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Inferior vena cava thrombosis with hot quadrate lobe sign demonstrated by Tc-99m macroaggregated albumin radionuclide venogram and single-photon emission computed tomography/computed tomography
Address for correspondence: Dr. Daris Theerakulpisut, Department of Radiology, Division of Nuclear Medicine, Faculty of Medicine, Khon Kaen University, 123 Mittraphap Highway, Muang District, Khon Kaen 40002, Thailand. E-mail: daris.th@gmail.com
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Abstract
In this article, a case of a young woman who presented with extensive deep venous thrombosis of the inferior vena cava and lower extremities with pulmonary embolism is described. Findings of various imaging modalities highlighting an interesting finding of a “hot quadrate lobe” sign demonstrated by planar radionuclide venography and single photon emission computed tomography/computed tomography are illustrated.
Keywords
Hot quadrate lobe
inferior vena cava obstruction
radionuclide imaging
single photon emission computed tomography/computed tomography
venous thromboembolism
INTRODUCTION
Although now largely supplanted by color Doppler ultrasonography for the diagnosis of deep venous thrombosis of the limbs, radionuclide venography (RNV) has also been shown to have very good diagnostic performance in the detection of lower limb deep venous thrombosis with sensitivity exceeding 80-90%[12] and accuracy of up to 95 to 100% compared with contrast venography.[34] It also imparts a smaller radiation dose than fluoroscopic contrast venography or computed tomography (CT) venography[5] and without the risk of adverse events from radiographic contrast media. Another strong point is that RNV can be done as a part of a ventilation-perfusion lung scintigraphy (V/Q scan) to offer an all-in-one test to assess venous thromboembolic (VTE) disease in the limbs and the lungs in one study.[6] Because deep venous thrombosis and pulmonary embolism can frequently be found concomitantly,[78910] it is the practice in our center to perform a RNV in conjunction with V/Q scanning.
CASE REPORT
A 21-year-old young woman presented with a chief complaint of swelling of bilateral lower extremities, more on the left side than the right, for 2 days prior to seeking medical attention. One month before, she described a similar swelling of her right lower extremity that lasted for about 1 week which spontaneously improved. She has one child of 4 years of age and has been taking oral contraceptive pills for 2 years. She had a history of thrombocytopenia of which cause has not yet been determined. She has no known underlying cancer. She has no history of miscarriage. Upon admission, she was fully conscious and alert. Her weight and height were 96 kg and 170 cm, respectively. Her initial blood pressure, heart rate, respiratory rate, and body temperature were 112/82 mmHg, 108 bpm, 20 bpm, and 37.9 c, respectively. She had swelling of both lower extremities more pronounced on the left side. After an initial assessment, color Doppler ultrasonography was done and revealed acute deep venous thrombosis. She was positive for lupus anticoagulant which suggested that antiphospholipid syndrome was the cause of her extensive thrombosis. Further, CT venography revealed partial thrombosis of the entire inferior vena cava (IVC) down to the common and external iliac veins and common femoral veins [Figure 1]. A ventilation-perfusion lung scintigraphy was requested to evaluate for pulmonary embolism. Imaging was carried out with Vertex V60 EPIC HP Gamma Camera System (ADAC Laboratories, USA) using a LEGP collimator. For the ventilation study, the patient inhaled 20 mCi of Tc-99m diethylenetriamine-pentaacetic acid aerosol and 6-view images of the lungs were obtained for 300 k counts per view. Immediately after the ventilation study, the lower extremity ascending RNV was done by injecting 3 mCi of Tc-99m macroaggregated albumin intravenously at the superficial vein of each feet with elastic bandages tied around both ankles. Anterior and posterior scintigraphic imaging started at the ankle level with the gamma camera moving proximally up to the upper abdomen at a speed of 20 cm/min. Then, immediately after the venogram was acquired, the 6-view perfusion lung images were obtained for 1200 k counts. A postexercise scan of the lower extremities was also done after the patient performed alternate leg raising for about 15 min during the time the perfusion lung scintigraphy was being acquired. The RNV revealed the absence of radiotracer activity in the deep venous system of bilateral lower extremities with the radiopharmaceutical shunting into numerous superficial collateral veins at the calves, thighs, pelvis, and the anterior abdominal wall. There was diminished radiopharmaceutical activity in the IVC with shunting into the paravertebral veins.[11] The postexercise scan revealed that there was retention of the radiopharmaceutical in both calves and faintly along the deep veins of the thighs and the iliac veins. These findings mirror that of the contrast-enhanced CT which indicate extensive thrombosis in the deep veins of both lower extremities up to the iliac veins and the IVC [Figure 2]. Upon examination of the lung scintigraphy, a large mismatched perfusion defect at the left lower lobe was seen which suggested pulmonary embolism. It was noticed that there is radiopharmaceutical activity accumulation in the upper abdomen which was seen in only the perfusion scan but not in the ventilation scan [Figure 3]. A SPECT/CT of the lung and upper abdomen was performed to better characterize these lesions and revealed that there was increased radiopharmaceutical uptake in segment 4 of the liver or the quadrate lobe [Figure 4]. The SPECT/CT of the lung also more clearly revealed the perfusion defect at the superior and basal segments of the left lung with no corresponding opacity on the CT image, which further consolidates the diagnosis of pulmonary embolism (image not shown).
DISCUSSION
This case highlights some interesting points. First, it demonstrates the strength of RNV and V/Q scan as an all-in-one modality for evaluation of a patient with VTE assessing the thrombotic burden in the extremities as well as in the lungs. RNV is a viable option for evaluation of patients suspected of having limb VTE with its high sensitivity and accuracy[123] and can serve as an alternative imaging modality in cases where Doppler ultrasonography is not feasible. This case also presents an uncommon finding in RNV which is the “hot quadrate lobe” sign secondary to IVC thrombosis causing systemic-portal shunting to the liver via the paraumbilical vein.[11] The hot quadrate lobe sign has been described in literature in planar RNV[1112] and contrast-enhanced CT,[13] but to the author's knowledge, this is the first report of this finding being demonstrated by SPECT/CT. Several causes of focal hepatic hotspots on nuclear medicine imaging have been described. Obstruction of either superior vena cava or IVC has been reported to result in hotspot in the quadrate lobe caused by collateral venous drainage through the umbilical or paraumbilical veins which in turn drain into the left branch of the portal vein resulting in “systemic-portal shunting,”[131415] while hepatic vein obstruction in Budd-Chiari syndrome is related with focal uptake in the caudate lobe.[16] Hepatic pathology including focal nodular hyperplasia,[17] regenerative nodules,[18] liver abscess, hemangioma, and hepatocellular carcinoma[19] have also been reported to accumulate radiocolloids, but can occur anywhere in the liver. This case highlights an example of the use of SPECT/CT as a hybrid imaging modality which can help provide valuable anatomical context to the functional aspect of nuclear medicine imaging. This point is further emphasized in this case since the SPECT/CT clearly demonstrated multiple segmental perfusion defects in the left lung where the corresponding CT revealed no parenchymal lung abnormality, which is indicative of pulmonary embolism. The planar V/Q scan also demonstrates these perfusion defects, but further imaging with SPECT/CT may provide improved visualization with additional anatomical correlation as in this case.[20]
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Conflicts of interest
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REFERENCES
- Radionuclide venography as an outpatient screening test for deep venous thrombosis. Ann Emerg Med. 1980;9:613-6.
- [Google Scholar]
- Radionuclide venography in the diagnosis of deep vein thrombosis of the lower extremities: A comparison to contrast venography. J Med Assoc Thai. 1998;81:432-41.
- [Google Scholar]
- Radionuclide venography in the diagnosis of deep vein thrombosis. Radiology. 1977;125:441-9.
- [Google Scholar]
- Radionuclide venography (RNV) in lower extremity venous disease. J Nucl Med. 1974;15:171-5.
- [Google Scholar]
- Effective doses in radiology and diagnostic nuclear medicine: A catalog. Radiology. 2008;248:254-63.
- [Google Scholar]
- Diagnostic value of Tc-99m MAA radionuclide venography of lower extremity: As a simultaneous procedure of ventilation-perfusion scan for pulmonary embolism. Gaoxiong Yi Xue Ke Xue Za Zhi. 1990;6:581-6.
- [Google Scholar]
- Frequent asymptomatic pulmonary embolism in patients with deep venous thrombosis. JAMA. 1994;271:223-5.
- [Google Scholar]
- Silent pulmonary embolism in patients with deep venous thrombosis. Incidence and fate in a randomized, controlled trial of anticoagulation versus no anticoagulation. J Intern Med. 1994;235:457-61.
- [Google Scholar]
- Unexpected high prevalence of silent pulmonary embolism in patients with deep venous thrombosis. Chest. 1989;95:498-502.
- [Google Scholar]
- Occult pulmonary embolism: A common occurrence in deep venous thrombosis. AJR Am J Roentgenol. 1987;148:263-6.
- [Google Scholar]
- Hot spots on liver scans associated with superior or inferior vena caval obstruction. Clin Nucl Med. 1994;19:622-9.
- [Google Scholar]
- Inferior vena cava obstruction with hot quadrate lobe on technetium-99m MAA scintivenography. Clin Nucl Med. 1986;11:731-2.
- [Google Scholar]
- Reflections on the etiology of hot spots on liver scans. Eur J Nucl Med. 1980;5:393-400.
- [Google Scholar]
- SPECT imaging in the diagnosis of Budd-Chiari syndrome. J Nucl Med. 1990;31:109-11.
- [Google Scholar]
- Hot spot liver scan in focal nodular hyperplasia. AJR Am J Roentgenol. 1980;135:1289-92.
- [Google Scholar]
- Nodular regenerative hyperplasia of the liver: Clinical and radiologic observations. AJR Am J Roentgenol. 1987;148:717-22.
- [Google Scholar]