Additional value of hybrid SPECT/CT systems in neuroendocrine tumors, adrenal tumors, pheochromocytomas and paragangliomas

The aim of this review was to evaluate the potential advantages of SPECT/CT hybrid imaging in the management of neuroendocrine tumors, adrenal tumors, pheochromocytomas and paragangliomas. From the collected data, the superiority of fused images was observed as providing both functional/molecular and morphological imaging compared to planar imaging. This provided an improvement in diagnostic imaging, with significant advantages as regards: (1) precise locating of the lesions; (2) an improvement in characterization of the findings, resulting higher specificity, improved sensitivity, and overall greater accuracy, (3) additional anatomical information derived from the CT component; (4) CT-based attenuation correction and potential for volumetric dosimetry calculations, and (5) improvement on the impact on patient management (e.g. in better defining treatment plans, in shortening surgical operating times). It can be concluded that SPECT/CT hybrid imaging provides the nuclear medicine physician with a powerful imaging modality in comparison to planar imaging, providing essential information about the location of lesions, and high quality homogeneous images.

Comparison of 111In-[DTPA0]Octreotide Versus Non Carrier Added 177Lu- [DOTA0,Tyr3]-Octreotate Efficacy in Patients With GEP-NET Treated Intra-arterially for Liver Metastases

AIM

In patients with progressive, metastatic neuroendocrine tumors (NET), intra-arterial radionuclide infusions with high activities of In-[DTPA]-octreotide and more recently with non-carrier added (nca) Lu-[DOTA,Tyr]-octreotate have been performed with encouraging results. However, the affinity profiles (IC50) of these radiopeptides for human sst2 receptors are markedly different (In-[DTPA]-octreotide, 22 ± 3.6 nM and nca Lu-[DOTA,Tyr]-octreotate, 1.5 ± 4.0 nM). The total administered activity is determined by organ dose limits (kidneys and bone marrow), and our aim therefore was to compare and evaluate the therapeutic efficacy of both radiopeptides in metastatic NETs.

METHODS

Thirty patients with gastroenteropancreatic (GEP) somatostatin-positive NETs with liver metastases confirmed on biopsy and In-pentetreotide scan were included. They were treated with In-[DTPA]-octreotide (n = 17) or nca Lu-[DOTA,Tyr]-octreotate (n = 13). Blood samples were collected 2, 4, 8, and 24 hours postadministration to calculate residence time in blood and in red marrow. The maximum percentage uptake in organs and tumors was estimated by region of interest analysis, and tumor dosimetry calculations were performed using OLINDA/EXM/ 1.0 software.

RESULTS

ncaLu-[DOTA,Tyr3]-octreotate blood radioactivity, expressed as a percentage of the injected dose, was significantly lower than In-[DTPA]-octreotide (P < 0.05), as clearly depicted from the time-activity curves; the background-corrected tumor uptake was significantly higher than In-[DTPA]-octreotide but without any significant difference in other organs (spleen, kidneys, and liver).

CONCLUSIONS

Using Lu-[DOTA,Tyr]-octreotate, a 3-fold higher absorbed dose to tumor tissue was achieved compared with In-[DTPA] octreotide. Residence time of nca Lu-[DOTA,Tyr]-octreotate results in a significantly higher absorbed dose to bone marrow compared with In-[DTPA]-octreotide. However, a drawback of In-[DTPA]-octreotide therapy is that the number of administrations would need to be almost doubled to achieve an equal therapeutic outcome as compared with Lu-[DOTA,Tyr]-octreotate.

Complications in thyroid resurgery: a single institutional experience on 233 patients from a whole series of 4,752 homogeneously treated patients

The aim of this study was to examine a homogeneous, consecutive recent series of patients who underwent reoperation on the thyroid bed to assess the incidence of the complications commonly correlated with resurgery. We reviewed clinical charts of 233 patients who underwent resurgery taken from a total of 4,752 patients previously operated on for benign and malignant thyroid diseases from 2006 to 2010 by the same surgical team. We evaluated the incidence of postoperative hemorrhage, hypoparathyroidism, and recurrent laryngeal nerve (RLN) palsy. Analyses were done separately in relation to the type of the type of resurgery adopted: (A) monolateral completion; (B) bilateral completion, after monolateral (B1) or bilateral prior surgery (B2); and (C) lymph node dissection. We also separately analyzed patients according to their final histological diagnosis of benign or malignant disease. Regarding hemorrhage, 6/233 patients (2.5 %) underwent surgical revision of the thyroid within 12 h for postoperative hemorrhage. They included 2 (1.5 %) of the 129 monolateral reoperations (A), 3 (4 %) of the 74 bilateral reoperations (B), and 1 (3.3 %) of the 30 central dissections for nodal relapse (C). Transient and definitive postoperative hypoparathyroidism was recorded in 78 (36.4 %) and 7 (3.3 %) of the 214 eligible patients. Transient RLN palsy occurred in 21 RLNs at risk (7 %) and definitive RLN palsy in 5 (1.7 %). Elective total thyroidectomy cannot always be supported as an effective policy for preventing recurrences in patients with a single, benign node: lobectomy, preferably with extemporaneous histological examination, unquestionably represents the best minimal approach to thyroid resection.

Quantitative evaluation of the amount of delayed myocardial enhancement as a predictor of systolic dysfunction

30 patients with delayed contrast enhancement in patterns suggestive of myocardial infarctions were reviewed. Infarct mass was quantitatively measured using short axis images obtained in the delayed phase of gadopentetate administration. Left ventricular mass and ejection fraction were measured using short axis, steady state free precession images. A relationship is drawn between increased mass of infarction and decreased left ventricular ejection fraction. For each gram of infarct, there is a 0.5 % reduction in ejection fraction (EF = 50 - (0.48 x gm infarcted myocardium); r²= 0.49). For each % increase of infarcted myocardium, there is a 0.67 % reduction in ejection fraction (EF = 50 - (0.67 x percent of infarcted myocardium); r²= 0.39). Left ventricular ejection fraction correlates inversely with the mass of myocardium with delayed enhancement on cardiac MRI.

MRI of destructive achilles tendon rupture associated with skin ulceration

We present a case series of the MR findings of destructive tears of the Achilles tendon secondary to overlying soft tissue ulcerations.

Diagnosis of vertebral metastasis, epidural metastasis, and malignant spinal cord compression: are T(1)-weighted sagittal images sufficient?

The objective of this study was to determine whether T(1)-weighted sagittal images alone are adequate in the diagnosis of vertebral metastasis, epidural metastasis, and malignant spinal cord compression. Ninety-four complete magnetic resonance (MR) studies of the spinal column (a complete study consisting of T(1)-weighted sagittal images, T(2)-weighted sagittal images, and T(1)- and/or T(2)-weighted axial images) and 94 T(1)-weighted sagittal images alone (a subset of the complete studies) from 57 consecutive cancer patients over the last 2 years with clinically suspected cord compression were blindly and independently evaluated by four radiologists. The complete MR studies were used as the standard. Overall, the sensitivity of T(1)-weighted sagittal images alone to vertebral metastasis (87%) was statistically greater than cord compression (70%) (p = 0.05), and statistically greater than epidural metastasis (46%) (p </= 0.02). The specificity for cord compression (97%) was greater than the specificity for epidural metastasis (89%) (p = 0.03), and greater than the specificity for vertebral metastasis (83%) (p </= 0.02). There was a strong trend for better detection of cord compression overall and better detection of vertebral metastasis in the cervical spine by the most experienced radiologist. Complete studies of the spine are necessary in the diagnosis of vertebral metastasis, epidural metastasis, and cord compression, particularly with less experienced radiologists.

Injury of the posterior ligament complex in patients with acute spinal trauma: evaluation by MR imaging

OBJECTIVE

We undertook this study to use MR imaging to determine the frequency of injury to the posterior ligament complex of the thoracolumbar spine in patients who have undergone acute thoracolumbar trauma.

SUBJECTS AND METHODS

Sixty-eight patients with varying severity of thoracolumbar trauma were examined prospectively. The majority of injuries were related to motor vehicle accidents. The second most common cause was falls. Patients were examined with plain radiography and MR imaging. In addition to conventional MR imaging sequences consisting of T1-weighted and fast spin-echo T2-weighted sagittal and axial images, a fat-suppressed T2-weighted sagittal sequence was performed. The findings were correlated with surgery in six cases and with follow-up clinical examination that included physical examination and conventional anteroposterior and lateral radiographs.

RESULTS

Posterior ligament complex injury was detected in 53% (n = 36) of all patients. Such injury was most common in patients with flexion-distraction (n = 15) and patients with dislocation fracture (n = 4). Of the patients with dislocation fracture, all had posterior ligament complex injury. Of the 24 patients with burst fractures, posterior ligament complex tear occurred in 42% (n = 10). Of the 23 patients with compression fractures, 26% (n = 6) had posterior ligament complex tear. Injury to the interspinous ligaments occurred with decreasing frequency in patients with injury to the supraspinous ligament, flaval ligaments, posterior longitudinal ligament, and anterior longitudinal ligament. Surgical findings correlated with MR imaging in all six patients who underwent surgery.

CONCLUSION

Injury to the posterior ligament complex, which is often encountered in patients with burst and compression fractures, can be reliably revealed by MR imaging.

Computer-assisted imaging of the fetus with magnetic resonance imaging

The purpose of this paper is to review the use of magnetic resonance imaging (MRI) of the fetus and to propose future techniques and applications. Institutional review board approved MR images of the fetus were acquired in 66 patients with sonographically suspected fetal abnormalities. Axial, coronal, and sagittal short TR, short TE images were obtained. In addition, 12 studies were performed with rapid scans requiring 700-1200 ms using either GRASS or Spoiled GRASS techniques. Sequential studies demonstrating fetal motion were also performed. Three studies with 3D IR prepped GRASS were performed. These allowed for orthogonal and non-orthogonal reformatted views and 3D display. Normal fetal structures were shown with MRI, including brain, heart, liver, stomach, intestines, and bladder. Gross fetal anomalies could generally be demonstrated with MRI. MRI may give additional information to that of sonography in fetal anomalies, particularly those involving the central nervous system, and in the detection of fat, blood, and meconium. MRI of the fetus can demonstrate normal and abnormal structures. Newer techniques with faster imaging will allow for greater possibility of computer assisted manipulation of data.

Radiologic studies in acute fatty liver of pregnancy. A review of the literature and 19 new cases

OBJECTIVE

Radiologic findings thought to be characteristic of acute fatty liver of pregnancy have been described in a limited number of cases. We describe wide experience with liver imaging of this disease.

STUDY DESIGN

A retrospective review was performed on charts from 1982 to 1994 to identify those patients with acute fatty liver of pregnancy who had radiologic studies.

RESULTS

Twenty-eight patients with acute fatty liver of pregnancy were identified, for an incidence of 1/6,692 births. Nineteen patients underwent at least one imaging study, and seven had more than one. Findings consistent with fatty infiltration of the liver are found in 3/11 patients with ultrasound, 5/10 with computed tomography (CT) and 0/5 with magnetic resonance imaging (MRI). Three patients with normal ultrasound scans subsequently had evidence of fatty filtration on CT scan.

CONCLUSION

Detection of fat in the liver of patients with acute fatty liver of pregnancy with current imaging techniques is limited and did not contribute to the management of patients in this series. Further studies are necessary to define to role of MRI--in particular, spectroscopy.

Magnetic resonance angiography in neck masses

Carotid MR angiography has primarily been used to evaluate for stenotic lesions. We performed 2D time of flight MR angiography in 25 patients with palpable neck masses. There were 23 masses confirmed histologically. Two of the masses represented abnormal carotid arteries. Carotid deviation was seen in 23 of 25 (92%) of patients. Widening of the carotid bifurcation was identified in seven patients, including four carotid body tumors, one inflammatory mass, one benign salivary gland tumor, and one schwannoma. Increased vascularity was identified in one carotid body tumor and in one metastatic papillary carcinoma of the thyroid. MR angiography may be useful to demonstrate flow within vessels and represents a familiar imaging display for surgical planning. Splaying of the carotid bifurcation is useful in demonstrating carotid space lesions.

Magnetic resonance imaging applications to cardiac diagnosis

Applications of MRI to cardiac diagnosis have improved and expanded. Thus, while MRI was initially useful for demonstrating cardiac anatomy, congenital malformations, thrombi, and masses, current techniques can demonstrate cardiac function, including evaluation of valvular disease and cardiac shunts along with cardiac flow quantitation. Further refinements have led to the demonstration of coronary artery anatomy. In the future, a comprehensive cardiovascular evaluation may be available with MRI.

The application of magnetic resonance techniques to the evaluation of the patient with sickle-cell disease

Sickle-cell anemia presents unique challenges to the clinician who wishes to obtain important data regarding anatomic lesions and metabolic states without subjecting the patient to additional risks involving the imaging techniques. Two applications-magnetic resonance angiography and magnetic resonance spectroscopy-are described in this review.

Method for assessing cardiac function using magnetic resonance imaging

The authors sought to define a method to use magnetic resonance (MR) to assess cardiac function by obtaining short-axis images of the left ventricle (LV) in humans. Sagittal and axial scout1H MR images were used in the protocol. The long axis of the LV was defined in both planes using the mitral valve and left ventricular apex as references. Based on this double angulation, the acquisition planes were created for a series of parallel short-axis images extending from the base to the apex of the left ventricular cavity. Cardiac images acquired with a fast-field echo technique, six slices with 16-20 phases per RR interval, were analyzed, representing the initial 75-80% of the cardiac cycle. For each slice, the endocardial border of the left ventricular chamber was manually traced. Using Simpson's rule, the total LV volume at a given phase was determined, considering the traced area, thickness, and position in three-dimensional space of each of the six constituent slices. The calculated volumes were plotted against time, and the stroke volume, ejection fraction, and cardiac output were determined. These parameters are clinically significant indices of cardiac function. Accurate and useful estimates of LV function can be obtained using MRI according to this protocol.

The impact on treatment planning of MRI of the spine in patients suspected of vertebral metastasis: an efficacy study

The objective of this study was to determine the efficacy of spinal MRI in suspected spinal metastasis. The effect of spinal MRI on treatment planning choices (radiation, chemotherapy, steroids, or surgery) in 130 patients with suspected spinal metastatic involvement was evaluated. In a retrospective group of 100 patients, 47 (47%) had therapy changes associated with MR findings. Forty out of 78 (51%) of patients presenting with symptoms (back pain, weakness, paresthesia, or sphincter dysfunction) had MR associated therapy choices. Seven out of 22 (32%) of patients without spinal symptoms had therapy changes. Twelve out of 30 (40%) of patients evaluated prospectively had therapy choices directed by MR findings. Overall, 59 out of 130 (45%) of patients had therapy choices associated with findings in spinal MRI. MRI results influenced the addition or modification of radiation therapy treatment in 33% of the patients suspected of metastatic disease to the spine.

MR imaging of patients with type 1 Gaucher's disease: relationship between bone and visceral changes

OBJECTIVE

Because treatment is now available for patients with Gaucher's disease, methods of follow-up have become important in making treatment decisions. Bone abnormalities (infarct and avascular necrosis) tend to be irreversible while visceral volumes are not, suggesting that it may be useful to follow patients with visceral volume determinations. In order to do so, the relationship of one to the other must first be understood. The purpose of this paper is to determine the relationships between bone and visceral changes identified with MR imaging.

MATERIALS AND METHODS

Sixty-two consecutive patients from 1 to 78 years old with type 1 Gaucher's disease were studied by MR imaging. The examination consisted of two parts: T1-weighted MR images and gradient-echo coronal MR images of the hips and femurs, and axial breath-holding MR images of the abdomen that allowed measurement of hepatic and splenic volume. The bone changes were classified and were correlated with the liver and spleen volumes. Specific imaging features of the liver and spleen were noted and correlation sought.

RESULTS

A statistically significant difference in liver size was found between patients with and without avascular necrosis. A statistically significant correlation was also found between liver size and avascular necrosis. Patients with marrow changes classified as grade 2 or higher were significantly more likely to have avascular necrosis. Nineteen percent of patients had splenic nodules and 7% had hepatic nodules; however, there was no correlation between the nodules and bone changes.

CONCLUSION

MR imaging showed a statistical relationship between marrow changes, liver size, and avascular necrosis in patients with type 1 Gaucher's disease. Knowledge of this relationship may be used in dosage and treatment considerations in the follow-up and clinical management of these patients.

Parceling of mesial frontal motor areas during ideation and movement using functional magnetic resonance imaging at 1.5 tesla

Finger movement-related responses were identified in three discrete sites of mesial frontal cortex in 7 normal subjects using high resolution functional magnetic resonance imaging. During imagination of the same movements there was a differential response with rostral areas more active than caudal areas. Humans have multiple motor areas in mesial frontal cortex that subserve different functions in motor planning and execution.

Magnetic resonance imaging in pregnancy

MR imaging can be important to demonstrate nonpelvic, pelvic, and fetal abnormalities in the pregnant patient. New, faster techniques expand diagnostic capabilities. Although no convincing evidence for fetal injury has been demonstrated, a rational approach to MR imaging in pregnancy is proposed in this article.

MRI-derived ventricular volume curves for the assessment of left ventricular function

To assess the utility of double oblique, ECG-gated 1H magnetic resonance (MR) derived volume curves for assessing LV function, cardiac short axis images were acquired with a fast field echo technique. We applied this methodology to assess left ventricular function in three groups: normals, patients with left ventricular hypertrophy, and dilated cardiomyopathy. Six slices with 16-20 phases per RR interval were analyzed, representing the initial 75-80% of the cardiac cycle. For each slice, the endocardial border of the left ventricular (LV) chamber was manually traced. Using Simpson's rule, the total LV volume at a given phase was determined considering the traced area, thickness and position in three-dimensional space of each of the six constituent slices. The calculated volumes were plotted against time and the stroke volume, ejection fraction and cardiac output were determined. The volume vs time plots for the systolic and diastolic portions of the curve were individually fit to third degree polynomials using a least squares approximation. From the fit curves, the following data were extracted: the mean slope (dV/dT) during filling and emptying, and the time to 1/4, 1/3 and 1/2 filling and emptying. These parameters are valuable indices of the functional status of the myocardium; thus, accurate and useful estimates of LV function can be obtained using MRI derived volume curves in normal and abnormal states.

Morton neuroma: evaluation with MR imaging performed with contrast enhancement and fat suppression

PURPOSE

To evaluate clinically suspected Morton neuroma with contrast material-enhanced magnetic resonance (MR) images.

MATERIALS AND METHODS

Fifteen patients with clinically suspected Morton neuroma underwent examination with conventional T1- and T2-weighted MR imaging and a combination of fat suppression and administration of gadopentetate dimeglumine. A T1-weighted spectral presaturation with inversion recovery sequence was used for fat suppression.

RESULTS

In six patients, a tumor that conformed to the clinical findings was seen in the interdigital space; surgical findings in these patients correlated closely with the imaging findings in all patients. Patients without positive findings on MR images tended to have less typical clinical findings and received nonsurgical treatment. In all patients, the lesions were best depicted with the combination of contrast-enhanced imaging and fat suppression; conventional MR images either entirely failed to demonstrate the lesions or demonstrated the lesions less clearly.

CONCLUSION

In patients who need imaging confirmation of a clinically suspected Morton neuroma, the combination of fat suppression and contrast enhancement provides reliable high-contrast images.

Magnetic resonance angiography of the neck veins

Time of flight, reduced matrix (64 x 256) MR angiography of the neck veins was performed in four normal subjects and four patients with neck vein thrombosis, either from indwelling catheters (n = 3) or intravenous drug abuse (n = 1). In each case, satisfactory images were acquired. Typical examination times of 3-6 min were required. MR angiography of neck veins gives a unique display of venous anatomy, including collateral veins and occlusions.

Evaluation of suspected musculoskeletal neoplasms using 3D T2-weighted spectral presaturation with inversion recovery

This study evaluated the use of the Spectral presaturation with inversion recovery (SPIR) technique with T2-weighting in 43 pathologically proven cases of suspected musculoskeletal neoplasm. Both primary and secondary malignant neoplasms as well as benign neoplasms were studied. The MR features exhibited by this technique are discussed. The images were evaluated by two experienced MRI specialists and graded as to utility into one of four categories as compared to conventional T1- and T2-weighted sequences. In the majority of cases this technique was found to be helpful or extremely helpful. The most useful features of this technique were the elimination of chemical shift artifact, the improved ability to evaluate superficial lesions or the extension of lesions into subcutaneous fat, and substantially improved visualization of both bone marrow and bone cortex interfaces. T2-weighted, fat suppressed imaging proved to be a useful new tool for evaluating musculoskeletal neoplasms.

Giant extra-adrenal pheochromocytoma: magnetic resonance imaging with gadolinium-DTPA enhancement

A case report of a 35-yr-old male presenting with moderate hypertension and a giant extra-adrenal pheochromocytoma is discussed. The patient was treated by chemotherapy and surgery with regression of the lesion and clinical relief of symptoms. Initial magnetic resonance imaging (MRI) with gadolinium-DTPA enhancement revealed a large complex pelvic mass. Follow-up examination following chemotherapy three months later demonstrated partial regression. The MRI findings and the pattern of gadolinium-DTPA enhancement are discussed.

MRI of the brachial plexus: a review of 51 cases

We present a magnetic resonance imaging (MRI) study in 51 patients where the brachial plexus was evaluated. Using a 1.5 T clinical imaging system, we obtained T1-weighted sequences, and double-echo (intermediate- and T2-weighted) spin-echo images. The coronal plane was imaged in all examinations and was supplemented by images in the sagittal and/or axial planes. Twenty cases had proven pathological brachial plexus involvement, whereas, in 31 cases, no brachial plexus involvement was present. In 4 cases, the MRI findings were not in agreement with the final diagnosis found in the charts.

SPIR MRI in spinal diseases

We report on our experience with the fat suppression technique of spectral presaturation with inversion recovery MR in imaging certain spinal disorders. This technique may assist in demonstrating or excluding the presence of fat within a lesion (such as lipoma, dermoid, teratoma) or within a normal structure (i.e., vertebral body or epidural space). The method can also be used to suppress normal fat (such as marrow or epidural fat) thus increasing the conspicuity of adjacent high signal intensity lesions seen on T1-weighted images (such as blood and contrast-enhancing tumors or inflammatory lesions).

MR imaging in rhinocerebral and intracranial mucormycosis with CT and pathologic correlation

Three cases of mucormycosis, two in diabetics and one in an intravenous drug abuse patient, are presented. Magnetic resonance imaging proved to be useful in all cases, as was computed tomography. In one case, extremely low signal was detected from the fungal mass. It is surmised that this appearance was a result of high concentrations of iron and manganese. The low-signal area simulated air in paranasal sinuses; however, CT displayed a mildly enhancing soft tissue mass and allowed the correct diagnosis to be made. In another patient, pontine infarction was demonstrated by MR. In the third case the MR findings of mucormycosis involving the basal ganglia are shown and correlated with CT. Subsequent imaging studies demonstrated reduction of the mass, corresponding to clinical improvement.

Magnetic resonance of the inferior vena cava

MRI was performed in 54 patients with abnormalities of the inferior vena cava (IVC). These included 16 patients with extrinsic IVC compression, 32 patients with intrinsic IVC abnormalities, and 6 patients with IVC dilatation. All patients had spin-echo imaging, and 21 had MR angiography. While presaturated spin-echo images showed intrinsic lesions to advantage, collateral vessels were best appreciated with MR angiography. The IVC is well evaluated with MRI techniques.

Magnetic-resonance imaging used for determining fat distribution in obesity and diabetes

Computed-tomography scanning and magnetic-resonance imaging (MRI) have been used to quantify intraabdominal and subcutaneous fat depots. In this study MRI was used to define fat-distribution patterns in 24 obese females with non-insulin-dependent diabetes (NIDDM) and 12 females with simple obesity. Subjects had anthropometric measurements and single-slice abdominal scans performed at the umbilicus. In addition, in 10 of the nondiabetic females, measurements were repeated after 10 wk of a very-low-calorie diet. Nondiabetic females had significantly less intraabdominal fat (P less than 0.01) than did the diabetics but had equivalent subcutaneous fat. There was no significant relationship between waist-to-hip ratio and intraabdominal fat, subcutaneous fat, or their ratio. After a weight loss of 10.6 +/- 3.8 kg there were significant decreases in both intraabdominal and subcutaneous fat (P less than 0.01). Weight loss is associated with decreases in fat in both depots.

MR imaging of fetal anomalies

MR imaging can be used to confirm the presence of most gross fetal anomalies detected by sonography in the second and third trimesters. The MR imaging findings in 25 cases of fetal anomalies first identified on sonography are illustrated.

Cardiac MRI cine and color Doppler in valvular disease: correlative imaging

Cardiac cine field echo MRI and color Doppler were performed in 13 patients with aortic regurgitation (n = 4) or multiple valvular diseases (n = 9). The size, shape, and direction of regurgitation jets correlated well. Color Doppler was better able to follow flow jets in oblique planes. Cine MRI was better able to evaluate patients with marked cardiac dilatation.

Spinal MR imaging in suspected metastases: correlation with skeletal scintigraphy

Bone scintigraphy (RN) and magnetic resonance imaging (MR) were prospectively and retrospectively correlated in 64 patients with suspected spinal metastatic disease and possible spinal cord compression. Images were retrospectively interpreted and compared with the prospective official RN and MR reports to help decide relative prospective lesion conspicuity. Spinal lesions were confirmed by radiography, computed tomography, myelography or MR and RN follow-up in 56 patients (88%). Prospectively, MR detected 11 lesions not reported on RN while RN detected two lesions not reported on MR. Retrospective review of RN detected six lesions previously not reported. Retrospectively MR showed all lesions. Those lesions seen only in retrospect by RN were rather subtle and would be difficult to detect prospectively. In general, lesions not well seen on RN had relatively more bone marrow abnormality and less cortical bone involvement. In some cases, MR imaging shows spinal marrow lesions not well seen on planar RN.

Magnetic resonance imaging of a post-traumatic arteriovenous fistula in the lower extremity

Currently, magnetic resonance (MR) is most useful as a means of providing distinct images of gross abnormalities in major blood vessels. While new advances and further refinements will continue, MR has proven its value as a convenient and effective diagnostic tool for the recognition and delineation of vascular abnormalities, such as acquired arteriovenous fistulae (AVFs). We report a case of a chronic, post-traumatic AVF, in which MR angiography provided excellent anatomic detail and angiographic correlation.

Halfscan: clinical applications in MR imaging

A series of phantom experiments was performed to evaluate the effects of half-Fourier scanning, also known as Halfscan, on signal-to-noise and in-plane resolution. Resolution was not demonstrably effected with the available phantoms and signal-to-noise was seen to vary as the square root of time independent of the implementation of Halfscan. Evaluation of the Halfscan technique was made using data from 240 patients. The technique was found to "salvage" examination in an estimated 70% of uncooperative patients where motion artifact or other patient concerns would have precluded clinically useful studies. Halfscan was also combined with other techniques such as increased number of signal acquisitions, prolonged repetition times and three-dimensional Fourier transform technique.

Primary lymphoma of the cervix: MRI findings with gadolinium

MRI evaluation of primary cervical lymphoma has not been reported. We report such a case of primary cervical lymphoma, a lesion well seen and well delineated from normal tissue by MRI. Although primary lymphoma of the cervix is a rare entity, the disease does exist and can be well demonstrated by MRI. We evaluated the MR appearance of this lesion with both nonenhanced and gadolinium-enhanced imaging.

Cardiac calcifications: difficult MRI diagnosis

Magnetic resonance imaging (MRI) and computed tomography (CT) were performed in 40 patients with a variety of cardiovascular diseases. These imaging modalities were compared to investigate their relative value in the assessment of cardiovascular diseases. Of these 40 patients, 7 were found by CT to have detectable cardiovascular calcifications. These patients included one calcified mitral stenosis, one calcified coronary artery, one calcified type B aortic dissection, two calcified myocardial infarctions, and two patients with calcific pericarditis. In several cases, MRI was misleading because of difficulty in detecting calcifications. We present a series of cases illustrating a limitation of MRI in identifying diagnostically and clinically important cardiovascular calcifications.

Computed tomography in endobronchial neoplasms

Computed tomography (CT) was performed in 86 patients with bronchoscopically proven endobronchial neoplasms. There were 76 primary and 10 metastatic lesions. CT correctly identified the abnormal airway in 95% of cases (82/86) by demonstrating either nodule, mass, or stricture. A discrete endobronchial nodule was seen in 55% (47/86). There was good morphological correlation of CT with bronchoscopic findings (89% for discrete nodule, 80% overall). Appropriate atelectasis was noted in 80% (69/86) of cases. CT is sensitive in detecting and localizing endobronchial neoplasms and correlates well with bronchoscopic findings.

Metallic ballistic fragments: MR imaging safety and artifacts

The ferromagnetism of various bullets and shotgun pellets was tested in vitro. Magnetic deflection showed that four of 21 metallic specimens tested (all bullets) demonstrated marked ferromagnetism. Three of these four were made outside the United States; two of the four were known to contain steel, and the other two were reportedly either copper or copper-nickel-jacketed lead bullets (indicating that the ferromagnetism was due to impurities in the bullet jackets or cores). Ferromagnetic bullets readily rotated within a gelatin phantom in response to magnetic torque. Nonferromagnetic bullets and pellets demonstrated only mild to moderate metal artifact during spin-echo and gradient-echo magnetic resonance (MR) imaging. However, all four of the ferromagnetic bullets produced severe MR artifacts and image distortion. MR studies of seven patients with retained bullets, pellets, or shrapnel were reviewed. In six of the seven, only mild MR artifacts were seen. Only intracranial shrapnel (presumably steel) in one patient created significant artifact. All seven patients with retained bullets and shotgun pellets were imaged safely with MR. However, caution should be exercised with MR imaging in the presence of metallic foreign bodies, particularly if they are located near vital neural, vascular, or soft-tissue structures.

MRI evaluation of AIDS-related encephalopathy: toxoplasmosis vs. lymphoma

The spectrum of cranial MRI findings was evaluated in 113 patients with the acquired immunodeficiency syndrome, assessing lesion number, size, location, and configuration in association with the autopsy and/or biopsy results. Correlation of cranial MRI and CT was performed in 32 patients. MRI was shown to be superior in sensitivity of lesion detection demonstrating more lesions than CT in 14 studies (44%) and equivalent information in 18 studies (56%). In no case did CT demonstrate lesions not detected on MRI. We conclude that MRI should be the study of choice in evaluating AIDS-related encephalopathy. Multiple lesions that involve both deep gray matter and white matter suggest the possibility of CNS lymphoma. The "target" appearance on MRI is not helpful in distinguishing toxoplasmosis from lymphoma.

Magnetic resonance imaging features in melanoma

T1 and T2 relaxation time shortening secondary to paramagnetic compounds has been described in melanoma. The purpose of this paper is to evaluate the signal behavior of melanoma involved in various body areas using short TR, TE and long TR, TE sequences. Twenty-seven sites of melanoma were evaluated with MR using T1 weighted and T2-weighted techniques. Using fat and muscle signal intensities as references tissues, lesions were graded into high, low or intermediate intensity categories for each of the sequences. Four signal patterns emerged. The typical pattern characterized by high signal on T1-weighted images and low signal on T2-weighted images reflected T1 and T2 shortening. The other pattern categories comprised of lesions demonstrating low signal T1-weighted images and high signal on T2-weighted images, high signal on both T1- and T2-weighted images and lesions showing intermediate signal on either T1- or T2-weighted images. We observed a tendency away from the typical signal pattern in extraocular melanoma cases with only one of 14 demonstrating this pattern. Moreover, only seven of thirteen ocular melanomas exhibited such behavior. Possible explanations for this findings as well as the existence of a variety of MR appearances to melanoma are offered. We conclude that while signal patterns showing T1 and T2 shortening are typical of melanoma, the absence of these does not exclude the diagnosis.

Magnetic resonance imaging of nasopharyngeal and paranasal sinus melanoma

Malignant melanoma of the nasopharynx and paranasal sinuses is relatively rare. We retrospectively reviewed the magnetic resonance appearance of five cases and correlated this with the histopathological appearance. In all cases, the magnetic resonance (MR) images clearly demonstrated the precise anatomic extent of the tumor and were sensitive in assessing intracranial extension and invasion into surrounding structures, including the skull base. Three cases were reviewed for histopathological evidence of melanin, hemosiderin, and acute hemorrhage. One case was reviewed for melanin and hemorrhage only. The findings in this series suggest that melanoma of the nasopharynx and paranasal sinuses have extremely variable amounts of paramagnetic substances, both melanin and products of hemorrhage. T1 shortening appears to be more often a reflection of the paramagnetic effects associated with products of hemorrhage rather than the presence of melanin.

Magnetic resonance imaging and the severity of dementia in older adults

Periventricular white-matter lesions were visualized in the brains of elderly patients being assessed for possible Alzheimer's disease. The magnitude of these lesions, expressed as lesion-brain ratios, correlated closely with the severity of dementia indicated by scores on the Blessed Dementia Scale and the Folstein Mini-Mental State Examination. Impairment in several domains of cognitive functioning tested by the Mini-Mental State Examination was also correlated with the relative quantity of periventricular lesions. Correlations were significant with systolic blood pressure, approached significance with age, and were not significant with duration of dementia or the magnitude of the lateral ventricles. These findings indicate the potential utility of structure-function correlations that are possible with magnetic resonance imaging in identifying mechanisms underlying dementia. They suggest that magnetic resonance imaging may be more useful than computed tomography in following the course of dementia.

Demonstration of aortic lesions via cine magnetic resonance imaging

Cine-MRI was used to evaluate eight patients with known thoracic aorta disease. Included in this study were three aortic coarctations, two aortic dissections, an aneurysm, a posttraumatic pseudoaneurysm, and a patent ductus arteriosus. Cine-MRI was found to be valuable in the assessment of the pathologic anatomy and associated flow disturbances in these disorders. In seven cases, the images demonstrated the aortic lesion and aberrant blood flow. Our technique was unable to image the structural lesion in the patient with patent ductus arteriosus, but the abnormal blood flow was shown. Angiographic data were available on three of the cases to confirm the MR findings. The MRI images were obtained in axial, coronal, sagittal, and oblique planes using fast field echo acquisition technique of cine-MRI. We found the additional data or benefits provided by cine-MRI, when compared to cardiac gated spin echo images, to be most advantageous in the cases of aortic coarctation and dissection only.

MRI of the skull

Thirty-four patients with a wide variety of benign and malignant incidental skull findings on routine magnetic resonance (MR) imaging of the brain were reviewed. In most instances detection of the lesions was not difficult. However, recognition of various patterns of skull involvement in different disease processes is important. This is particularly true in differentiating benign from malignant lesions, which may be a critical factor in patient management.

Radionuclide angiography in suspected acute cholecystitis: further observations

Radionuclide angiography (RNA) and cholescintigraphy were performed prospectively in 300 patients with suspected acute cholecystitis (AC). Of 79 patients with positive RNA, 63 had AC (80%). Positive RNA was seen in 23 of 26 cases with gangrenous AC (88%) while 12 of the 26 had a positive "rim" sign (46%). All 12 patients with a positive "rim" sign had positive RNA. The "rim" sign may be caused by increased perfusion. Five of 6 patients with positive RNA and "obstructive" pattern had AC (83%). Patients with negative RNA and positive cholescintigraphy had a positive predictive value of 54% (31/57), while those with positive RNA and positive cholescintigraphy had a positive predictive value of 85% (57/67). RNA showed increased perfusion to nonbiliary pathology such as liver abscesses and pyelonephritis. Positive RNA increases the predictive value of cholescintigraphy and may be useful to shorten cholescintigraphic examinations.

Compression of pulmonary artery by syphilitic thoracic aortic aneurysm: imaging

A case of syphilitic aortitis with multiple thoracic aneurysms, one of which caused compression of the left pulmonary artery with hypoperfusion of the left lung as seen with perfusion scintigraphy, blood pool studies, CT, and magnetic resonance imaging is presented.