Pulmonary arteriovenous malformations: diagnosis

Pulmonary arteriovenous malformations (PAVMs) are rare, abnormal low resistance vascular structures that connect a pulmonary artery to a pulmonary vein, thereby bypassing the normal pulmonary capillary bed and resulting in an intrapulmonary right-to-left shunt. The spectrum of PAVMs extends from microscopic lesions causing profound hypoxemia and ground glass appearance on computed tomography (CT) but with normal catheter angiographic findings to classic pulmonary aneurysmal connections that abnormally connect pulmonary veins and arteries. These malformations most commonly are seen in hereditary hemorrhagic telangiectasia (HHT). They are rarely due to secondary conditions such as post congenital heart disease surgery or hepatopulmonary syndrome (HPS). The main complications of PAVM result from intrapulmonary shunt and include stroke, brain abscess, and hypoxemia. Local pulmonary complications include PAVM rupture leading to life-threatening hemoptysis or hemothorax. The preferred screening test for PAVM is transthoracic contrast echocardiography (TTCE). CT has become the gold standard imaging test to establish the presence of PAVM. Endovascular occlusion of the feeding artery is the treatment of choice. Collateralization and recanalization of PAVM following treatment may occur, and hence long term clinical and imaging follow-up is required to assess PAVM enlargement and PAVM reperfusion.

Pulmonary vascular anatomy & anatomical variants

The vessels supplying the lungs include the pulmonary arteries, pulmonary veins, and bronchial arteries. The segmental and sub segmental pulmonary arteries parallel the bronchi and are named according to the bronchopulmonary segments they supply. There are however considerable anatomic variations, particularly in the upper lobes with variations in number or presence of accessory arteries from adjacent segments. The subsegmental pulmonary vein branches, run within interlobular septa and do not parallel the segmental or sub segmental pulmonary artery branches and bronchi. They converge to form right and left superior and inferior pulmonary veins which drain into the left atrium. Knowledge of normal and variant anatomy on cross-sectional and angiographic images is essential for accurate diagnosis of vascular pathology and aids planning of interventional procedures.

The significance of transient ischemic dilation in the setting of otherwise normal SPECT radionuclide myocardial perfusion images

BACKGROUND

Transient ischemic dilation (TID) in the setting of an abnormal SPECT radionuclide myocardial perfusion imaging (MPI) study is considered a marker of severe and extensive coronary artery disease (CAD). However, the clinical significance of TID and its association with CAD in patients with an otherwise normal MPI study is unclear.

METHODS

From a database of patients who underwent MPI over a 9-year period, 96 without known cardiac history who had normal image perfusion patterns, and who underwent coronary angiography within 6 months, were identified. TID quantitative values were derived. To adjust for varying stress and image protocols, a TID index based on published threshold values was derived for each patient, with >1 considered as TID. We examined the relationship of TID to the presence/extent of CAD, and to a CAD prognostic index. TID was also correlated with patient survival. To address referral bias, survival in a separate cohort of 3,691 patients with a normal perfusion MPI who did not undergo angiography in the 6-month interval was correlated with the presence and severity of TID.

RESULTS

For 28 (29.2%) patients with normal MPI perfusion patterns but with TID, there was no increased incidence of CAD, multivessel or left main disease, or a higher prognostic index compared with no TID. In addition, there was no increased mortality associated with TID in both the angiography cohort and in the patients who did not undergo immediate angiography.

CONCLUSIONS

TID in patients with an otherwise normal SPECT MPI study does not increase the likelihood of CAD, its extent or severity, and is not associated with worsened patient survival.

Pulmonary vasculitis: diagnosis and endovascular therapy

Pulmonary vasculitides are caused by a heterogeneous group of diseases with different clinical features and etiologies. Radiologic manifestations depend on the predominant type of vessel involved, which are grouped into large, medium, or small-sized vessels. Diagnosing pulmonary vasculitides is a challenging task, and radiologists play an important role in their management by providing supportive evidence for diagnosis and opportunities for minimally invasive therapy. This paper aims to present a practical approach for understanding the vasculitides that can affect the pulmonary vessels and lungs. We will describe and illustrate the main radiologic findings, discussing opportunities for minimally invasive treatment.

Evolving Concepts in the Diagnosis and Management of May–Thurner Syndrome

May–Thurner syndrome is a common cause of left lower extremity venous thrombosis resulting from repetitive and dynamic compression of the left common iliac vein by the right common iliac artery, commonly seen in young to middle-aged women. The diagnosis requires high clinical suspicion. Computed tomography venography and magnetic resonance venography depict the extent of venous thrombosis and iliac venous compression in patients with underlying thrombotic and nonthrombotic pathologies, respectively. Contrast venography allows detection of acute and chronic thrombus, associated venous obstruction, and collaterals but is of limited value to evaluate the early venous wall abnormalities. Endovascular ultrasound is highly useful to detect early mural changes and accurately quantify venous narrowing. Endovascular intervention with balloon dilatation and stenting with or without pharmacomechanical thrombectomy followed by long-term anticoagulation is the preferred treatment with excellent technical and clinical outcomes. This review focuses on the current understanding of the pathology, clinical presentation, and endovascular management of May–Thurner syndrome.

Marrow visualization on renal scintigraphy: an often-overlooked finding in azotemic patients

Delayed perfusion and enhanced hepatobiliary uptake are recognized findings on (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG3) scintigraphy in patients with renal insufficiency. Less well appreciated is the finding of bone marrow visualization. This study was performed to determine the frequency of this sign and to try to determine its association with laboratory parameters.

METHODS

We retrospectively studied medical records and the results of renal scans performed on 170 patients from June to December 2009 at the Montefiore Medical Center. Among them we identified 167 patients who fulfilled our inclusion criteria for participation in this study. Prominent individual vertebrae and sacroiliac joints were categorized as bone marrow visualization. A lack of radiotracer activity in individual vertebrae or in the sacroiliac joints was categorized as bone marrow nonvisualization. The studies were interpreted by 2 nuclear medicine physicians who were unaware of the laboratory and clinical data.

RESULTS

The 167 patients fulfilling our inclusion criteria were divided into 2 groups: group 1 (n = 20), with visualization, and group 2 (n = 147), without visualization. The mean creatinine level in group 1 was higher than that in group 2 (3.2 vs. 1.1, P = 0.001). There was no difference in mean hematocrit and hemoglobin between the 2 groups. None of the patients with a creatinine level less than 1.5 mg/dL had bone marrow visualization, whereas bone marrow was visualized in 44% of patients with a creatinine level greater than 1.5 mg/dL. There was no definite correlation between the intensity of marrow activity and the level of creatinine.

CONCLUSION

Bone marrow often may be visualized on early images of (99m)Tc-MAG3 renal scans of azotemic patients. The etiology needs further clarification. Enhanced marrow perfusion, an increased blood concentration of (99m)Tc-MAG3, and marrow hyperplasia secondary to associated anemia or hemolysis are possible causes.

Recurrent fracture of a recovery inferior vena cava filter with pulmonary migration

Inferior vena cava (IVC) filters are indicated in patients with venous thromboembolic disease in whom standard anticoagulation therapy is contraindicated or ineffective. A 32-year-old female presented to our hospital with chest pain 5 years after IVC filter placement. Imaging revealed sequential fracturing and embolization of two of the IVC filter arms to the pulmonary arteries. IVC filter fracture and subsequent migration to the lung is a rare complication. Systematic long-term follow-up in patients with IVC filters and, if possible, filter removal should be considered to prevent possible complications.

How I do it: percutaneous radiofrequency ablation (RFA)

Percutaneous radiofrequency ablation has seen increased utilization secondary to the rising incidence of renal cell carcinoma. This has been shown to be an effective and durable treatment especially in the elderly comorbid patient. In this article, we describe our technique and factors related to successful outcomes.