An innovative modification of the retrograde approach to angioplasty and recanalization of the superficial femoral artery

Endovascular therapy has been performed for chronic limb ischemia for nearly 50 years. Superficial femoral artery occlusions can be managed by the retrograde contralateral (“crossover”), antegrade ipsilateral, or retrograde popliteal (“facedown”) approaches. The retrograde approach was initially fraught with limitations and served as a backup option. Refinements to this technique have made it an enticing option and possibly the first choice in selected patients. We herein describe an innovative modification of this method.Endovascular therapy has been performed for chronic limb ischemia since 1964, with intraluminal and subintimal angioplasty of the superficial femoral artery (SFA) gaining popularity in the last decade (1). SFA occlusions can be managed by retrograde contralateral or antegrade ipsilateral approaches (2, 3); when these approaches fail, some practitioners resort to using a re-entry device (4, 5). The retrograde popliteal approach was initially fraught with limitations and served as a backup option (1, 4, 6). However, refinements to this technique have made this an enticing option (2–7), and it has been advocated as a first-line treatment in select patients (3). We herein describe another modification of this method.     

Development,growth, propagation,and angiographic utilization of the rabbit VX2 model of liver cancer: a pictorial primer and “how to” guide

The VX2 tumor is a leporine anaplastic squamous cell carcinoma characterized by rapid growth, hypervascularity, and facile propagation in the skeletal muscle. Since its introduction over 70 years ago, it has been used to model a variety of malignancies, and is commonly employed by interventional radiologists in preclinical investigations of hepatocellular carcinoma. However, despite the widespread and lasting popularity of the model, there are few technical resources detailing its use. Herein, we present a comprehensive pictorial outline of the technical methodology for development, growth, propagation, and angiographic utilization of the rabbit VX2 liver tumor model.The rabbit VX2 tumor model has played a longstanding role in experimental oncology. Developed in 1930–1940 by Rous et al. (1, 2), the VX2 tumor is a virus-induced anaplastic squamous cell carcinoma characterized by hypervascularity, rapid growth, and easy propagation in the skeletal muscle (3, 4). Since its introduction, the tumor has been used to model cancers of the head and neck (5), kidney (6), brain (7), lung (8), urinary bladder (9), uterus (10), liver (11, 12), bone (13), and pancreas (14). The high growth rate and the relatively large size of rabbit vasculature render the model particularly well suited for use by interventional radiologists, and in recent years the model has been employed in numerous studies pertaining to the imaging and locoregional treatment of hepatocellular carcinoma (15–19). However, despite the widespread and lasting popularity of the model, there are few, if any, comprehensive technical resources detailing its use, leaving many key procedural details to be conveyed anecdotally. Lack of a technical guide may also represent a barrier to entry of interventional radiologists into translational research. With that in mind, this review is intended to provide a complete pictorial overview of the development, growth, propagation, and angiographic utilization of the rabbit VX2 tumor model based on the experience of a single operator in order to serve as a reference for novice and experienced investigators alike.     

Diffusion-weighted MRI findings of treated and untreated retroperitoneal fibrosis

PURPOSE

We aimed to evaluate diffusion-weighted imaging (DWI) findings in patients with treated and untreated retroperitoneal fibrosis (RPF).

METHODS

We analyzed magnetic resonance imaging examinations of 44 RPF patients (36 male, 8 female), of which 15 were untreated and 29 were under therapy. Qualitative DWI and T1 postcontrast signal intensities and the largest perivascular extent of RPF were compared between treated and untreated groups and correlated to erythrocyte sedimentation rate and C-reactive protein values. Quantitative DWI signal intensities and apparent-diffusion-coefficients were calculated in regions-of-interest, together with a relative index between signal intensities of RPF and psoas muscle in 15 untreated patients and 14 patients under treatment with remaining perivascular fibrosis of more than 5 mm.

RESULTS

The extent of RPF in untreated patients was significantly larger compared with the extent of RPF in treated patients (P < 0.0001). DWI signal intensities were significantly higher in untreated patients than in patients under therapy (mean, 27 s/mm² vs. 20 s/mm²; P = 0.009). The calculated DWI-index was significantly higher in untreated patients than in patients under therapy (P = 0.003).

CONCLUSION

Our data show significant differences in the DWI findings (b800 signal intensities and relative DWI-index) of patients with treated and untreated RPF. DWI is a promising technique in the assessment of disease activity and the selection of patients suitable for medical therapy.Retroperitoneal fibrosis (RPF) is a rare disease affecting the retroperitoneal space (1–3). It presents as retroperitoneal proliferation of fibrous tissue surrounding the retroperitoneal vascular structures and abutting the medial aspect of the ureters. Clinical findings of RPF are non-specific; the most common symptom is chronic back pain. Further symptoms include lower extremity edema, deep vein thrombosis, oliguria, and urinary tract infection (3). Computed tomography (CT) and magnetic resonance imaging (MRI) are the preferred imaging modalities for the diagnosis of RPF (3). Retroperitoneal fibrosis shows contrast enhancement of gadolinium containing contrast media in MRI (4). Medical treatment is classically based on steroids like prednisone (3). Recent studies suggested tamoxifen as another safe and effective treatment alternative (5).The assessment of disease activity is relevant for planning of further medical or surgical therapy (6, 7). Nowadays the disease activity is assessable by positron emission tomography tracer uptake (3), with a relatively low resolution and the need of ionized radiation. As an alternative, dynamic contrast-enhanced MRI was suggested for the evaluation of disease activity (7, 8). However, gadolinium may be contraindicated in patients with impaired renal function due to the potential development of nephrogenic systemic fibrosis (NSF) (9). This is especially relevant in RPF patients with postrenal failure due to ureteral compression. For those cases a supplemental method for the determination of disease activity would be helpful.Diffusion-weighted imaging (DWI) is a radiation-free unenhanced MRI modality that has been applied for the detection of bowel inflammation in patients with chronic inflammatory bowel diseases (10, 11), as well as for oncological retroperitoneal and abdominal applications (12–14). Therefore, we aimed to evaluate the application and findings of DWI in patients with treated and untreated RPF disease.     

The potential role of modern US in the follow-up of patients with retroperitoneal fibrosis

PURPOSE

We aimed to evaluate a standardized ultrasonography (US) algorithm for the visualization of pathologic para-aortic tissue in retroperitoneal fibrosis (RPF).

MATERIALS AND METHODS

Thirty-five patients with lumbar RPF of typical extent, as determined by abdominal magnetic resonance imaging, were included. Examinations were conducted using standardized abdominal US with axial sections obtained at the levels of the renal arteries, aortic bifurcation, and both common iliac arteries. Imaging of each section was acquired with fundamental B-mode (US) and tissue harmonic imaging, respectively. In addition, we examined RPF visualized using extended field-of-view US.

RESULTS

Tissue harmonic imaging adequately visualized RPF of typical extent in 33 patients (94.2%). Excellent and good visualization with mild artifacts were achieved in 25 (71.4%) and six (17.1%) patients, respectively. When RPF spread along the iliac arteries, excellent visualization was achieved in 38.7% for the left side and 34.5% for the right side. There were significantly fewer diagnostic examinations for the right iliac (27.6%) than for the left one (9.7%) (P = 0.016). Overall, harmonic imaging achieved significantly better visualization than fundamental B-Mode (P < 0.001).

CONCLUSION

We described the first systematic evaluation of RPF visualization by modern US techniques. The best imaging quality was found in the typical RPF location, at the level of the aortic bifurcation. These results advocate for the presented US algorithm as an efficient follow-up alternative to cross-sectional imaging in RPF patients.Chronic periaortitis or retroperitoneal fibrosis (RPF) is a rare fibrosing disease that affects para-aortic tissues (1–3). It typically presents as a proliferating lumbar process surrounding the ureters and retroperitoneal vascular structures (Fig. 1) (2, 4). Sporadic, atypical manifestations in pelvic and mesenteric regions are also possible (5).Open in a separate windowFigure 1. a–c.Typical extent of the retroperitoneal fibrosis surrounding the infrarenal aorta (a). Spreading of the fibrosis to the renal arteries and along the common iliac arteries (b). Standardized US examination with four transverse sections (c). AO, aorta; AIC, common iliac artery; RA, renal artery; RPF, retroperitoneal fibrosis.Magnetic resonance imaging (MRI) allows precise evaluation of the extent and complications (6). RPF presents as hypointense (often isointense to striated muscle) plaques in native T1-weighted magnetic resonance (MR) images with significant gadolinium contrast enhancement of active and untreated retroperitoneal fibrosis (7–9).Ultrasonography (US) is primarily used in patients with RPF for a rapid and practical diagnosis of consecutive hydronephrosis (6). RPF presents as a smooth-bordered mass with either an echo-poor or echo-free signal (10, 11). Two studies in the 1980s indicated that US revealed only a poor overall sensitivity in the detection of RPF (12, 13). Feinstein et al. (14) reported that only 25% of affected patients with computed tomography (CT)-mediated diagnosis of RPF showed corresponding ultrasonographic abnormalities. Since that time the quality of US scanners has improved dramatically, and modern techniques, such as tissue harmonic imaging (THI) and extended field-of-view US, have significant advantages for routine clinical diagnosis (15–17). Today, US has established itself as an effective and cost-efficient imaging method for the screening and follow-up of infrarenal aortic aneurysms (18, 19). US, however, is not used routinely for RPF follow-up, nor has a systematic evaluation of modern ultrasonographic methods been available to date.The aim of the present study was to evaluate the potential role of modern ultrasonographic techniques for the visualization of fibrous tissue in patients with prediagnosed RPF.     

CT-guided percutaneous cryoablation of central lung tumors

PURPOSE

Cryoablation has been successfully used to treat lung tumors. However, the safety and effectiveness of treating tumors adjacent to critical structures has not been fully established. We describe our experience with computed tomography (CT)-guided percutaneous cryoablation of central lung tumors and the role of ice ball monitoring.

MATERIALS AND METHODS

Eight patients with 11 malignant central lung tumors (nine metastatic, two primary; mean, 2.6 cm; range, 1.0–4.5 cm) located adjacent to mediastinal or hilar structures were treated using CT-guided cryoablation in 10 procedures. Technical success and effectiveness rates were calculated, complications were tabulated and intraprocedural imaging features of ice balls were described.

RESULTS

All procedures were technically successful; imaging after 24 hours demonstrated no residual tumor. Five tumors recurred, three of which were re-ablated successfully. A hypodense ice ball with well-defined margin was visible during the first (n=6, 55%) or second (n=11, 100%) freeze, encompassing the entire tumor in all patients, and abutting (n=7) or minimally involving (n=4) adjacent mediastinal and hilar structures. Pneumothorax developed following six procedures (60%); percutaneous treatment was applied in three of them. All patients developed pleural effusions, with one patient requiring percutaneous drainage. Transient hemoptysis occurred after six procedures (60%), but all cases improved within a week. No injury occurred to mediastinal or hilar structures.

CONCLUSION

CT-guided percutaneous cryoablation can be used to treat central lung tumors successfully. Although complications were common, they were self-limited, treatable, and not related to tumor location. Ice ball monitoring helped maximize the amount of tumor treated, while avoiding critical mediastinal and hilar structures.Malignant lung tumors represent a major cause of morbidity and mortality in developed nations (1). While surgical resection remains the treatment of choice for the local control of both non-small cell lung cancer and metastases to the lung, percutaneous image-guided ablative therapies, particularly heat-based ablation techniques such as radiofrequency (RF) ablation, have emerged as safe and effective alternatives in patients who are not surgical candidates (2–7). However, treatment of lung tumors using RF ablation presents technical challenges, including high electrical resistance of alveolar air, poor thermal conductivity of aerated lung, and the heat-sink effect of blood and air flow in well-perfused and aerated lung tissue (8, 9). In addition, RF ablation has a limited role in the treatment of tumors that are close to mediastinal and hilar structures (2–9). Since intraprocedural visualization of ablation zone margins is not possible during heat-based ablation procedures, treatment of central tumors could harm mediastinal and hilar structures, including the tracheobronchial tree. As a result, tumors close to central structures are generally not amenable to treatment using percutaneous heat-based ablation techniques (2–10). Also, RF ablation may interfere with conduction system of the heart and function of the pacemakers (11).A growing body of literature describes the successful use of cryoablation in the treatment of malignancies in the liver, kidneys, and soft tissues (12–14). The ability to deploy multiple, individually-controlled cryoablation applicators facilitates the creation of ablation zones of desired shapes and sizes that can be tailored to the morphology of the tumor being ablated (15, 16). Cryoablation is also monitorable; ice balls can be visualized by computed tomography (CT) as a distinct ovoid area of low attenuation during the procedure. As a result, the treatment can be optimized while minimizing the risk of harming nearby critical structures (12–16). Also, cryoablation may be less painful than RF ablation (17). Finally, it has been suggested that cryoablation may be better suited for the treatment of thoracic tumors adjacent to the mediastinum because it spares the architecture of collagen-containing structures relative to RF ablation and enables preservation of the integrity of the tracheobroncheal tree (18). Heat-based ablation methods may not be safe in the treatment of central lung tumors because of a possibility of bronchial disruption or perforation, which may result in bronchopleural fistula formation (19). Although cryoablation has been used to treat lung malignancies (19–31), there are limited data on the safety and effectiveness of percutaneous cryoablation of central lung tumors. In this study, we describe our experience with CT-guided percutaneous cryoablation of central lung tumors and the role of ice ball monitoring.     

Single-stage endovascular treatment in patients with severe extracranial large vessel stenosis and concomitant ipsilateral unruptured intracranial aneurysm

PURPOSE

We aimed to evaluate the safety and effectiveness of single-stage endovascular treatment in patients with severe extracranial large vessel stenosis and concomitant ipsilateral unruptured intracranial aneurysm.

METHODS

Hospital database was screened for patients who underwent single-stage endovascular treatment between February 2008 and June 2013 and seven patients were identified. The procedures included unilateral carotid artery stenting (CAS) (n=4), bilateral CAS (n=2), and proximal left subclavian artery stenting (n=1) along with ipsilateral intracranial aneurysm treatment (n=7). The mean internal carotid artery stenosis was 81.6% (range, 70%–95%), and the subclavian artery stenosis was 90%. All aneurysms were unruptured. The mean aneurysm diameter was 7.7 mm (range, 5–13 mm). The aneurysms were ipsilateral to the internal carotid artery stenosis (internal carotid artery aneurysm) in five patients, and in the anterior communicating artery in one patient. The patient with subclavian artery stenosis had a fenestration aneurysm in the proximal basilar artery. Stenting of the extracranial large vessel stenosis was performed before aneurysm treatment in all patients. In two patients who underwent bilateral CAS, the contralateral carotid artery stenosis, which had no aneurysm distally, was treated initially.

RESULTS

There were no procedure-related complications or technical failure. The mean clinical follow-up period was 18 months (range, 9–34 months). One patient who underwent unilateral CAS experienced contralateral transient ischemic attack during the clinical follow-up. There was no restenosis on six-month follow-up angiograms, and all aneurysms were adequately occluded.

CONCLUSION

A single-stage procedure appears to be feasible for treatment of patients with severe extracranial large vessel stenosis and concomitant ipsilateral intracranial aneurysm.The concomitance of severe extracranial large vessel stenosis and unruptured ipsilateral distal intracranial aneurysm is often detected incidentally and their management is not clear (1). Although there are many studies in the literature that report different treatment approaches, there is no definite consensus on the management of the concomitant lesions (2–14). Various treatment options have been suggested, such as initial treatment of the aneurysm before revascularization of the stenosis, treating both lesions in the same surgical session and correcting the stenosis without treating the aneurysm (1, 5, 6, 9–11, 14–16). Few studies have reported single-stage endovascular treatment of both lesions as an effective method (17–19). On the other hand, the treatment of each lesion by this technique may lead to procedure-related undesired events such as cerebral ischemia/stroke or aneurysm rupture.In this study, we aimed to present the radiologic and clinical results of seven consecutive patients who underwent single-stage endovascular treatment of severe extracranial large vessel stenosis and concomitant unruptured ipsilateral intracranial aneurysm and discuss the safety and feasibility of this approach. In addition, distinct from the limited number of similar studies in the literature, we present our experience with bilateral carotid artery stenting (CAS) and proximal subclavian artery stenting during single-stage endovascular treatment.     

Targeted endovenous treatment of Giacomini vein insufficiency-associated varicose disease: considering the reflux patterns

PURPOSE

We aimed to assess the technical feasibility of targeted endovenous treatment of Giacomini vein insufficiency (GVI)-associated varicose disease and report our early results.

METHODS

We retrospectively screened 335 patients with varicose disease who underwent endovenous laser ablation from September 2011 to January 2013, and determined 17 patients who underwent Giacomini vein ablation. Using a targeted endovenous treatment approach considering the reflux pattern, all healthy great saphenous veins (GSV) or vein segments were preserved while all insufficient veins (Giacomini vein, perforator veins, small saphenous vein, anterior accessory GSV, major tributary veins, or incompetent segments of the GSV) were ablated. Treatment success was analysed using Doppler findings and clinical assessment scores before and after treatment.

RESULTS

Targeted endovenous treatment was technically successful in all cases. Seven GSVs were preserved totally and three GSVs were preserved partially (10/17, 58%), with no major complications. Clinical assessment scores and Doppler findings were improved in all cases.

CONCLUSION

Targeted endovenous treatment of GVI-associated varicose disease is safe and effective. In majority of GVI cases saphenous vein can be preserved using this approach.The Giacomini vein (GV) is defined as a branch of cranial extension of the small saphenous vein (SSV) that connects the SSV with the posterior thigh circumflex vein (PTCV) (1). In 14% of the population, SSV continues directly as the GV (2). Although most varices are caused by reflux originating from the great saphenous vein (GSV), SSV, or accessory saphenous branches, varicose disease caused by a Giacomini vein insufficiency (GVI) is not a rare condition (3, 4). GVI is commonly seen with varices that arise on the posterior thigh or calf and accounts for 4%–6% of cases treated by endovenous laser ablation (ELA) (5–8). There is no defined standard treatment for GVI-associated varicose disease. Performing a phlebectomy as the only treatment may result in recurrent varicose disease for some patients. Classical saphenous vein-focused surgical therapies may result in overtreatment or undertreatment. Targeted endovenous treatment (TET) differs from surgical treatments by focusing on the reflux sources and preserving healthy GSV, either totally or partially, while ablating insufficient segments of the vein. The ablation may be applied to any vein including the GV, perforator vein, SSV, and anterior accessory GSV, except the deep veins.ELA has recently evolved into an accepted option for eliminating truncal reflux for an incompetent GSV or SSV, with successful saphenous vein ablation rates ranging from 88% to 100% (9–12). However, reports of ELA treatment of the GVI are rare (3, 4, 7, 13). Some authors recommend only GSV ablation (4), while others ablate the insufficient GV (3). To the best of our knowledge, there is only one study on treatment of GVI considering the reflux pattern, which used both ELA and sclerotherapy (13). The present study focuses on the saphenous vein sparing effect of TET while treating the GVI by ELA and sclerotherapy.Today, reflux sources other than the saphenous veins, such as the perforator veins or GVs, are also accessible and can be treated selectively with the help of new endovenous techniques. TET considering the various reflux patterns is a minimally invasive and selective treatment method for GVI that may prevent unnecessary saphenous ablations in some cases. The purpose of this study was to evaluate the technical feasibility of TET and report early treatment results of 17 patients who had GVI with various reflux sources.     

MRI features of breast lymphoma: preliminary experience in seven cases

PURPOSE

We aimed to evaluate the imaging features of breast lymphoma using magnetic resonance imaging (MRI).

METHODS

This retrospective study consisted of seven patients with pathologically confirmed breast lymphoma. The breast lymphomas were primary in six patients and secondary in one patient. All patients underwent preoperative dynamic contrast-enhanced MRI and one underwent additional diffusion-weighted imaging (DWI) with a b value of 600 s/mm². Morphologic characteristics, enhancement features, and apparent diffusion coefficient (ADC) values were reviewed.

RESULTS

On MRI, three patients presented with a single mass, one with two masses, two with multiple masses, and one with a single mass and a contralateral focal enhancement. The MRI features of the eight biopsied masses in seven patients were analyzed. On MRI, the margins were irregular in six masses (75%) and spiculated in two (25%). Seven masses (87.5%) displayed homogeneous internal enhancement, while one (12.5%) showed rim enhancement. Seven masses (87.5%) showed a washout pattern and one (12.5%) showed a plateau pattern. The penetrating vessel sign was found in two masses (25%). One patient with two masses underwent DWI. Both masses showed hyperintense signal on DWI with ADC values of 0.867×10⁻³ mm²/s and 0.732×10⁻³ mm²/s, respectively.

CONCLUSION

Breast lymphoma commonly presents as a homogeneously enhancing mass with irregular margins and displays a washout curve pattern on dynamic MRI. A low ADC value may also indicate a possible diagnosis of breast lymphoma.Breast lymphoma, which constitutes only 0.04%–0.5% of all breast malignancies (1), can be divided into primary or secondary breast lymphoma (2). The majority of breast lymphomas are diffuse large B-cell lymphoma (3). The spontaneous regression of a breast lymphoma is rare and the five-year overall survival rate is 53% (1, 4). Early-stage identification and the use of radiotherapy are favorable prognostic factors, while mastectomy is associated with a poorer survival (1, 5). Therefore, a preoperative diagnosis of breast lymphoma would mean an earlier diagnosis and likely avoid unnecessary aggressive procedures.Previous studies demonstrated mammographic and ultrasonographic findings of breast lymphoma (6–8). Most lesions were high-density masses without spiculated margins and calcifications on mammography and noncircumscribed hypoechoic masses on ultrasonography (6–8). However, none were pathognomonic.Data on the magnetic resonance imaging (MRI) of breast lymphoma are limited to some single case reports (4, 7, 9–19) and small sample size case series (8, 20–23). The morphology and time-signal intensity curve (TIC) of breast lymphoma on MRI are variable. Diffusion-weighted imaging (DWI) is a functional imaging technique that is useful for distinguishing lymphoma from other malignant tumors in other systems (24, 25). However, to the best of our knowledge, the value of DWI in differentiating breast lymphoma from other malignant breast lesions has not been discussed. Therefore, the purpose of this study is to assess the MRI and DWI features of breast lymphoma.     

Clinical,pathological, and imaging characteristics of primitive neuroectodermal tumors of the spine

Primitive neuroectodermal tumors (PNETs) located in the spine are extremely rare, and information concerning these tumors in the medical literature is limited to single case reports. This pictorial essay presents the clinical, pathological, and imaging characteristics of PNET of the spine.Primitive neuroectodermal tumors (PNETs) are malignant tumors thought to arise from the neural ectoderm and comprise undifferentiated small round cells (1–3). PNETs located in the spine are extremely rare, and information concerning these tumors in the medical literature is limited to single case reports (4–5). This pictorial essay presents the clinical, pathological, and imaging characteristics of PNET of the spine.     

Imaging of facial nerve schwannomas: diagnostic pearls and potential pitfalls

Schwannomas are uncommon in the facial nerve and account for less than 1% of tumors of temporal bone. They can involve one or more than one segment of the facial nerve. The clinical presentations and the imaging appearances of facial nerve schwannomas are influenced by the topographical anatomy of the facial nerve and vary according to the segment(s) they involve. This pictorial essay illustrates the imaging features of facial nerve schwannomas according to their various anatomical locations and also reviews the pertinent differential diagnoses and potential diagnostic pitfalls.Facial nerve schwannomas (FNSs) are rare slow-growing tumors, accounting for less than 1% of all temporal bone tumors. They are typically solitary, unilateral, and sporadic in nature. FNSs may be bilateral as part of neurofibromatosis-2 spectrum (1, 2). Rarely, multiple schwannomas may involve peripheral branches of the facial nerve (FN) (3). The age of presentation varies from 5 to 84 years. No gender or side predilection is seen (4, 5).Histologically, FNSs are neuroectodermal in origin. They are encapsulated, benign tumors arising from the Schwann cells. They may show intratumoral cystic change and hemorrhage (3, 4, 5). Malignant schwannoma of the FN is extremely rare (6). FNSs commonly present with peripheral facial neuropathy and/or various otologic symptoms including sensorineural and conducting hearing loss (2–5). Facial paralysis is often seen at a later stage or may not be seen at all. The reasons for this are thought to be neuronal tolerance induced by the extremely slow growth of the tumor, abundant tumor vascularity, and commonly associated dehiscence of adjacent bone (7). Occasionally, FNSs may present as an intraparotid mass or as an intracranial lesion (2–5).The clinical presentations and the imaging appearances of FNSs are influenced by the topographical imaging anatomy of the FN and vary according to the segment(s) they involve (8). Here, we briefly describe the anatomy of the FN, followed by general imaging features of FNSs on computed tomography (CT) and magnetic resonance imaging (MRI), and appropriate imaging protocols. Tumor involving each segment is reviewed in relation to its characteristic clinical presentations emphasizing diagnostic pearls and potential pitfalls. The imaging examples of FNSs illustrated in this pictorial review are all histopathologically proven cases.     

Adverse effects of irreversible electroporation of malignant liver tumors under CT fluoroscopic guidance: a single-center experience

PURPOSE

We aimed to describe the frequency of adverse events after computed tomography (CT) fluoroscopy-guided irreversible electroporation (IRE) of malignant hepatic tumors and their risk factors.

METHODS

We retrospectively analyzed 85 IRE ablation procedures of 114 malignant liver tumors (52 primary and 62 secondary) not suitable for resection or thermal ablation in 56 patients (42 men and 14 women; median age, 61 years) with regard to mortality and treatment-related complications. Complications were evaluated according to the standardized grading system of the Society of Interventional Radiology. Factors influencing the occurrence of major and minor complications were investigated.

RESULTS

No IRE-related death occurred. Major complications occurred in 7.1% of IRE procedures (6/85), while minor complications occurred in 18.8% (16/85). The most frequent major complication was postablative abscess (4.7%, 4/85) which affected patients with bilioenteric anastomosis significantly more often than patients without this condition (43% vs. 1.3%, P = 0.010). Bilioenteric anastomosis was additionally identified as a risk factor for major complications in general (P = 0.002). Minor complications mainly consisted of hemorrhage and portal vein branch thrombosis.

CONCLUSION

The current study suggests that CT fluoroscopy-guided IRE ablation of malignant liver tumors may be a relatively low-risk procedure. However, patients with bilioenteric anastomosis seem to have an increased risk of postablative abscess formation.About 70% of hepatic metastases are nonresectable because of their anatomic location, the presence of comorbidities, or limited hepatic functional reserve (1). In these patients and in case of nonresectable primary liver tumors, percutaneous thermal ablation procedures, such as radiofrequency (RF) and microwave ablation, have become effective tools for treating hepatic malignancies (2–4). However, the effectiveness of RF and microwave treatment may be limited, either because of thermal damage to temperature-sensitive structures located in close proximity to the target tissue (5) or because of incomplete ablation of tumors adjacent to major hepatic vessels due to a phenomenon commonly termed “heat-sink effect” (6–10) which describes the loss of the applied thermal energy through the blood flow in those major vessels, whereby the effective energy application remains inadequate to ablate the target lesion.Irreversible electroporation (IRE) is a theoretically nonthermal ablation technique that delivers a series of high-voltage millisecond electrical pulses to the surrounding tissue, thus leading to irreversible disruption of the integrity of cell membranes and subsequent cell death by apoptosis (11–14). IRE may overcome the problems raised with thermal ablation: previous animal studies reported that bile ducts, blood vessels, nerves, and connective tissues are affected by IRE; however, regeneration is possible to some extent due to preservation of the tissue architecture (12, 13, 15–19). Moreover the feasibility of inducing cell death up to a vessel wall without any perivascular sparing was shown with IRE (12, 13, 18). The safety of IRE in the treatment of humans has been described (20). First reports have described potential complications after IRE, such as hemorrhage requiring blood transfusion (1.2%, two of 167 ablation procedures), portal vein thrombosis (3.2%, one of 31 ablation procedures), injury to bile ducts (1.8%, three of 167 ablation procedures), and infection (3.6%, six of 167 ablation procedures) (21, 22). However, few data are available for evaluating the potential risk factors associated with the occurrence of post-IRE complications.The purpose of this study was to review the frequency of mortality and morbidity after computed tomography (CT) fluoroscopy-guided liver IRE conducted at a single center and assess the factors influencing the occurrence of major complications.     

Reliability of semiquantitative assessment of osteophytes and subchondral cysts on tomosynthesis images by radiologists with different levels of expertise

PURPOSE

We aimed to assess reliability of the evaluation of osteophytes and subchondral cysts on tomosynthesis images when read by radiologists with different levels of expertise.

MATERIALS AND METHODS

Forty subjects aged >40 years had both knees evaluated using tomosynthesis. Images were read by an “experienced” reader (musculoskeletal radiologist with prior experience) and an “inexperienced” reader (radiology resident with no prior experience). Readers graded osteophytes from 0 to 3 and noted the presence/absence of subchondral cysts in four locations of the tibiofemoral joint. Twenty knees were randomly selected and re-read. Inter- and intrareader reliabilities were calculated using overall exact percent agreement and weighted κ statistics. Diagnostic performance of the two readers was compared against magnetic resonance imaging readings by an expert reader (professor of musculoskeletal radiology).

RESULTS

The experienced reader showed substantial intrareader reliability for graded reading of osteophytes (90%, κ=0.93), osteophyte detection (95%, κ=0.86) and cyst detection (95%, κ=0.83). The inexperienced reader showed perfect intrareader reliability for cyst detection (100%, κ=1.00) but intrareader reliability for graded reading (75%, κ=0.79) and detection (80%, κ=0.61) of osteophytes was lower than the experienced reader. Inter-reader reliability was 61% (κ=0.72) for graded osteophyte reading, 91% (κ=0.82) for osteophyte detection, and 88% (κ=0.66) for cyst detection. Diagnostic performance of the experienced reader was higher than the inexperienced reader regarding osteophyte detection (sensitivity range 0.74–0.95 vs. 0.54–0.75 for all locations) but diagnostic performance was similar for subchondral cysts.

CONCLUSION

Tomosynthesis offers excellent intrareader reliability regardless of the reader experience, but experience is important for detection of osteophytes.Tomosynthesis is a digital X-ray imaging technique that allows acquisition of tomographic information (1). In the literature, its use has been reported for imaging of lungs (1–4), breast (5–7), and head and neck region (8–10); for visualization of kidneys through intravenous pyelogram (11); for localization of an endorectal balloon for prostate image-guided radiation therapy (12); and for evaluation of aortic arch calcification (13), and bone and joint pathologies (14–21). While its clinical use has become common in chest and breast imaging, its clinical application in arthritis imaging is scarcely documented in the literature (14, 15, 22).In a recent study, we reported that tomosynthesis had higher sensitivity for detection of osteophytes and subchondral cysts compared to conventional radiography, using magnetic resonance imaging (MRI) findings as the reference standard (15). In that study, the readings were performed by a single expert musculoskeletal radiologist, and the intrareader reliability for this reader was reported as excellent (weighted κ=1.00 for osteophytes and 0.86 for subchondral cysts). Although it is known that reader experience is important for high reliability in radiographic assessment of knee osteoarthritis (23), it is not known whether excellent reliability can be achieved when tomosynthesis images are read by radiologists with different levels of experience.Tomosynthesis is a potentially useful tool in osteoarthritis research and might be used more frequently in the future because of its advantages over radiography. For its use to become more widespread, however, we need to understand whether reader experience affects the reliability of scoring osteoarthritis features on tomosynthesis, as it does with conventional radiography. It is possible that tomosynthesis can provide high reliability even with inexperienced readers because of the tomographic nature of the acquired images.The aim of this study was to determine the intrareader and inter-reader reliability for semiquantitative scoring of osteophytes and subchondral cyst detection using tomosynthesis, when read by radiologists with different levels of experience.     

Tempofilter II implantation in patients with lower extremity fractures and proximal deep vein thrombosis

PURPOSE

We aimed to examine the efficacy and safety of Tempofilter II (B. Braun, Melsungen, Germany) implantation to prevent pulmonary embolism in patients with lower-extremity fractures and proximal deep vein thrombosis (DVT).

MATERIALS AND METHODS

The records of patients with lower limb fractures and proximal DVT who were implanted with Tempofilter II devices from May 2004 to August 2009 were reviewed. Data collected included success rate, occurrence of pulmonary embolism, retrieval rate, and complications.

RESULTS

A total of 176 eligible patients, including 129 males (73.3%) and 47 females (26.7%) with a median age of 42.0 years (interquartile range [IQR], 34.0–52.0 years) were included in the study. Filters were successfully implanted in 174 patients (98.9%). One patient experienced a pulmonary embolism after implantation and died. Filters were removed without complications in all other patients. Median filter implantation time was 27 days (IQR, 25.0–29.0 days). Visible organized thrombi were present on the surface of 144 (82.8%) of filters after removal, and the diameter of most thrombi (n=124) ranged from 0.5 to 1.0 cm. Filters migrated <2 cm in 104 patients (59.8%) and ≥2 cm in five patients (2.9%). In these five cases, three filters migrated into the right atrium and two migrated to the orifice of the renal veins.

CONCLUSION

Tempofilter II is safe and may be useful in cases of lower extremity fracture with proximal DVT for the prevention of pulmonary embolism. The filter is easily placed and retrieved, and associated with minimal complications.Acute pulmonary embolism (PE) is one of the most common causes of death in hospitalized patients (1, 2). The mortality rate of PEs is especially high in trauma patients, as these tend to develop latent PEs. Although the mortality associated with PEs has been greatly reduced by the application of inferior vena cava filters (VCFs) (3, 4), permanent VCF implantation is associated with long-term complications such as recurrent deep vein thrombosis (DVT), filter dislocation, migration, and rupture (5–8). Thus, for patients with a long life expectancy and transient risk for venous thromboembolism, nonpermanent VCF placement is preferred (6). Currently, two types of nonpermanent filters are available: temporary and retrievable filters. Retrievable filters can be used to prevent PE in trauma patients during the high-risk period while avoiding the complications associated with long-term placement (9, 10). If a thrombus is trapped by the filter, the filter can be maintained at the original position and removed after thrombus resolution (5). However, because the recommended usage time of this type of filter is relatively short (usually 12 days), the extraction rate is low and many are left in place permanently (11).The Tempofilter II (B. Braun, Melsungen, Germany) is a second-generation temporary caval filter with an indwelling time of up to six weeks (12). The filter is placed and retrieved by means of a tethered cable fixed to a subcutaneous anchoring device. There is only one prior large-scale study, including placement of 104 Tempofilter II filters in 103 patients with PE, DVT, or both (12). They reported only one case of PE after filter placement, no mechanical complications related to the filter, and successful retrieval in all but one case regardless of thrombus entrapment (12).The purpose of this study was to examine the efficacy and safety of the Tempofilter II in Chinese patients with lower extremity fractures and proximal DVT.     

Genotype-phenotype correlations in hepatocellular adenoma: an update of MRI findings

Hepatocellular adenoma (HCA) is a generally benign liver tumor with the potential for malignancy and bleeding. HCAs are categorized into four subtypes on the basis of genetic and pathological features: hepatocyte nuclear factor 1α-mutated HCA, β-catenin-mutated HCA, inflammatory HCA, and unclassified HCA. Magnetic resonance imaging (MRI) plays an important role in the diagnosis, subtype characterization, and detection of HCA complications; it is also used to differentiate HCA from focal nodular hyperplasia. In this review, we present an overview of the genetic abnormalities, oncogenesis, and typical and atypical MRI findings of specific subtypes of HCA using contrast-enhanced MRI with or without hepatobiliary contrast agents (gadobenate dimeglumine and gadoxetate disodium). We also discuss their different management implications after diagnosis.Hepatocellular adenoma (HCA) is a rare, benign tumor of the liver that occurs predominantly in young and middle-aged women (1). In contrast to focal nodular hyperplasia (FNH), HCA may involve complications, such as a life-threatening bleeding and malignant degeneration (1–3). The strong association between the occurrence of HCA and the use of oral contraceptives was first acknowledged in 1970s (4), and the incidence of HCA is now thought to be 30 times greater in oral contraceptive users compared to nonusers (5, 6). A dose-dependent association and spontaneous regression following the withdrawal of estrogens have also been described (4, 7). However, the exact role of estrogen in HCA is still poorly understood.In this review, we present an overview of the typical and atypical magnetic resonance imaging (MRI) findings of different HCAs compared to FNH, and discuss various pitfalls that may be encountered with MRI.     

Traumatic diaphragmatic injury: a review of CT signs and the difference between blunt and penetrating injury

PURPOSE

We aimed to present the frequency of computed tomography (CT) signs of diaphragmatic rupture and the differences between blunt and penetrating trauma.

MATERIALS AND METHODS

The CT scans of 23 patients with surgically proven diaphragmatic tears (both blunt and penetrating) were retrospectively reviewed for previously described CT signs of diaphragmatic injuries. The overall frequency of CT signs was reported; frequency of signs in right- and left-sided injuries and blunt and penetrating trauma were separately tabulated and statistically compared.

RESULTS

The discontinuous diaphragm sign was the most common sign, observed in 95.7% of patients, followed by diaphragmatic thickening (69.6%). While the dependent viscera sign and collar sign were exclusively observed in blunt-trauma patients, organ herniation (P = 0.05) and dangling diaphragm (P = 0.0086) signs were observed significantly more often in blunt trauma than in penetrating trauma. Contiguous injury on either side of the diaphragm was observed more often in penetrating trauma (83.3%) than in blunt trauma (17.7%).

CONCLUSION

Knowledge of the mechanism of injury and familiarity with all CT signs of diaphragmatic injury are necessary to avoid a missed diagnosis because there is variability in the overall occurrence of these signs, with significant differences between blunt and penetrating trauma.Traumatic diaphragmatic injury has been found in 3%–8% of patients undergoing surgical exploration after blunt trauma and in 10% of patients with penetrating trauma (1, 2). The rate of initially missed diagnoses on computed tomography (CT) ranges from 12% to 63%. A missed diagnosis can later present as intrathoracic visceral herniation and strangulation with a mortality rate of 30%–60% (2, 3). In this era of increasing nonoperative management for most cases of blunt abdominal trauma, it becomes essential to diagnose diaphragmatic rupture on imaging to ensure early and timely operative repair of the rupture. The reasons for missed early diagnoses include potentially distracting and more severe thoracic and abdominal visceral injuries and lack of familiarity with all the imaging appearances and signs of diaphragmatic rupture (2, 4).Various imaging modalities including chest radiographs, ultrasonography, CT, and magnetic resonance imaging have been used in the diagnosis of diaphragmatic rupture (1). Currently, multidetector CT (MDCT) is the modality of choice for the detection of diaphragmatic injury. MDCT has increased the accuracy of diagnosis of diaphragmatic rupture. MDCT has inherent technical advantages, such as rapid, volumetric data acquisition for the chest and abdomen within a single breath hold, minimization of motion artifacts, thin-section reconstruction and sagittal and coronal reformat-reducing partial-volume effects that assist in diagnosing subtle defects (1). MDCT also aids in detecting the associated chest, abdomen, ribs, and bony injuries in these polytrauma patients. Various studies have revealed CT to have a variable sensitivity and specificity of 61%–87% and 72%–100%, respectively, for the diagnosis of diaphragmatic rupture (1, 5–7). Killeen et al. (6) demonstrated that the sensitivity for detecting left-sided ruptures (78%) is higher than for right-sided ruptures (50%). This finding has been attributed to the better soft tissue-fat contrast on the left side and the difficulty in diagnosing subtle liver herniation on the right side.Various signs of diaphragmatic rupture have been described on CT. These signs have been divided into direct and indirect signs and signs of uncertain/controversial origin, according to Desir and Ghaye (8), and have been tabulated in 2, 3).

Table 1.

CT signs of diaphragmatic injury^a

Use of shear wave elastography to differentiate benign and malignant breast lesions

PURPOSE

We aimed to determine the correlations between the elasticity values of solid breast masses and histopathological findings to define cutoff elasticity values differentiating malignant from benign lesions.

MATERIALS and METHODS

A total of 115 solid breast lesions of 109 consecutive patients were evaluated prospectively using shear wave elastography (SWE). Two orthogonal elastographic images of each lesion were obtained. Minimum, mean, and maximum elasticity values were calculated in regions of interest placed over the stiffest areas on the two images; we also calculated mass/fat elasticity ratios. Correlation of elastographic measurements with histopathological results were studied.

RESULTS

Eighty-three benign and thirty-two malignant lesions were histopathologically diagnosed. The minimum, mean, and maximum elasticity values, and the mass/fat elasticity ratios of malignant lesions, were significantly higher than those of benign lesions. The cutoff value was 45.7 kPa for mean elasticity (sensitivity, 96%; specificity, 95%), 54.3 kPa for maximum elasticity (sensitivity, 95%; specificity, 94%), 37.1 kPa for minimum elasticity (sensitivity, 96%; specificity, 95%), and 4.6 for the mass/fat elasticity ratio (sensitivity, 97%; specificity, 95%).

CONCLUSION

SWE yields additional valuable quantitative data to ultrasonographic examination on solid breast lesions. SWE may serve as a complementary tool for diagnosis of breast lesions. Long-term clinical studies are required to accurately select lesions requiring biopsy.Breast cancer is associated with high morbidity; ∼1.38 million new cases and 458 000 deaths occur annually worldwide (1). Breast cancer is by far the most common cancer in females of both developed and developing countries, and remains a major public health problem.Annual mammographic screening is valuable for early detection of breast cancer, reducing mortality and morbidity, particularly of patients with tumors in fatty breast tissue (2). Increase in breast tissue density over time is a serious problem; this reduces the diagnostic accuracy of breast cancer, especially in younger females (3). Thus, as the proportion of glandular breast tissue rises, other imaging methods are required (4).Gray-scale ultrasonography is a valuable adjunct to mammography and other breast imaging methods, affording highly sensitive assessment of breast masses and differentiating benign solid breast lesions from those that are malignant (5–7). However, ultrasonography is strongly subjective and poorly specific (8–10).Breast biopsy remains the gold standard for definitive diagnosis of suspicious breast lesions. Although the total number of females referred for interventional diagnostic procedures represents a small percentage of any screened population, the healthcare resources consumed by such females are disproportionately high (11). Further, the pathological result is benign in up to 75% of all cases (11–13). Therefore, a reliable, noninvasive, costeffective method helping to differentiate benign from malignant breast lesions, thus reducing the number of unnecessary interventional diagnostic procedures, would be valuable.Sonoelastography uses ultrasound to assess tissue stiffness (elasticity), which can be described using Young’s modulus: E=σ/ε, where σ is the applied stress and ε the resultant tissue deformation. Two principal sonoelastographic approaches are available; these are static (strain) and transient (vibration; shear wave) elastography. In static elastography, a transducer is used to compress tissue and the resulting strain is presented as a color map of tissue elasticity superimposed on the real-time gray-scale sonogram.Static elastography is associated with significant interobserver variability, and uses elastographic scoring (ES) or strain ratio (SR) measurement as a diagnostic parameter. Both ES and SR are subjective semi-quantitative measures (14, 15). Shear wave elastography (SWE) is a novel technique applicable to soft tissue. In SWE, transverse shear waves spreading laterally from the tissue are tracked, and the speed of propagation calculated. SWE yields real-time quantitative data and is highly reproducible compared to static elastography (16, 17). Reproducibility of the latter technique is considered to be a major problem and may compromise patient outcomes. Thus, further work on the utility of SWE is needed.In the present study we sought to correlate the SWE values of a series of solid breast masses with histopathological findings, and to determine cutoff elasticity values allowing benign and malignant tumors to be distinguished.     

Efficacy of CT in diagnosis of transudates and exudates in patients with pleural effusion

PURPOSE

We aimed to evaluate the efficacy of multidetector computed tomography (CT) imaging in diagnosis of pleural exudates and transudates using attenuation values.

MATERIALS AND METHODS

This retrospective study included 106 patients who were diagnosed with pleural effusion between January 2010 and June 2012. After the patients underwent chest CT, thoracentesis was performed in the first week. The attenuation values of the pleural effusions were measured in all patients.

RESULTS

According to Light’s criteria, 30 of 106 patients with pleural effusions had transudates, and the remaining patients had exudates. The Hounsfield unit (HU) value of the exudates (median, 12.5; range, 4–33) was significantly higher than that of the transudates (median, 5; range, 2–15) (P = 0.001). Additionally, when evaluated by disease subgroups, congestive heart failure and empyema were predictable in terms of median HU values of the pleural effusions with high and moderate sensitivity and specificity values (84.6% and 81.2%, respectively; 76.9% and 66.7%, respectively). Compared with other patients, the empyema patients had significantly more loculation and pleural thickening.

CONCLUSION

CT attenuation values may be useful in differentiating exu-dates from transudates. Although there is an overlap in most effusions, exudate can be considered when the CT attenuation values are >15 HU. Because of overlapping HU values, close correlation with clinical findings is essential. Additional signs, such as fluid loculation and pleural thickness, should be considered and may provide further information for the differentiation.Pleural effusion is a common clinical problem; indeed, it can arise from many diseases (1, 2). The first step in assessing a pleural effusion is to decide whether the pleural fluid is a transudate or an exudate (3). Transudate is caused by imbalances in hydrostatic and oncotic forces. It results from diseases such as heart failure, kidney failure, and cirrhosis. However, an exudate occurs when local factors influencing the accumulation of pleural fluid are altered. Exudates can be caused by clinical conditions such as pneumonia, malignancy, and thromboembolism (4).Although clinical and radiological findings may provide significant evidence about the cause(s) of pleural effusion(s), it may still be necessary to evaluate some cases with diagnostic thoracentesis (4, 5). Clinically, exudative effusion can be successfully separated from transudative effusion using Light’s criteria. The nature of the pleural effusion is based on diagnostic thoracentesis (1, 2). However, computed tomography (CT) can be used to evaluate the nature of pleural effusions to avoid the complications of thoracentesis (6, 7). Features such as pleural nodules, pleural thickening, loculation, extrapleural fat tissue thickness, and effusion density can be evaluated by CT to discriminate between exudates and transudates (8). Only two reported studies have examined CT attenuation values in patients with pleural effusions (9, 10); these showed different attenuation values for evaluation of pleural effusions.The aim of the present study was to evaluate the efficacy of multidetector CT (MDCT) images in diagnosing pleural exudates and transudates using attenuation values.     

Adrenal venous sampling for stratifying patients for surgery of adrenal nodules detected using dynamic contrast enhanced CT

PURPOSE

We aimed to assess the value of adrenal venous sampling (AVS) for diagnosing primary aldosteronism (PA) subtypes in patients with a unilateral nodule detected on adrenal computed tomography (CT) and scheduled for adrenalectomy.

MATERIALS AND METHODS

This retrospective study included 80 consecutive patients with PA undergoing CT and AVS. Different lateralization indices were assessed, and a cutoff established using receiver operating characteristic curve analysis. The value of CT alone versus CT with AVS for differentiating PA subtypes was compared. The adrenalectomy outcome was assessed, and predictors of cure were determined using univariate analysis.

RESULTS

AVS was successful in 68 patients. A cortisol-corrected aldosterone affected-to-unaffected ratio cutoff of 2.0 and affected-to-inferior vena cava ratio cutoff of 1.4 were the best lateralization indices, with accuracies of 82.5% and 80.4%, respectively. CT and AVS diagnosed 38 patients with aldosterone-producing adenomas, five patients with unilateral adrenal hyperplasia, and 25 patients with bilateral adrenal hyperplasia. Of the 52 patients with a nodule detected on CT, subsequent AVS diagnosed bilateral adrenal hyperplasia in 14 patients (27%). Compared to the results of combining CT with AVS, the accuracy of CT alone for diagnosing aldosterone-producing adenomas was 71.1% (P < 0.001). The cure rate for hypertension after adrenalectomy was 39.2%, with improvement in 53.5% of patients. On univariate analysis, predictors of persistent hypertension were male gender and preoperative systolic blood pressure.

CONCLUSION

To avoid inappropriate surgery, AVS is necessary for diagnosing unilateral nodules with aldosterone hypersecretion detected by CT.Primary aldosteronism (PA) is the most common form of secondary hypertension, with a prevalence of 5%–11% (1–3). PA is due primarily to the hypersecretion of aldosterone by an aldosterone-producing adenoma (APA) or unilateral (primary) adrenal hyperplasia (UAH), which constitute 30%–40% of cases; the remainder are presumed to be secondary to idiopathic bilateral adrenal hyperplasia (BAH) (1, 4, 5). APA and UAH are two forms of unilateral aldosterone hypersecretion, and both are curable with adrenalectomy. BAH induces bilateral aldosterone hypersecretion, and anti-aldosterone drugs are used in its medical management (5–7).The plasma aldosterone-to-renin ratio is used to screen for PA in patients at high risk for PA (8). Recent guidelines recommend using computed tomography (CT) of the adrenal gland to categorize the subtype after confirming PA. However, CT cannot reliably visualize a microadenoma or distinguish between an incidentaloma or BAH and APA. It has been suggested that adrenal venous sampling (AVS) be performed to determine the subtype of PA and to differentiate between unilateral and bilateral production of aldosterone preoperatively (9). AVS to measure the adrenal vein aldosterone and cortisol is the gold standard for lateralizing aldosterone secretion (10). Lateralization is defined using several ratios. In patients with APA or UAH, a unilateral adrenalectomy results in a complete cure or improved hypertension and potassium normalization in approximately 30% of patients, with reported rates up to 86% (11–15).This study assessed several lateralization ratios to establish the most predictive of unilateral disease. We also compared the CT results with those of bilateral AVS for differentiating the PA subtype, with the assumption that AVS is necessary before surgery, even in patients with nodules <10 mm detected with CT. Finally, we assessed the outcomes of adrenalectomy in our patients to identify preoperative predictors of a good outcome.     

Comparison of diffusion-weighted MRI acquisition techniques for normal pancreas at 3.0 Tesla

PURPOSE

We aimed to optimize diffusion-weighted imaging (DWI) acquisitions for normal pancreas at 3.0 Tesla.

MATERIALS AND METHODS

Thirty healthy volunteers were examined using four DWI acquisition techniques with b values of 0 and 600 s/mm² at 3.0 Tesla, including breath-hold DWI, respiratory-triggered DWI, respiratory-triggered DWI with inversion recovery (IR), and free-breathing DWI with IR. Artifacts, signal-to-noise ratio (SNR) and apparent diffusion coefficient (ADC) of normal pancreas were statistically evaluated among different DWI acquisitions.

RESULTS

Statistical differences were noticed in artifacts, SNR, and ADC values of normal pancreas among different DWI acquisitions by ANOVA (P < 0.001). Normal pancreas imaging had the lowest artifact in respiratory-triggered DWI with IR, the highest SNR in respiratory-triggered DWI, and the highest ADC value in free-breathing DWI with IR. The head, body, and tail of normal pancreas had statistically different ADC values on each DWI acquisition by ANOVA (P < 0.05).

CONCLUSION

The highest image quality for normal pancreas was obtained using respiratory-triggered DWI with IR. Normal pancreas displayed inhomogeneous ADC values along the head, body, and tail structures.Diffusion-weighted magnetic resonance imaging (DW-MRI) has increasingly expanded to abdominal organs thanks to newer technical developments. Diffusion-weighted imaging (DWI) can provide great details of functional and anatomic information that can be used in the differential diagnosis of abdominal pathological conditions. Investigators have recently reported that DWI can be utilized to detect pancreatic cancer (1, 2) and analysis of apparent diffusion coefficient (ADC) can help differentiate pancreatic masses (3–6). The single-shot spin-echo echo-planar imaging combined with parallel imaging technique is commonly employed for pancreatic DWI studies. Breath-hold DWI is the most common technique used for signal acquisition, especially on 1.5 Tesla (T) magnetic resonance (MR) system, because of its time efficiency. However, there are several disadvantages of breath-hold DWI, including poor signal-to-noise ratio (SNR), limited scan volume and significant artifacts (7, 8). Respiratory-triggered and free-breathing techniques are also used for signal acquisition in pancreatic DWI studies. Compared to breath-hold, the advantages of respiratory-triggered and free-breathing techniques are higher SNR due to multiple signal acquisitions, larger scanning range and less artifacts; their main disadvantage being the longer scanning time (9). Additionally, techniques of fat suppression, such as chemical shift selective (CHESS) and short tau inversion recovery, are essential for DWI in the pancreas for improving the contrast ratio and contrast-to-noise ratio of lesions with respect to normal pancreatic tissues (1, 6, 10).Previously, most investigations were performed using 1.5 T MR scanners. Pancreas imaging using DWI with 3.0 T MR system needs to be further clarified and understood due to its increasing application, which may be a challenging task because of specific absorption rate and various artifacts from high sensitivity to magnetic field inhomogeneity and physiological movement (11). The aim of this study was to investigate different DWI techniques to visualize normal pancreas using a 3.0 T MR scanner and determine the best image acquisition technique in terms of artifacts, SNR, and ADC.     

Imaging and pathology findings after an initial negative MRI-US fusion-guided and 12-core extended sextant prostate biopsy session

PURPOSE

A magnetic resonance imaging-ultrasonography (MRI-US) fusion-guided prostate biopsy increases detection rates compared to an extended sextant biopsy. The imaging characteristics and pathology outcomes of subsequent biopsies in patients with initially negative MRI-US fusion biopsies are described in this study.

MATERIALS AND METHODS

We reviewed 855 biopsy sessions of 751 patients (June 2007 to March 2013). The fusion biopsy consisted of two cores per lesion identified on multiparametric MRI (mpMRI) and a 12-core extended sextant transrectal US (TRUS) biopsy. Inclusion criteria were at least two fusion biopsy sessions, with a negative first biopsy and mpMRI before each.

RESULTS

The detection rate on the initial fusion biopsy was 55.3%; 336 patients had negative findings. Forty-one patients had follow-up fusion biopsies, but only 34 of these were preceded by a repeat mpMRI. The median interval between biopsies was 15 months. Fourteen patients (41%) were positive for cancer on the repeat MRI-US fusion biopsy. Age, prostate-specific antigen (PSA), prostate volume, PSA density, digital rectal exam findings, lesion diameter, and changes on imaging were comparable between patients with negative and positive rebiopsies. Of the patients with positive rebiopsies, 79% had a positive TRUS biopsy before referral (P = 0.004). Ten patients had Gleason 3+3 disease, three had 3+4 disease, and one had 4+4 disease.

CONCLUSION

In patients with a negative MRI-US fusion prostate biopsy and indications for repeat biopsy, the detection rate of the follow-up sessions was lower than the initial detection rate. Of the prostate cancers subsequently found, 93% were low grade (≤3+4). In this low risk group of patients, increasing the follow-up time interval should be considered in the appropriate clinical setting.Prostate cancer is the most common cancer in males, with an estimated 238 590 new diagnoses annually in the USA, and it is the second leading cause of cancer-related mortality in males (1). One in six males will develop prostate cancer in his lifetime (1). The current standard of care for diagnosing and grading prostate cancer is a 12-core extended sextant biopsy obtained with transrectal ultrasonography (TRUS) guidance (2, 3). As magnetic resonance imaging (MRI) has superior contrast resolution than ultrasonography (US), it is possible for multiparametric MRI (mpMRI) to detect prostate cancer with high reliability (4). Since clinically insignificant cancer is often invisible to magnetic resonance (MR), prostate MRI preferentially detects more aggressive cancers (5–9). MRI can be used to guide the prostate biopsy, either using a direct “in-gantry” approach or by using MRI-US fusion, which was developed as an office-based alternative (10). MRI-US targeted biopsies have about twice the per-core detection rate of sextant biopsies (11), and have been shown to be particularly useful for prostates measuring greater than 40 mL, which typically have lower rates of cancer detection than smaller prostate glands (12).Since TRUS-guided biopsies have a relatively low sensitivity, many patients with a rising prostate-specific antigen (PSA), but an initial negative biopsy, undergo additional biopsies with progressively lower yields. In a study of sequential systematic biopsies in 1051 males, the detection rate of successive biopsies was 22%, 10%, 5%, and 4%, respectively (13). The third and fourth TRUS-guided biopsy sessions detected lower grade cancers and were found to have higher morbidity than the first two biopsies. Recently, MRI-US fusion biopsy has been reported to increase cancer detection rates in the setting of a prior negative TRUS biopsy (14, 15).While MRI-US fusion biopsy is promising in the setting of previous negative random sampling, the response to a negative MRI-US fusion biopsy is less clear. Since a MRI-US fusion biopsy increases prostate cancer detection, this population should have a lower disease burden than patients with an initial negative TRUS-guided biopsy alone. Now that MRI-US fusion biopsies have been available for several years, such data are beginning to accumulate. Here, we investigate the detection rates of subsequent biopsies in patients with an initial negative MRI-US fusion prostate biopsy.