Peter J. MacMahon

Injectable Corticosteroid and Local Anesthetic Preparations: A Review for Radiologists

Corticosteroids and local anesthetics are some of the most commonly administered medications in radiology departments. These medications have marked variability in their formulations, which may increase their adverse event profile for specific procedures. In particular, certain corticosteroid preparations are associated with adverse central nervous system (CNS) sequelae. This is most likely due to distal embolization by particulate formulations. Nonparticulate steroid formulations are not associated with such events. Local anesthetics have severe CNS and cardiac adverse effects if injected intravascularly and have recently been associated with intraarticular chondrolysis if used in large doses. This review discusses these medications with particular emphasis on their established and postulated adverse effects. The administering radiologist should be aware of these potential effects and how best to reduce their occurrence.

Molecular and magnetic resonance imaging: The value of immunoliposomes

Molecular imaging has the potential to transform the field of diagnostic imaging through enabling far more detailed investigation and characterisation of disease processes than is currently possible. Magnetic resonance imaging (MRI) is capable of three-dimensional non-invasive imaging of opaque tissues at near cellular resolution. Among the imaging techniques available today, MRI has, perhaps, the greatest potential to exploit the possibilities that molecular imaging presents. Nanoparticles are the focus of intense research, due to a wide variety of potential applications in the biomedical, optical, and electronic fields. In this article we examine the progress made in the development of nanoparticles as targeted contrast agents for molecular magnetic resonance imaging. In particular, we will examine the potential of antibody-targeted liposomes (immunoliposomes) as vehicles for delivering MRI contrast agents to cellular biomarkers, thus enabling visualisation of structures and processes at the molecular level. We will address some of the challenges that must be faced by researchers in this field before the progress made in the laboratory can be translated into improved clinical diagnostics and therapeutics.

MR Imaging of Muscle Injury

Although most muscle injuries in the athlete are diagnosed clinically, MR imaging is an excellent noninvasive diagnostic adjunct to clinical examination, which allows the site and severity of muscle injury to be assessed accurately, influencing therapy and overall outcome. There has been a rapid expansion in the clinical use of MR imaging during the past decade. MR imaging conveys unparalleled anatomic resolution and high sensitivity in the detection of acute and chronic muscle abnormalities. This article discusses the spectrum of muscle injuries, emphasizing the important role of MR imaging in their diagnosis and management.

Modified Prostate Volume Algorithm Improves Transrectal US Volume Estimation in Men Presenting for Prostate Brachytherapy

PURPOSE To evaluate the accuracy of the conventional transrectal ultrasonographic (US) prostate volume formula and determine whether a more accurate volume formula, calculated on the basis of prostate shape as observed at planimetry, can be described for the majority of prostate glands. MATERIALS AND METHODS This retrospective study was institutional review board approved, with waiver of informed consent. A total of 138 consecutive patients who underwent prostate brachytherapy were included for analysis. Prostate volume was estimated by using the conventional prolate ellipsoid formula (length x height x width x [pi/6]). A reference standard for prostate volume was calculated by using planimetry. The mean prostate shape was assessed by using three-dimensional volume-rendering of the planimetric images. The prostate shapes were evaluated to determine the best-fit mathematic formula for accurate volume estimation. Statistical analyses were performed by using Pearson correlation, paired Student t test, Bland-Altman plots, and concordance correlation coefficient. RESULTS Planimetric data showed the majority of prostate glands to be more bullet-shaped than ellipsoid. Only 13.3% of volumes determined by using the conventional prolate ellipsoid formula were within 10% of the planimetric volume. The prolate ellipsoid formula underestimated volume by 17% on average (95% confidence interval: 14%, 19%). A mathematic formula representing a bullet shape (length x height x width x [pi/4.8]) was determined to best represent the majority of prostate glands presented for brachytherapy; 75% of volumes were within 10% of planimetric volume by using this formula. Concordance correlation coefficient increased from 0.87 to 0.95. Formula accuracy was particularly improved in prostate glands smaller than 55 cm(3) (P = .14). CONCLUSION A modified prostate volume formula that closely represents the shape of the prostate smaller than 55 cm(3) demonstrated improved volume measurement accuracy compared with the prolate ellipsoid formula used in men presenting for brachytherapy.

MR Imaging of Overuse Injuries of the Hip

The aim of this article is to emphasize the importance of MR imaging in the evaluation of chronic hip pain and overuse injuries. Image interpretation of the hip can be difficult because of the complex anatomy and the varied pathology that athletes can present with, such as labral and cartilaginous injuries, surrounding soft tissue derangement involving muscles or tendons, and osseous abnormalities. The differential diagnosis in adults is diverse and includes such common entities as stress fracture, avulsive injuries, snapping-hip syndrome, iliopsoas bursitis, femoroacetabular impingement syndrome, tendinosis, and tears of the gluteal musculature.

MRI of injuries to the first interosseous cuneometatarsal (Lisfranc) ligament

ObjectiveThe objective of this study was to assess the utility of MRI in diagnosing injury to the first interosseous cuneometatarsal (Lisfranc) ligament and to additionally determine the associated patterns of traumatic soft tissue and osseous injury.Materials and methodsFifteen patients (16 feet) who were referred for MRI evaluation of the Lisfranc ligament, and had operative exploration or examination under anesthesia, were included for analysis. Standard non-contrast MRI foot imaging was performed in all cases. Evaluation of the following components was performed: the dorsal and plantar bundles of the Lisfranc ligament, the plantar tarsal metatarsal ligaments, soft tissue edema and fluid, and bone marrow edema and fractures. Surgical reports were regarded as the reference standard in all cases.ResultsSeven of 10 cases of grade 3 Lisfranc ligament injuries at surgery were correctly graded at MRI. No cases of surgically proven complete Lisfranc ligament tears (grade 3) were interpreted as normal at MRI. All Lisfranc ligament sprains (grade 2 or 3) at surgery were detected at MRI. Two of six cases reported as grade 1 injuries at MRI were normal at surgery. No cases of surgically proven normal or sprained Lisfranc ligaments were interpreted as grade 3 tears on MRI. Four of six of our cases of normal or sprained Lisfranc ligaments demonstrated fractures; while the minority of complete Lisfranc ligament tears (3/10) contained fractures.ConclusionMRI is reasonably accurate at detecting traumatic injury to the Lisfranc ligament. However, in clinically suspected cases of traumatic Lisfranc ligament injury, true positive rate for sprain is low.

Imaging of Groin Pain

Groin pain is a commonly encountered problem in musculoskeletal radiology. The diagnosis can be difficult to establish, based on the complex interconnected anatomy at the pubic symphysis and surrounding structures. The differential diagnosis is therefore broad, and diagnostic imaging is crucial in reaching the correct diagnosis, thus allowing appropriate therapy to be instituted. This article reviews the relevant anatomy and differential diagnoses encountered in overuse injuries of the groin. The common mechanisms of injury, presenting symptoms, and imaging findings for each diagnosis are addressed.

Rotator cuff impingement: correlation between findings on MRI and outcome after fluoroscopically guided subacromial bursography and steroid injection.

OBJECTIVE The purpose of this study was to describe the use of fluoroscopically guided subacromial bursography in the management of rotator cuff impingement and to correlate clinical outcome with preprocedural MRI findings. MATERIALS AND METHODS Sixty-nine patients with clinically and MRI proven subacromial impingement referred for fluoroscopic subacromial bursography and steroid injection between January 2004 and January 2006 were included in the study. After contrast-enhanced bursography, each patient received an injection of 80 mg of methylprednisolone and 1-2 mL of 0.25% bupivacaine into the bursa. Outcome was determined retrospectively and classified as complete resolution of symptoms, partial resolution of symptoms, or no change. MRI findings of impingement were graded according to severity. Outcome was evaluated as complete resolution and as complete or partial resolution in relation to MRI findings, duration of symptoms, age, and sex. RESULTS Complete resolution of symptoms was recorded in 40 (58%) of the patients. Fifty-seven (83%) of the patients reported some relief of symptoms after a mean follow-up period of 6 months. Shorter duration of symptoms and minor-grade MRI findings were associated with complete resolution. Younger age and minor-grade MRI findings were associated with complete or partial resolution. CONCLUSION Imaging-guided subacromial steroid injection may be of benefit in the short-term management of clinically and MRI-proven subacromial impingement, with 83% of 69 patients reporting symptom relief at 6-month follow-up evaluation. Patients with shorter duration of symptoms and minor-grade MRI findings have improved outcome.

Role of positron emission tomography--computed tomography in head and neck cancer.

Head and neck squamous cell carcinoma (HNC) is the sixth most common cancer worldwide. In the United States, it accounts for approximately 2% of all cancers and 2% of cancer deaths. The introduction of integrated positron emission tomography and computed tomography (PET/CT) has revolutionized imaging by permitting improved and more accurate anatomic localization of functional abnormalities in the complex territory of the head and neck region, and PET/CT has become a standard clinical imaging modality in patients with HNC. The main indications for PET/CT in HNC are in pretherapy staging, detection of unknown primaries, and monitoring of therapy response or disease surveillance. Although PET/CT is a promising tool in diagnosis and surveillance of HNC, there is lack of consensus as to its use, accuracy, and implications for patient management. The existing literature on the role of PET/CT in the management of HNC is reviewed, and a summary of the current debate is provided. Second primary cancers are the main cause of death among HNC patients with early disease, and the presence of distant metastases greatly impairs the survival of patients with advanced HNC. Therefore, early detection of second primary and metastatic tumors is imperative for optimizing survival outcome. However, given the lack of randomized, prospective trials addressing the role of PET/CT after chemoradiotherapy, the ideal function of PET/CT in disease surveillance has yet to be defined.

A biomechanical approach to MRI of acute knee injuries.

OBJECTIVE MRI is routinely performed to evaluate acute complex knee injuries. This article will review the fundamental biomechanical forces underlying the most important and common injuries and correlate MRI findings with specific traumatic mechanisms. CONCLUSION MRI findings can reveal the traumatic mechanisms in many acute knee injuries. By applying a biomechanical approach in MRI interpretation, it is possible to use easily detected lesions, such as osseous contusion and ligament rupture, to predict subtle but important abnormalities that might otherwise be missed. This systematic focused analysis enables a more accurate and rapid interpretation of knee MR studies.