Bilateral inferior petrosal sinus sampling in the differential diagnosis of ACTH-dependent Cushing's syndrome: A reappraisal

Cushing's syndrome (CS) is a rare disorder, once exogenous causes have been excluded. However, when diagnosed, the majority of cases are adrenocorticotropic hormone (ACTH)-dependent, of which a substantial minority are due to a source outside of the pituitary, ectopic ACTH syndrome (EAS). Differentiating among pituitary-dependent CS, Cushing's disease (CD) and an ectopic source can be problematic. Because non-invasive tests in the evaluation of CS patients often lack adequate sensitivity and specificity, bilateral inferior petrosal sinus sampling (BIPSS), a minimally invasive procedure performed during the investigation of ACTH-dependent CS, can be extremely helpful. BIPSS is considered to be the gold standard for differentiating CD from the EAS. Furthermore, although such differentiation may indeed be challenging, BIPSS is itself a complex investigation, especially in recent times due to the widespread withdrawal of corticotrophin-releasing hormone and its replacement by desmopressin. We review current published data on this investigation and, in the light of this and our own experience, discuss its appropriate use in diagnostic algorithms.

Utilization of Intravascular Ultrasound in the Management of Venous Disease

As the field of Vascular and Interventional Radiology continues to grow, the variety of pathology treated, the approaches to treating various disease processes, and the vast options of equipment and devices continue to grow as well. Numerous venous disease processes have now become commonplace within the treatment realm of interventional radiologists and knowing how to approach each disease process is critical to successful management of these complex patients. A few of the most encountered venous disease processes include pelvic venous disorders, vena cava tumor involvement, venous thrombosis, and inferior vena cava filter placement; an understanding of the management of these processes is integral to the practice of today's interventional radiologists. Intravascular ultrasound (IVUS) has become increasingly important both in the diagnosis and in guiding treatment for venous disease. This article will describe in detail the multiple ways that IVUS can be used in the treatment of complex venous disorders.

Intravascular US: Applications in Interventional Radiology

Interventional radiology applications of intravascular US (IVUS) continue to expand, complementing intraprocedural angiography and providing a unique vantage from which to guide endovascular interventions. Vascular pathologic conditions become sonographically visualized rather than inferred from the planar appearance of the opacified vascular lumen. Perivascular targets become sonographically visualized rather than approximated on the basis of fluoroscopic landmarks. The authors introduce broad categories of IVUS catheters, namely radial and side-firing varieties, as well as prevailing options for each and their technical specifications. Common applications within interventional radiology are covered in a systems approach, including deep venous thrombosis, May-Thurner syndrome, nutcracker syndrome, transjugular intrahepatic portosystemic shunts, aortic interventions, peripheral arterial disease, and endovascular or perivascular biopsy. Discussions are accompanied by technical pearls from the authors, and summarized evidence where IVUS has been shown to reduce procedural time, intravascular contrast agent dose, radiation exposure, and morbidity in each space is presented. Finally, emerging applications and future directions are discussed. ^©RSNA, 2022.

Intravascular ultrasound in the diagnosis and treatment of central venous diseases

Intravascular ultrasound (IVUS) has been used extensively in coronary applications. Its use in venous applications has increased as endovascular therapy has increasingly become the mainstay therapy for central venous diseases. IVUS has been used for both diagnostic and therapeutic purposes in managing venous stenotic disease, venous occlusive disease, and IVC filter placement and removal. IVUS has been proven to be effective in providing detailed measurement of the venous anatomy, which aid in determining the appropriate size and the approach for venous stent placement. In IVC filter placement, IVUS can provide detailed measurement and guide IVC filter placement in emergent and critical care settings. It also has certain utility in filter removal. At any rate, to date there are only a few studies examining its impact on patient outcomes. Prospective randomized controlled trials are warranted in the future.

Intravascular Ultrasound for the Peripheral Vasculature-Current Applications and New Horizons

Intravascular ultrasound (IVUS) is a proven and rapidly developing imaging modality that can be used for a multitude of both diagnostic and interventional purposes. By allowing for superior intraluminal characterization, compared with angiography, IVUS has emerged as a technically valuable tool in interventional procedures such as transjugular intrahepatic portosystemic shunt/direct intrahepatic portosystemic shunt, venous interventions (May Thurner stenting, inferior vena cava filter placement, recanalization in the setting of chronic venous thrombosis/insufficiency), percutaneous fenestration in the setting of aortic dissection and angioplasty. Additional applications evaluating coronary arteries and plaque morphology have been described, but are outside the scope of this review. In addition to IVUS's merit as a pre- and intra-procedural guidance modality, there are also several advantages compared to the gold standard of angiography which include decreased need for iodinated contrast, decreased radiation exposure and decreased procedural times in certain cases. With current research, such as that aimed at supraharmonic imaging, further improvements in imaging depth, resolution and contrast to noise ratio are on the horizon.

Comparative analysis of technical success rates and procedural complication rates of bedside inferior vena cava filter placement by intraprocedural imaging modality

OBJECTIVE

Transabdominal duplex ultrasound, intravascular ultrasound (IVUS), and fluoroscopy have been used to assist with inferior vena cava filter (IVCF) placement since the late 1990s. We sought to compare the technical success and procedural complications of bedside placement of IVCF by the three commonly used modalities, namely, duplex ultrasound, IVUS, and combined IVUS and fluoroscopy.

METHODS

All published reports including prospective and retrospective cohort studies and case series with a minimum of 10 patients from inception to August 2017 were identified by an electronic search of PubMed and Embase. The studies were then pooled to create a sample of patient data for statistical analysis. Bonferroni correction was used for comparison of the three groups. Values of P < .017 (two tailed) were considered statistically significant for the pairwise comparisons.

RESULTS

A total of 21 studies comprising 2166 patients were identified. No significant differences were found in technical success and complication rates between the duplex ultrasound and IVUS arm, the combined IVUS and IVUS with fluoroscopy arm, or the duplex ultrasound and the combined IVUS with fluoroscopy arm. However, there was a trend toward decreased complication rates in the duplex ultrasound arm compared with the other two arms. A trend toward increased technical success was also observed in the combined IVUS and fluoroscopy arm compared with the other two arms.

CONCLUSIONS

There are no significant differences in the technical success and complication rates between the three commonly used modalities of bedside IVCF placement.

New method for ultrasound-guided inferior vena cava filter placement

OBJECTIVE

Transabdominal ultrasound (TAUS)-guided inferior vena cava filter (IVCF) placement currently uses an inferior vena cava (IVC) longitudinal plane with cross-section of the right renal artery or the transverse plane of the right renal vein (RRV)-IVC intersection. The goal of this study was to introduce a new method for TAUS-guided IVCF placement.

METHODS

The study enrolled patients who were at high risk for or had pulmonary embolism from October 22, 2010, to June 30, 2016. The probe was positioned on the right flank to centralize the RRV-IVC junction during imaging and to permit a straight line through the midpoint of the probe on the surface and a parallel line 1.0 cm below the straight line as a marker. The probe was subsequently placed on the abdominal wall with the upper edge at the marker line to show the long axis of the IVC during the process of filter placement. The upper edge of the probe was considered the filter tip position.

RESULTS

A total of 1029 patients were evaluated, and 98 patients (9.5%) were excluded because of poor IVC visualization (n = 14 [1.4%]), IVC or bilateral iliac vein thrombosis (n = 79 [7.7%]), and unsuitable anatomy (n = 5 [0.5%]). The remaining 931 patients (90.5%) were selected for TAUS-guided IVCF placement, and all filters (100%) were successfully placed. There were no procedure-related complications. Suprarenal IVCF was observed in 4 patients (0.4%) by computed tomography, and the filter tip exceeded the upper edge of L2 in 15 patients (1.6%) by plain film radiography; one of them had two RRVs. Severe filter tilting (20.8 degrees) occurred in one patient.

CONCLUSIONS

This new method of TAUS-guided IVCF placement was simple, safe, and effective. It may be widely applied for the bedside placement of vena cava filters.

Retrievable inferior vena cava filters for venous thromboembolism

Inferior vena cava (IVC) filters are used as an alternative to anticoagulants for prevention of fatal pulmonary embolism (PE) in venous thromboembolic disorders. Retrievable IVC filters have become an increasingly attractive option due to the long-term risks of permanent filter placement. These devices are shown to be technically feasible in insertion and retrieval percutaneously while providing protection from PE. Nevertheless, there are complications and failed retrievals with these retrievable filters. The aim of the paper is to review the retrievable filters and their efficacy, safety, and retrievability.