Skeletal muscle disease: patterns of MRI appearances.

Although the presumptive diagnosis of skeletal muscle disease (myopathy) may be made on the basis of clinical-radiological correlation in many cases, muscle biopsy remains the cornerstone of diagnosis. Myopathy is suspected when patients complain that the involved muscle is painful and tender, when they experience difficulty performing tasks that require muscle strength or when they develop various systemic manifestations. Because the cause of musculoskeletal pain may be difficult to determine clinically in many cases, MRI is increasingly utilised to assess the anatomical location, extent and severity of several pathological conditions affecting muscle. Infectious, inflammatory, traumatic, neurological, neoplastic and iatrogenic conditions can cause abnormal signal intensity on MRI. Although diverse, some diseases have similar MRI appearances, whereas others present distinct patterns of signal intensity abnormality. In general, alterations in muscle signal intensity fall into one of three cardinal patterns: muscle oedema, fatty infiltration and mass lesion. Because some of the muscular disorders may require medical or surgical treatment, correct diagnosis is essential. In this regard, MRI features, when correlated with clinical and laboratory findings as well as findings from other methods such as electromyography, may facilitate correct diagnosis. This article will review and illustrate the spectrum of MRI appearances in several primary and systemic disorders affecting muscle, both common and uncommon. The aim of this article is to provide radiologists and clinicians with a collective, yet succinct and useful, guide to a wide array of myopathies.

Intrahepatic venous continuation associated with inferior vena cava hypoplasia: evaluation with sonography, MR imaging and MR angiography.

A 17-year-old Asian girl was admitted to our hospital because of acute onset of abdominal pain. Abdominal imaging work-up revealed an unusual pattern of congenital vascular anomalies, including a hypoplastic IVC and large intrahepatic venous collaterals along with an atypical, accessory hepatic vein. Congenital or acquired abnormalities of the inferior vena cava (IVC) can lead to formation of collateral pathways that help bypass the blood flow obstacle.

Magnetic resonance imaging of para-acetabular insufficiency fractures in patients with malignancy.

AIM: To describe the characteristic magnetic resonance imaging (MRI) findings of para-acetabular insufficiency fractures in patients with malignancy, and compare the MRI appearance of these fractures with that of metastatic bone disease. MATERIALS AND METHODS: MRI examinations were reviewed in 16 patients with a known malignant tumour and severe hip pain that raised the possibility of local recurrence or metastatic disease. Six patients had received pelvic irradiation, and three patients were receiving steroid medication. RESULTS: The total number of fractures detected was 21: a solitary fracture was present in 11 patients and five patients had bilateral para-acetabular fractures. Two patients had associated sacral insufficiency fractures, and one of them had stress fractures involving both acetabular columns. Conventional radiography allowed the diagnosis of 14 (67%) fractures; six (28%) radiographic examinations were negative; and one (5%) examination was equivocal for fracture. Available scintigraphic and computed tomography (CT) studies revealed typical findings of fracture. Using MRI, insufficiency fractures appeared as linear regions of low signal intensity on T1- and T2-weighted images. Marked marrow oedema was evident in all cases. Fractures characteristically were parallel to the superior acetabulum in a curvilinear fashion in 18 (86%) instances, and were oblique in three (14%) instances. The fractures demonstrated considerable enhancement after intravenous gadolinium administration. No associated soft tissue masses were documented. CONCLUSION: Para-acetabular insufficiency fractures are a cause of hip pain, which may mimic skeletal metastasis in the patient with malignancy and pelvic irradiation. Recognition of the characteristic MRI findings of these fractures can preclude misdiagnosis and unnecessary bone biopsy.

MR imaging of uncommon recurrence of fibrolipomatous hamartoma of the ulnar nerve.

We present the MR and histopathologic findings of fibrolipomatous hamartoma (FLH) of the ulnar nerve in a 54-year-old woman, a lipomatous process that rarely affects the ulnar nerve. The case illustrated is further unusual as a local soft tissue recurrent mass developed over a remarkably long course of the disease.

Osteonecrosis of the patella: imaging features.

Osteonecrosis of the patella, although uncommon, has become important to recognize because it can be a cause of pain in the knee. We describe the imaging manifestations of nontraumatic osteonecrosis of the patella in seven clinical cases. The lesions uniformly involved the superior aspect of the patella. Conventional radiography displayed increased radiodensity, subchondral radiolucent areas, and typical demarcation line surrounding the ischemic region. MR imaging and bone scintigraphy demonstrated the characteristic features of osteonecrosis. Recognition of the imaging findings of osteonecrosis involving the patella can preclude misdiagnosis and may obviate unproductive invasive diagnostic procedures.

Calcium pyrophosphate dihydrate crystal deposition disease of the wrist: trapezioscaphoid joint abnormality.

OBJECTIVE: To determine whether trapezioscaphoid (TS) joint alterations are associated with calcium pyrophosphate dihydrate (CPPD) crystal deposition disease and, if so, to determine the nature of these alterations. METHODS: Radiographs of 160 wrists with evidence of chondrocalcinosis were evaluated with regard to TS joint abnormalities, and findings were compared with a similar number of radiographs in an age and sex matched control population in whom no evidence of chondrocalcinosis or other calcification in the wrist was seen. Two radiologists in consensus recorded radiographic findings in both groups, and a third radiologist blinded to the presence or absence of chondrocalcinosis reviewed wrist radiographs in both groups in a random order. Correlation of TS joint abnormalities with other changes in the wrist was also accomplished. RESULTS; TS arthropathy was found in 43.7% of CPPD wrists and in 14.4% of control wrists in the consensus evaluation. In the blind evaluation, 30% of CPPD wrists and 12.5% of control wrists had TS arthropathy. The degree of arthropathy was more extensive in the CPPD group than in the control group. Features associated with TS arthropathy in the patient population were first carpometacarpal arthropathy and subchondral cysts in the scaphoid or trapezium, or both bones. CONCLUSION: CPPD patients, compared to a control population, reveal frequent and significant radiographic abnormalities of the TS joint that may be suggestive of the diagnosis, even in patients in whom chondrocalcinosis is obscured or absent. The features associated with TS arthropathy are first carpometacarpal arthropathy and subchondral cysts in the scaphoid and trapezium.

Plantar fasciitis and fascial rupture: MR imaging findings in 26 patients supplemented with anatomic data in cadavers.

Understanding of the normal anatomy of the plantar aponeurosis (PA) and familiarity with pathologic conditions are required for an accurate evaluation of the patient with subcalcaneal heel pain. In this study, we evaluated the diagnostic capabilities of magnetic resonance (MR) imaging in the assessment of the PA with close anatomic correlation. Herein, we describe the MR imaging features of plantar fasciitis and fascial rupture in 26 patients. High-spatial-resolution MR imaging was performed in four cadaveric feet, and a prescribed imaging plane was used for depiction of the peroneal component of the PA. MR imaging delineated the anatomy of the PA and perifascial soft tissues. The peroneal component was best visualized in prescribed sagittal oblique images. Perifascial edema was the most common finding of plantar fasciitis, and it was remarkable in those cases with acute fascial rupture. MR imaging reliably delineated the anatomy of the PA and may allow precise localization and definition of the extent of involvement in disease processes.

Calcium pyrophosphate dihydrate crystal deposition in and around the atlantoaxial joint: association with type 2 odontoid fractures in nine patients.

PURPOSE: To investigate the histopathologic anatomy of calcium pyrophosphate dihydrate (CPPD) crystal deposition in and around the atlantoaxial joint and the association between CPPD crystal deposition and subchondral cysts, erosions, and fracture involving the odontoid process of the axis. MATERIALS AND METHODS: One adult cadaver demonstrating calcification in the retro-odontoid area at computed tomography (CT) was selected for further radiography, CT, and magnetic resonance (MR) imaging at the C1-2 level. Anatomic sectioning and histologic evaluations were performed in the specimen. For clinical study, radiographs (n = 5), CT scans (n = 8), and MR images (n = 6) in nine patients (mean age, 74.4 years) with odontoid process fractures and CPPD crystal deposits in and around the atlantoaxial joint were reviewed. RESULTS: In the cadaveric specimen, radiography and CT demonstrated calcifications in the transverse ligament; histologic evaluation confirmed that these calcifications were CPPD crystal deposits. In all nine patients, radiography (n = 5) and CT (n = 8) also showed calcification in areas adjacent to the odontoid process, which included the transverse ligament. T1- and T2-weighted MR imaging showed a retro-odontoid mass of low signal intensity that compressed the cervical cord in six patients. CT, MR imaging, or both demonstrated subchondral cysts, osseous erosions, or a type 2 odontoid fracture in all patients. CONCLUSION: CPPD crystal deposition disease involving the C1-C2 articulation can be a clinically important entity that may place affected patients at increased risk of pathologic fracture of the odontoid process.

Stress fractures of the lateral metatarsal bones in metatarsus adductus foot deformity: a previously unrecognized association.

OBJECTIVE: To document a distinctive pattern of stress fractures in the lateral metatarsal bones of patients with metatarsus adductus foot deformity. DESIGN AND PATIENTS: Conventional radiographs and available medical records were reviewed in 11 patients (6 women, 5 men; ages 25-61 years) with stress fractures of the lateral (fourth or fifth) metatarsal bones and metatarsus adductus. Evaluation included the number and location of fracture(s), forefoot adduction angle, and qualitative assessment of bone mineral density. Conditions that might predispose patients to metatarsal fractures, including direct trauma, osteoporosis, and neuropathic osteoarthropathy were also recorded. RESULTS: A total of 22 stress fractures were demonstrated, 17 of which involved the lateral metatarsals. A solitary fracture was present in six patients, while multiple fractures were evident in five patients. The sites of involvement were the fifth metatarsal (n=10), fourth metatarsal (n=7), third metatarsal (n=3), second metatarsal (n=1), and first metatarsal (n=1) bones. The locations of the stress fractures were in the proximal one-third of the metatarsal bones in 19 instances (86%) and in the middle one-third in three instances (14%). Forefoot adduction angle measured between 21 degrees and 37 degrees (normal range 8 degrees -14 degrees). CONCLUSION: Patients with metatarsus adductus may be at increased risk for stress fractures involving the lateral metatarsal bones, likely owing to the presence of altered biomechanics that place greater loads across the lateral aspect of the foot.

Comparative study of MR myelography and conventional myelography in the diagnosis of lumbar spinal diseases.

The purpose of this study was to investigate the usefulness of magnetic resonance (MR) myelography by comparing it with conventional myelography. MR myelography was performed on 40 patients (24 men and 16 women; mean age, 44 years) with lumbar spinal diseases. MR myelography was imaged three-dimensionally by fast spin-echo technique with fat suppression and maximum intensity projection. We assessed both the ability to provide the images of nerve root sheaths and the similarity of the findings to conventional myelography. Satisfactory images of nerve root sheaths in the lumbar region were provided almost equally by MR and conventional myelography. The images obtained by MR myelography were similar in quality to those obtained by conventional myelography. When combined with some other conventional MR imaging techniques, this diagnostic technique of imaging lumbar spinal diseases is further enhanced.

Gallbladder abnormalities associated with hypoplasia of the right lobe of the liver.

PURPOSE: We investigated the gallbladder abnormalities associated with anomalous right hepatic lobes using US, CT, and/or MRI. MATERIALS AND METHODS: The patients, four men and four women, ranged in age from 15 to 91 years, with a mean age of 59.5 years. The right lobe was hypoplastic in seven patients and was completely absent in one patient. RESULTS: The gallbladder was normally positioned in two patients (infrahepatic) and was absent in two patients. The gallbladder was located posterior to the liver in one patient (retrohepatic) and was located below the right hemidiaphragm in two patients (suprahepatic). Gallstones were present in one patient with jaundice and epigastralgia. CONCLUSION: Anomalous position or agenesis of the gallbladder often accompanies hypoplasia of the right hepatic lobe. Gallbladder position could be a good indicator of right hepatic lobe anomaly.

Mesenteric plexiform neurofibroma associated with Recklinghausen's disease.

We present a rare case of plexiform neurofibroma involving the ileal mesentery of a 10-year-old boy with Recklinghausen's disease. MRI showed multiple ring-like structures in the masses on T2-weighted and contrast enhanced T1-weighted images. Probably these findings reflect enlarged peripheral nerves with myxoid degeneration. MRI is useful for the diagnosis of mesenteric plexiform neurofibroma because of this characteristic appearance.

Intrahepatic portal-hepatic venous shunts demonstrated by US, CT, and MR imaging.

PURPOSE: Radiological findings were investigated in 6 cases of intrahepatic portal-hepatic venous shunt (IPHVS) without chronic liver disease. MATERIAL AND METHODS: Six patients with IPHVS were examined using US, CT and MR imaging. US was performed in all patients and color Doppler imaging in 5 patients. CT was performed after i.v. bolus injection of contrast medium in 4 patients. MR imaging and MR angiography were performed in one patient. RESULTS: The shunt was present in the right lobe in 4 patients and in the left lobe in 2 patients. The shunts consisted of focally dilated or tubular vessels (1 aneurysmal) in 4 patients, and multiple small vessels in 2 patients. US revealed anechoic structures with various configurations at the shunt. Color Doppler imaging could detect blood flow in various directions in the shunt vessels in 5 patients. CT and MR images showed these abnormal vascular structures in the liver. MR angiography was also useful for evaluating the relationship between the portal and the hepatic veins. CONCLUSION: Color Doppler imaging was the best modality for evaluation of IPHVS.

Motion related artifacts in spin-echo MR imaging: effects of sequence parameters on image quality at 1.5 Tesla.

PURPOSE: The purpose of this study was to evaluate the effects of selected parameters in a conventional spin-echo MRI sequence on image quality in a phantom undergoing periodic motion. METHODS: Images of a composite oil/copper sulfate phantom moving in a 1.5 Tesla magnet were acquired. The CuSO4 ghost signal-to-noise ratio (SNR) and distances between corresponding points on the phantom image and adjacent ghosts were evaluated. RESULTS: Increasing time to repeat (TR) and number of acquisitions (NAq) improved image quality. Ghost SNR was near unity at TR = 500 msec and at NAq around 4. Increasing TR and NAq resulted in increased distance between images. The effects of field of view (FOV) and matrix size on image quality were relatively less significant. CONCLUSION: Increasing NAq appeared to have a comparatively greater effect on ghost SNR and image quality under our experimental conditions. However, the effect of increasing NAq on image quality appeared to be definite since a saturation point was reached after a particular NAq. Increasing NAq above this point resulted in a relatively smaller improvement in image quality.

Epithelial cyst of the gallbladder demonstrated by ultrasonography: case report.

We present a rare case of epithelial cyst of the gallbladder in a 71-year-old man. Abdominal ultrasonography revealed a small cystic structure adjacent to the gallbladder. The cyst wall was thin and smooth, and protruded into the lumen of the gallbladder. Histologically, the cyst had no communication with the lumen of the gallbladder. The cyst wall was composed of fibro-muscular fiber, and lined by a single layer of ciliated columnar epithelium. Epithelial cyst of the gallbladder should be included in the differential diagnosis when radiological studies show a cystic structure in or adjacent to the gallbladder.

Hypoplasia of the right hepatic lobe with ectopy of the gallbladder.

Two cases of hypoplasia of the right hepatic lobe with gallbladder ectopy, which were diagnosed by computed tomography, are reported here. In each patient, the left hepatic lobe was enlarged. The gallbladder was located in the inferior portion of the liver in one patient and immediately below the right hemidiaphragm in the other. No other anomalies complicated these two cases. It should be kept in mind that hepatic lobe anomalies may have associated ectopy of the gallbladder.

Discovertebral junction of the spine--a cadaveric study by spin-echo MR imaging.

To evaluate the MR appearance of the discovertebral junction (DVJ) of the spine, we examined 161 DVJs in 27 cadaveric spines using superconductive MR imaging. T1-, proton density-, and T2-weighted spin-echo imaging were used. With a small surface coil, higher resolution and more sharply defined contours of the DVJ were obtained than when using a head coil. Cortical bone had very low signal intensity in all sequences. Cartilaginous end-plate (CP) was of low to intermediate signal intensity on T1-weighted images, and of low signal intensity on proton density- and T2-weighted images. MR images were able to reveal the gross CP appearances, Schmorl's nodules, and adjacent bone marrow pathology. We conclude that MR imaging is valuable for assessing abnormalities of the DVJ.

Intraspinal gas associated with intestinal necrosis detected by CT.

We report the case of a 63-year-old woman with necrosis of the small intestine and intraspinal collections of gas, which were detected using computed tomography (CT). Abdominal CT revealed extensive collections of gas in the portal and mesenteric veins and within the intestinal walls. Gas radiolucencies were also noted in the epidural spaces of her spine. This gas was considered to have migrated from the pelvic venous system into the internal venous plexus of the spine. Intestinal necrosis should be included in the differential diagnosis of intraspinal gas collections during CT.