John D. Millet

Complications following vascular procedures in the upper extremities: a sonographic pictorial review.

Abstract The arteries of the upper extremities are increasingly utilized to gain access for angiography, percutaneous coronary interventions, endovascular therapy, and continuous hemodynamic monitoring. Hence, complications after upper-extremity arterial interventions are increasing in incidence. Similarly, the incidence of upper-extremity deep venous thrombosis is increasing as venous access is increasingly achieved with upper-extremity central line placement. Knowledge of the sonographic appearance of these complications is essential as ultrasound is often the only imaging modality used in the evaluation of suspected vascular injury. This pictorial review demonstrates the spectrum of complications observed following vascular procedures in the upper extremities, including thrombosis, hematoma, pseudoaneurysm, arteriovenous fistula, and arterial dissection. Gray-scale, color, and pulsed Doppler imaging findings are described, and pertinent management issues, including endovascular and surgical therapies, are briefly discussed.

Carotid stent deformation: Sonographic findings and CT correlation

Carotid artery dissection is a rare but potentially serious complication of endovascular procedures in the carotid arteries. Stent deformation or incomplete expansion may occur following endovascular repair of an iatrogenic carotid artery dissection and may mimic stent fracture. We report an unusual case of deformation of a common carotid artery open cell design stent following endovascular repair of an iatrogenic dissection, which resulted in persistent blood flow between the stent and the wall of the common carotid artery. Sonographic features are described and correlation with intravascular ultrasound and CT is provided.

Large Ovarian Calcifications From an Unresorbed Corpus Albicans

Large calcifications in otherwise normal-appearing ovaries are infrequently seen on sonography, and their diagnostic importance is often unclear. There is a paucity of information on the imaging findings of calcified corpora albicantia in the radiologic literature,1–4 especially on sonography. We report a case of a postmenopausal woman with large ovarian calcifications secondary to a calcified corpus albicans imaged with sonography. A 64-year-old woman, gravida 2, para 2, with a medical history notable for ductal carcinoma in situ of the breast treated with a lumpectomy and radiation therapy was referred for endovaginal pelvic sonography before initiation of tamoxifen therapy. The patient had taken hormonal replacement therapy for 2 years during early menopause between ages 53 and 55 years and had a family history of

Sonographic Evaluation of Complications of Extracranial Carotid Artery Interventions

Carotid endarterectomy and carotid artery stenting are among the most common peripheral vascular procedures performed worldwide. Sonography is the initial and often only imaging modality used in the evaluation of iatrogenic carotid arterial injuries. This pictorial essay provides an overview of the clinical and sonographic findings of complications after interventions in the extracranial carotid arteries, including dissection, fluid collections, pseudoaneurysm, thrombosis, thromboembolism, restenosis, and stent deformation. Grayscale, color, and pulsed Doppler imaging findings are reviewed, and correlations with computed tomography, magnetic resonance imaging, and angiography are provided.

Computer-assisted detection of tardus parvus waveforms on Doppler ultrasound:

Objective To determine if a novel computer-generated metric, effective acceleration time, improves accuracy for detecting tardus parvus waveforms on spectral Doppler ultrasound. Methods Patients with echocardiography-confirmed aortic valve stenosis (n = 132; 60 mild, 44 moderate, 28 severe) and matched controls (n = 48) who underwent carotid Doppler ultrasound were identified through an imaging database search at a single medical center. A custom-built spectral analysis computer program generated effective acceleration time values for spectral Doppler waveforms in the carotid arteries and a receiver operating characteristic analysis was performed to determine the optimal median effective acceleration time cutoff value to detect tardus parvus waveforms. Two radiologists, blinded to subject disease status, reviewed and rated all carotid sonograms for presence of tardus parvus waveforms. Inter-rater variability was measured, and the accuracy of aortic valve stenosis detection with and without use of the effective acceleration time cutoff was calculated. Results Receiver operating characteristic analysis revealed an optimal effective acceleration time cutoff of ≥ 48 ms with a corresponding area under the curve of 0.77 (95% CI: 0.70–0.84). Use of the effAT cutoff demonstrated an accuracy of 74%. Accuracy of visual waveform interpretation by raters ranged from 43% to 61%. Inter-rater agreement in detection of tardus parvus waveforms was 76% (136/180 cases, K = 0.44, p < 0.001). Conclusions Detection of tardus parvus waveforms through visual interpretation of spectral Doppler waveform morphology is limited by low accuracy and moderate inter-rater variability. Use of a computer-generated median effective acceleration time cutoff value markedly improves diagnostic accuracy and avoids observer variability.

SPECT/CT in the Evaluation of Frostbite

Frostbite remains a challenging clinical scenario with multiple treatment algorithms and variable results. Currently, frostbite management often follows a conservative approach with rewarming followed by wound care and delayed amputation. We review seven patients where single-photon emission computed tomography (SPECT) fused with conventional computed tomography was used to evaluate tissue viability for earlier directed debridement and limb salvage. The goal of this report is to evaluate SPECT/CT as an appropriate modality for the screening of necrotic bone for earlier amputation in patients with frostbite. We retrospectively analyzed the records of seven patients (19 extremities) with frostbite who received SPECT/CT scans to evaluate deep tissue necrosis before digit amputation. All patients who presented within the first 24 hr following their injury without contraindications were initially treated with tissue plasminogen activator. Three patients met criteria and were treated with tissue plasminogen activator. Of the seven patients analyzed, none required revision amputation beyond the level predicted on SPECT/CT scan. No patients had viable tissue distal to the most distal extent of bone perfusion. In six of the patients, the SPECT/CT scan led to more distal amputation with proximal debridement of soft tissues thus maintaining extremity length. Frostbite remains a challenging clinical scenario for which there are a wide number of clinical algorithms. SPECT/CT appears to be valuable in the evaluation of frostbite to determine the need for amputation. Fusion of the nuclear images with the CT allows for more exact delineation of the level of amputation than a bone scan alone.

Appearance of the epiglottis during upper airway sonography.

Sonography is increasingly being explored as a tool for evaluation of upper airway anatomy and pathologic characteristics, with clinical use developing in areas as broad as the diagnosis of laryngeal and swallowing abnormalities, guidance for percutaneous tracheostomy and cricothyrotomy, prediction of difficult intubation and postextubation stridor, and measurement of epiglottal enlargement during acute epiglottitis.1–5 However, few studies have compared sonograms acquired for these purposes to those of wellestablished upper airway imaging modalities such as computed topography (CT) and magnetic resonance imaging. In some instances, such as in the identification of the epiglottis, the anatomy described in the ultrasound literature has failed to match images obtained by CT.6 The purpose of this report is to clarify and confirm the sonographic appearance of the epiglottis and to describe the surrounding anatomy as depicted on sonography. This process was done by identifying the normal epiglottis on CT and directly comparing it to sonography performed on the same patient at the same scanning angle. A 51-year-old man with a history of chronic submandibular sialolithiasis underwent postoperative head and neck CT with contrast after sialolithotomy. On the same day, midline oblique axial sonograms of the anterior neck were obtained midway between the inferior border of the hyoid bone and superior edge of the thyroid cartilage while the patient was supine with the head and neck in a neutral position (Figure 1A). Using the angle of the ultrasound transducer in relation to the mandible as a guide, a reformatted axial computed tomogram in the same oblique plane was generated (Figure 1, B and C). The appearances of the epiglottis, pre-epiglottic space, thyrohyoid membrane, strap muscles, thyrohyoid cartilage, and vestibular ligaments between imaging modalities were compared using measurements of structure depths and interstructural distances as guides for identification of anatomy. The established correct anatomy as identified on the computed tomogram was then used to confirm the correct correlative anatomy on the sonogram. The appearance of the adult epiglottis on sonography was first described by Böhme as “an echo free or echo-poor structure with a surrounding echogenic pre-epiglottic space.”7,8 Since this initial report, there have been several studies using these characteristics to identify the epiglottis without direct comparison to reference standard imaging modalities.3–5,8 However, in a recent study by Prasad et al,6 sonographic and CT measurements of several pharyngeal and hypopharyngeal airway parameters, including the depth of the epiglottis and thyrohyoid membrane, were compared in 15 adult patients with normal neck anatomy. On the basis of their measurements, the authors concluded that the pre-epiglottic fat appears hypoechoic and had been mislabeled as the epiglottis in previous studies using Böhme’s method of identification.7 Our case clarifies these inconsistencies and clearly distinguishes the epiglottis, pre-epiglottic space, thyrohyoid membrane, strap muscles, thyrohyoid cartilage, and vestibular ligaments on sonography through direct comparison to CT (Figure 1, A and B). The epiglottis, which is clearly seen on sonography as a thin hypoechoic structure bordered posteriorly by an echogenic air-mucosal interface, was measured at a depth of 25 mm from the skin versus 32 mm on CT. The difference in distances is likely secondary to skin and underlying fat compression by the ultrasound transducer. After adding the full thickness of the skin and fat as measured on CT (6 mm) to sonographic measurements of the epiglottic depth, the depths of the epiglottis on both modalities were equivalent (31 versus 32 mm). Furthermore, the relative distances between the epiglottis and its surrounding structures, which do not require corrective measures, were comparable between sonography and CT (epiglottis to vestibular ligaments, 12 versus 13 mm, respectively; epiglottis to thyrohyoid membrane, 16 versus 18 mm). It is important to note that the portion of the epiglottis visible on sonography is inferior to the vallecula and is not suspended in air because air would attenuate propagation of the ultrasonic signal. Other structures of the anterior hypopharynx are also easily matched between imaging modalities (Figure 1, A and B). On sonography, the pre-epiglottic space appears Clinical Letters