Michel De Maeseneer

Measuring Thyroid Gland Volume: Should We Change the Correction Factor?

OBJECTIVE In the assessment of thyroid volume with sonography (formula of an ellipsoid), a correction factor is used. Whereas previously 0.524 was used, the World Health Organization has recently changed (after the first review) this correction factor to 0.479. We compare volume measurement of the thyroid using different correction factors to automated volume measurement using MDCT, and we define an optimal correction factor in thyroid volume assessment. CONCLUSION Acceptable correction factors are situated in the range of 0.494-0.554. We propose a correction factor of 0.529 when using the ellipsoid formula.

Posterolateral supporting structures of the knee: findings on anatomic dissection, anatomic slices and MR images

Abstract. In this article we study the ligaments and tendons of the posterolateral corner of the knee by anatomic dissection, MR-anatomic correlation, and MR imaging. The posterolateral aspect of two fresh cadaveric knee specimens was dissected. The MR-anatomic correlation was performed in three other specimens. The MR images of 122 patients were reviewed and assessed for the visualization of different posterolateral structures. Anatomic dissection and MR-anatomic correlation demonstrated the lateral collateral, fabellofibular, and arcuate ligaments, as well as the biceps and popliteus tendons. On MR images of patients the lateral collateral ligament was depicted in all cases. The fabellofibular, arcuate, and popliteofibular ligaments were visualized in 33, 25, and 38% of patients, respectively. Magnetic resonance imaging allows a detailed appreciation of the posterolateral corner of the knee.

Assessment of the long head of the biceps tendon of the shoulder with 3T magnetic resonance arthrography and CT arthrography

We studied the assessment of proximal biceps tendon lesions including degeneration, tendon luxation, and partial and complete tendon tears with 3T MR arthrography and CT arthrography. Thirty-six patients who underwent both studies, as well as arthroscopy were included in the study. The images were randomized and blinded and independently reviewed by two musculoskeletal radiologists. The pooled sensitivity for lesion detection for CT arthrography was 31% and the specificity 95%. The pooled sensitivity for MR arthrography was 27% and the specificity 94%. There were no statistically significant differences between CT and MR. The interobserver agreement calculated with the kappa statistic was poor for CT and for MR. Both CT arthrography and MR arthrography perform poorly in the detection of biceps tendon pathology of the shoulder.

Ultrasound of the elbow with emphasis on detailed assessment of ligaments, tendons, and nerves

The high resolution and dynamic capability of ultrasound make it an excellent tool for assessment of superficial structures. The ligaments, tendons, and nerves about the elbow can be fully evaluated with ultrasound. The medial collateral ligament consists of an anterior and posterior band that can easily be identified. The lateral ligament complex consists of the radial collateral ligament, ulnar insertion of the annular ligament, and lateral ulnar collateral ligament, easily identified with specialized probe positioning. The lateral ulnar collateral ligament can best be seen in the cobra position. On ultrasound medial elbow tendons can be followed nearly up to their common insertion. The pronator teres, flexor carpi radialis, palmaris longus, and flexor digitorum superficialis can be identified. The laterally located brachioradialis and extensor carpi radialis longus insert on the supracondylar ridge. The other lateral tendons can be followed up to their common insertion on the lateral epicondyle. The extensor digitorum, extensor carpi radialis brevis, extensor digiti minimi, and extensor carpi ulnaris can be differentiated. The distal biceps tendon is commonly bifid. For a complete assessment of the distal biceps tendon specialized views are necessary. These include an anterior axial approach, medial and lateral approach, and cobra position. In the cubital tunnel the ulnar nerve is covered by the ligament of Osborne. Slightly more distally the ulnar nerve courses between the two heads of the flexor carpi ulnaris. An accessory muscle, the anconeus epitrochlearis can cover the ulnar nerve at the cubital tunnel, and is easily identified on ultrasound. The radial nerve divides in a superficial sensory branch and a deep motor branch. The motor branch, the posterior interosseous nerve, courses under the arcade of Frohse where it enters the supinator muscle. At the level of the dorsal wrist the posterior interosseous nerve is located at the deep aspect of the extensor tendons. The median nerve may be compressed at various sites, including the lacertus fibrosis, between the pronator teres heads, and the sublimis bridge. These compression sites can be identified with ultrasound.

Pulmonary Disease in Cystic Fibrosis: Assessment with Chest CT at Chest Radiography Dose Levels

PURPOSE To investigate a computed tomographic (CT) protocol with iterative reconstruction at conventional radiography dose levels for the assessment of structural lung abnormalities in patients with cystic fibrosis ( CF cystic fibrosis ). MATERIALS AND METHODS In this institutional review board-approved study, 38 patients with CF cystic fibrosis (age range, 6-58 years; 21 patients <18 years and 17 patients >18 years) underwent investigative CT (at minimal exposure settings combined with iterative reconstruction) as a replacement of yearly follow-up posteroanterior chest radiography. Verbal informed consent was obtained from all patients or their parents. CT images were randomized and rated independently by two radiologists with use of the Bhalla scoring system. In addition, mosaic perfusion was evaluated. As reference, the previous available conventional chest CT scan was used. Differences in Bhalla scores were assessed with the χ(2) test and intraclass correlation coefficients ( ICC intraclass correlation coefficient s). Radiation doses for CT and radiography were assessed for adults (>18 years) and children (<18 years) separately by using technical dose descriptors and estimated effective dose. Differences in dose were assessed with the Mann-Whitney U test. RESULTS The median effective dose for the investigative protocol was 0.04 mSv (95% confidence interval [ CI confidence interval ]: 0.034 mSv, 0.10 mSv) for children and 0.05 mSv (95% CI confidence interval : 0.04 mSv, 0.08 mSv) for adults. These doses were much lower than those with conventional CT (median: 0.52 mSv [95% CI confidence interval : 0.31 mSv, 3.90 mSv] for children and 1.12 mSv [95% CI confidence interval : 0.57 mSv, 3.15 mSv] for adults) and of the same order of magnitude as those for conventional radiography (median: 0.012 mSv [95% CI confidence interval : 0.006 mSv, 0.022 mSv] for children and 0.012 mSv [95% CI confidence interval : 0.005 mSv, 0.031 mSv] for adults). All images were rated at least as diagnostically acceptable. Very good agreement was found in overall Bhalla score ( ICC intraclass correlation coefficient , 0.96) with regard to the severity of bronchiectasis ( ICC intraclass correlation coefficient , 0.87) and sacculations and abscesses ( ICC intraclass correlation coefficient , 0.84). Interobserver agreement was excellent ( ICC intraclass correlation coefficient , 0.86-1). CONCLUSION For patients with CF cystic fibrosis , a dedicated chest CT protocol can replace the two yearly follow-up chest radiographic examinations without major dose penalty and with similar diagnostic quality compared with conventional CT.

Pathology of Extrinsic Ligaments: A Pictorial Essay

The role of the extrinsic ligaments, together with the intrinsic ligaments, appears to be much more important than previously thought in the setting of carpal stability. The anatomy and pathology of the extrinsic wrist ligaments is complex. Magnetic resonance imaging (MRI) with thin slices is essential for visualization. This article describes the pathological appearance of the extrinsic palmar and dorsal radiocarpal and ulnocarpal ligaments on MRI, correlated with arthroscopy (performed by two skilled hand surgeons), clinical findings, and follow-up. High-resolution MRI, especially using isotropic three-dimensional sequences with orthogonal multiplanar reconstructions on 3T MR systems, allows detailed depiction of many of the extrinsic ligaments affected in carpal injuries. Recognition of ligament abnormalities is improved by intra-articular or intravenous injection of contrast before the examination. Both techniques may help to determine the precise localization, size, and extent of dorsal and palmar radiocarpal and ulnocarpal ligament lesions. Further experience with these techniques is needed to define the place of MRI in the management of traumatic wrist injuries.

Ultrasound of the elbow: A systematic approach using bony landmarks

The use of bony landmarks can be helpful in performing an ultrasound study of the elbow. We discuss bony landmarks that can be used for evaluation of the common extensor tendon, ulnar collateral ligament and common flexor tendon, coronoid and olecranon fossa, ulnar nerve, and biceps tendon. We discuss bony landmarks for each of these structures.

Fibroma of the tendon sheath of the long head of the biceps tendon

Fibroma of the tendon sheath is a benign tumor that is less common than giant cell tumor of the tendon sheath. Both tumors may present as a painless, slowly enlarging mass. Radiological findings may be similar for both tumors. Histologically, fibroma of the tendon sheath lacks the hemosiderin-laden macrophages that are typical for giant cell tumor of the tendon sheath. We report on a 49-year-old woman with fibroma of the tendon sheath of the long head of the biceps tendon. In our case, on MR images, we observed band-like hypointense areas centrally in the tumor, mild patchy contrast enhancement, and most importantly, no decrease of signal intensity on gradient echo images. These characteristics reflected histological findings.

Distal biceps brachii

There has been a renewed interest in the recent literature with regard to the normal anatomy of the distal biceps tendon. Cadaveric studies have demonstrated that a large percentage of individuals have two independent muscle bellies, the short and the long head, with two distinct separate tendons attaching at the radial tuberosity. To avoid diagnostic errors that may have an impact on patient management in case of tendon injury, it is important to keep this anatomical variant in mind. Ultrasonography has been shown to be a useful imaging modality in the evaluation of disorders of the distal biceps brachii muscle and tendon. In this article, we review the relevant anatomy of the distal biceps brachii, the ultrasound technique with alternative approaches for optimum visualization of the distal tendon, and the most common pathologies in this region.

Ultrasound of the sural nerve: normal anatomy on cadaveric dissection and case series.

The sural nerve is a small sensory nerve innervating the lateral aspect of the ankle and foot. Clinical symptoms of pathology may present as atypical sensory changes in this region. We present the normal anatomy and ultrasound technique for examination of the sural nerve based on an anatomical dissection, as well as imaging in a normal volunteer. We also present a case series (n=10) of different conditions of the sural nerve that we encountered based on a review of interesting cases from 4 institutions. The pathological conditions included neuropathy related to stripping or venous laser surgery, compression by abscess, Lyme disease, nerve tumors, traumatic transsection, and encasement by fibrous plaque and edema. Ultrasound with its exquisite resolution is the preferred imaging method for examining the sural nerve in patients with unexplained sensory changes at the lateral aspect of the ankle and foot.