British Journal of Radiology (2004) 77, 445-448
© 2004 British Institute of Radiology
doi: 10.1259/bjr/80737867
Small pulmonary arteriovenous fistulae revealed by scintigraphy during selective injection of 99Tcm-macroaggregated albumin
T Hirota, MD
T Yamagami, MD, PhD
T Nakamura, MD, PhD
C Okuyama, MD
Y Ushijima, MD, PhD
and
T Nishimura, MD, PhD
Department of Radiology, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo, Kyoto, 602-8566, Japan
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Abstract
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We report a case of small pulmonary arteriovenous fistulae precisely diagnosed by a combination of selective pulmonary arteriography and scintigraphy during 99Tcm-macroaggregated albumin injection via the peripheral pulmonary artery.
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Introduction
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Pulmonary arteriovenous fistulae (PAVFs) are rare congenital vascular anomalies, existing between the pulmonary arteries and pulmonary veins, which form right-to-left shunts. In one third of patients lesions are multiple [1]. In general, these vascular anomalies are easily diagnosed radiologically by chest radiograph, chest CT and pulmonary perfusion scintigraphy. However, it is sometimes difficult to confirm the correct location of PAVFs [2]. We report on a case in which the existence and correct location of very subtle PAVFs were clarified by the combined use of selective pulmonary arteriography and scintigraphy during 99Tcm-macroaggregated albumin (MAA) injection via the peripheral pulmonary artery.
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Case report
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A 25-year-old woman was referred with asymptomatic hypoxaemia that was incidentally detected by ophthalmologists during surgery for vitreal haemorrhage under local anaesthesia. Her family history was non-contributory. She had a history of aplastic anaemia and dyskeratosis congenita. There was no history of liver damage. Physical examination demonstrated anaemia at the palpebral conjunctiva, reticulate skin hyperpigmentation of the neck, chest, back, medial side of the femur and around the orbit. Laboratory data demonstrated pancytopenia probably caused by aplastic anaemia and hypoxaemia with an oxygen saturation of 80%, an arterial oxygen blood pressure of 40 mmHg, and an arterial blood pressure of carbon dioxide of 34 mmHg.
Although chest radiograph and chest CT were normal, the existence of PAVFs was suspected from the above clinical data. We performed 99Tcm-MAA whole body imaging, which revealed radioactive accumulation in the lungs, kidneys, brain, thyroid and spleen. These findings were consistent with the presence of a right-to-left shunt (Figure 1
). Pulmonary arteriography showed abnormal vessels at the medial site of the left descending branch (Figure 2). However, because these abnormal vessels were very subtle and did not demonstrate thin-walled aneurysmal bulbous sites, which are one of the characteristic features of PAVFs, and the feeding artery and draining vein were unclear, we could not confirm that the abnormal vessels were PAVFs. We therefore performed selective pulmonary arteriography and scintigraphy during 99Tcm-MAA injections via the abnormal vessels to confirm that these were PAVFs.
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Figure 1. 99Tcm-macroaggregated albumin posterior imaging showed radioactive accumulation in the kidneys (arrows) and spleen (arrowheads).
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Figure 2. Pulmonary arteriography showed abnormal vessels at the medial site of the left descending branch (arrow).
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A 5 French catheter was inserted via the right jugular vein to the pulmonary arterial trunk, and a 3 French microcatheter (Cordis; MASS TRANSIT, Miami Lakes, FL) was coaxially advanced into the left superior lower arterial branch (A6 branch); one of the left lower branches of which was suspected to have a PAVF according to the previous pulmonary arteriography. 10 ml of 300 mgI ml–1 iopamidol (Iopamiron; Schering, Berlin, Germany) was manually injected via the microcatheter, which was selectively advanced into the terminal end of the left A6 branch. The findings of selective pulmonary arteriography revealed subtle abnormal vessels, running from inside to outside after contrast medium filled the arterial branch, but prompt venous return through the PAVFs was unclear (Figure 3). Because it was difficult to diagnose the abnormal vessels as PAVFs by selective pulmonary arteriography alone, an attempt was made to diagnose these vessels using radiopharmaceuticals. The patient was moved to the nuclear medicine division with the microcatheter remaining in the left A6 branch, then scans were started immediately after injecting 70 MBq 99Tcm-MAA via the microcatheter while the patient remained on the gamma camera. The findings of the dynamic image after 99Tcm-MAA injection were as follows: first, the left A6 branch was visualized, then, the pulmonary vein and left ventricle were visualized. Finally, the descending aorta, spleen and kidneys were visualized (Figure 4). This confirmed that the abnormal vessels visualized during selective arteriography of left A6 branch were PAVFs. Because the patient was asymptomatic in her daily life and the PAVFs were small, a decision was made to observe without therapeutic intervention.
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Figure 3. Selective pulmonary arteriography via the left A6 branch showed abnormal subtle vessels (arrows) after contrast medium filled the arterial branch, but prompt venous return through pulmonary arteriovenous fistulae remained unclear.
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Figure 4. (a) Anterior and (b) left lateral views of dynamic images (five frames, every 2 s) obtained immediately after the injection of 99Tcm-macroaggregated albumin via the left A6. Schema of the images is also shown. The left S6 pulmonary parenchyma was initially visualized (arrow heads), followed by the left ventricle (thick arrows). Note that the infused 99Tcm-macroaggregated albumin is visible within the microcatheter in the first frame (thin arrow); in the later phases, the compound is visible in the descending aorta, spleen and kidneys.
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3 months later, the patient re-presented with oesophageal cancer with lung, liver, adrenal gland, kidney and bone metastases. Despite chemotherapy, the patient died 6 months after diagnosis of oesophageal cancer. The autopsy findings revealed small PAVFs originating from the left A6 branch of the pulmonary artery and showing a rapid shift from the arterial wall to the venous wall. In other organs, there were no anomalous arteriovenous shunts observed. Although an autopsy was performed, the discrepancy between the imaging findings and blood data can not be well explained.
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Discussion
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Most patients with PAVFs have symptoms such as cyanosis, clubbed digits, and hypercythemia, but recently the number of reports of asymptomatic PAVFs has increased due to the widespread use of chest radiograph or CT images. Muri et al [3] reported that in 50 cases of untreated PAVFs, 7 patients died of ruptured fistulae, 5 patients died of brain abscess, and severe complications including death occurred in 20% of cases. Thus, James et al [4] insisted on the necessity of treatment even for asymptomatic PAVFs. The recent trend in management of such asymptomatic PAVFs is that in cases with feeding arteries more than 3 mm in diameter, treatment is considered necessary [5]. Previously, surgical resection of the shunt was the only available method of treatment [6]. There is no doubt that PAVFs themselves were well-treated by the surgical method, but some damage to the normal lung parenchyma could not be avoided and mortality rates up to 5% were reported [7]. In recent years, less invasive treatments using interventional techniques such as transcatheter embolisation have been widely performed in parallel with the rapid development of various interventional instruments such as microcatheters, imaging modalities, and embolic agents [6, 8, 9].
It is reported that some of the PAVFs occur in association with hereditary haemorrhagic telangiectasia, liver cirrhosis, and so on. Our patient suffered dyskeratosis congenita, which was first described by Zinnser in 1903 [10], followed by Engmann in 1926 [11] and by Cole in 1933 [12]. The disease is sometimes referred to as the Zinnser-Engmann-Cole syndrome. It is a rare hereditary condition of ectodermal dysplasia, which is characterized by dystrophic nails, leukoplakia and reticulate skin hyperpigmentation appearing in the majority of cases at the side of the neck, the chest and around the armpits. There have been approximately 200 cases reported [13]. Progressive bone marrow aplasia and malignancy are the most serious complications. Although respiratory disease in dyskeratosis congenita has also been mentioned in the literature, most cases were interstitial pneumonia [14, 15]. Regarding PAVFs in dyskeratosis congenita, only one case has been reported by Sands et al [16] before the present report.
PAVFs are mainly diagnosed by chest radiograph, chest CT and pulmonary arteriography. Round or oval well-defined nodular lesions and their feeding artery and draining vein can be described as a characteristic finding of PAVFs. 99Tcm-MAA whole body imaging is well-known as an imaging modality to diagnose and to evaluate PAVFs [17]. The appearance of the radiotracer in the systemic circulation to document the brain, kidneys, and spleen after intravenous administration of 99Tcm-MAA particles indicates the existence of the right-to-left shunt running through PAVFs.
There are two morphologic types of PAVFs; the simple and complex types [18]. 79% of PAVFs consisted of the simple type characterized by a single feeding artery draining into a bulbous, non-septated aneurysmal communication with a single draining vein. The remaining 21% of PAVFs have been reported to be the complex type, consisting of two or more pulmonary arterial branches communicating with a bulbous septated aneurysmal part with more than two draining veins. Most PAVFs are easily diagnosed by characteristic features such as thin-walled aneurysmal bulbous sites. However, in the present case, it was difficult to determine the existence of PAVFs by common imaging modalities such as chest radiograph, CT and pulmonary arteriography alone, because the appearance of the abnormal vessels was very subtle and there were no definite thin-walled aneurysmal bulbous sites. Only a few cases of PAVFs have been reported not to be visualized on imaging modalities commonly used to diagnose PAVFs [19, 20]. In those cases, the final diagnosis was obtained by invasive surgical procedures. However, we could prove the existence and precise location of even such non-typical and very subtle PAVFs that were not confirmed by common imaging modalities by utilizing selective pulmonary arteriography and scintigraphy during 99Tcm-MAA injections via the peripheral pulmonary artery. These PAVFs were revealed well by selective injection with only 70 MBq of 99Tcm-MAA, while the standard dose of 99Tcm-MAA particles intravenously administered for the whole body imaging to evaluate PAVFs is 400 MBq in our institution, because it was not necessary to evaluate the existence of PAVFs in all lung segments in the present case. This article may be the first reported use of this technique in the literature.
Received for publication December 23, 2002.
Revision received July 2, 2003.
Accepted for publication August 29, 2003.
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Abstract
Introduction
