once they had ruled out
PE, and it suggests that many clinicians either do not trust or do not
fully understand the negative predictive value of a V/Q scan. Clinicians
may also be concerned about false-negative results. Dismissal of the
negative predictive value of a V/Q scan potentially exposes the patient
to unnecessary further radiation and anticoagulation. Education of
clinicians about the negative predictive value of V/Q scans is therefore
important. An effici t way to reach all clinicians reading the report
may be to include a statement at the end of the report explaining the
implication of a negative V/Q scan.
Two-thirds of our referring clinicians admitted to rarely or never
contacting the NM physician if a report was unclear. Th s is concerning,
as the NM department’s location and telephone number together with
the surnames of the reporting physicians (registrar and consultant)
are clearly stated on all our reports. Th s fi ding highlights a need for
the NM department to engage further with clinical departments to
determine the reasons behind the lack of contact.
We found that most clinicians from all experience categories
were in favour of receiving some advice on further management
related to scan ndings, which is similar to responses reported by
others.[9,13] Lukazewicz etal.[9] found that a majority of physicians
wantedspecific recommendations on further imaging and follow-up
and would appreciate a time frame. ey also emphasised that the
way in which recommendations are phrased determines whether the
clinician follows them. ey found that most clinicians would follow
recommendations if they were stated outright. However, if terms
such as ‘if clinically indicated’ were used, less than half of clinicians
felt obliged to followthem.
Study limitations
A limitation of the present study is that the participants were clinicians
from the two academic hospitals where the NM department is based.
Clinicians from primary-, secondary- or other tertiary-level hospitals
(not aliated to the University of the Witwatersrand) were excluded,
and this could have resulted in selection bias. e study f i dings
may not be generalisable to all clinicians. Another limitation of the
study was the low response rate of 54%. A future study including
assessment of clinicians from academic-aliated and non-aliated
hospitals throughout the country would be important to fully achieve
the objectives of this study and increase the response rate. Expanding
this study to include several countries would make the fi dings truly
universal and unique.
e reasons for the preference for certain terminology by clinicians
were not explored in the questionnaire used for this study. A qualitative
future study exploring these reasons in detail would enable more
defin te conclusions.
Conclusion
This study found that the majority (77 - 78%) of respondents
understood the Modifi d PIOPED and V/Q SPECT-CT interpretation
guidelines as intended. We found that experience level did not
signifi antly aect interpretation of reports. Clinicians’ interpretation
of the presence or absence of venous thromboembolism would result
in further investigation by a majority of clinicians for scans with
inconclusive findings, features of parenchymal lung disease and
cardiomegaly. Although most clinicians agreed that a negative V/Q
scan excludes clinically significant PE, not all of these clinicians
would consider an alternative diagnosis.
The findings of this study regarding high-probability scan results
were in line with the findings on lung scan interpretation reported
by Gray etal.[6,7] However, our findings regarding low-probability
scan results and negative V/Q scan specificity contrasted with the
findings in these articles, suggesting that clinicians are now more
familiar with lung scan interpretation guidelines and the
implications of findings in V/Q scan reports.
This study will help us to improve our reporting style to deliver
reports with maximal clinical utility to our referring clinicians. It will
assist in improving the management of a serious condition that oen
has an evasive diagnosis.
Declaration. MW is a member of the editorial board.
Acknowledgements. None.
Author contributions. AI: study conception and design, data acquisition,
analysis and interpretation, draing and editing of the manuscript, critical
revision of important scientific content. MW: study conception and
ORIGINAL RESEARCH: ARTICLES
AJTCCM VOL. 29 NO. 2 2023 63
interpretation of data, critical revision of important scientific content.
SD: study design and interpretation of data, critical revision of important
scientific content. MDTV: interpretation of data, critical revision of
important scientific content. All authors approved the fi al manuscript
for submission.
Funding. None.
Confl cts of interest. None.
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Submitted 12 August 2022. Accepted 2 May 2023. Published July 2023.
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