Computerized method for nonrigid MR-to-PET breast-image registration.

We have developed and tested a new simple computerized finite element method (FEM) approach to MR-to-PET nonrigid breast-image registration. The method requires five-nine fiducial skin markers (FSMs) visible in MRI and PET that need to be located in the same spots on the breast and two on the flanks during both scans. Patients need to be similarly positioned prone during MRI and PET scans. This is accomplished by means of a low gamma-ray attenuation breast coil replica used as the breast support during the PET scan. We demonstrate that, under such conditions, the observed FSM displacement vectors between MR and PET images, distributed piecewise linearly over the breast volume, produce a deformed FEM mesh that reasonably approximates nonrigid deformation of the breast tissue between the MRI and PET scans. This method, which does not require a biomechanical breast tissue model, is robust and fast. Contrary to other approaches utilizing voxel intensity-based similarity measures or surface matching, our method works for matching MR with pure molecular images (i.e. PET or SPECT only). Our method does not require a good initialization and would not be trapped by local minima during registration process. All processing including FSMs detection and matching, and mesh generation can be fully automated. We tested our method on MR and PET breast images acquired for 15 subjects. The procedure yielded good quality images with an average target registration error below 4mm (i.e. well below PET spatial resolution of 6-7 mm). Based on the results obtained for 15 subjects studied to date, we conclude that this is a very fast and a well-performing method for MR-to-PET breast-image nonrigid registration. Therefore, it is a promising approach in clinical practice. This method can be easily applied to nonrigid registration of MRI or CT of any type of soft-tissue images to their molecular counterparts such as obtained using PET and SPECT.

Abdominal fat distribution in pre- and postmenopausal women: The impact of physical activity, age, and menopausal status.

Age-related increases in total body fat have been reported, but the impact of menopause on abdominal fat distribution is still unclear. The purpose of this study was to determine the impact of menopausal status on abdominal fat distribution using magnetic resonance imaging (MRI). In addition, we investigated the influence of abdominal fat distribution on blood lipid profiles and leptin concentrations. Twenty-three premenopausal (PRE), 27 postmenopausal (POST), and 28 postmenopausal women on estrogen replacement therapy (ERT) had measurements of regional abdominal fat, blood lipids, and serum leptin concentrations. The women were matched for body mass index (BMI) and total body fat mass. Age and menopausal status were not found to be significant predictors of total abdominal fat, visceral fat, or subcutaneous fat, while physical activity was a significant predictor (P <.01) for total abdominal fat (R(2) =.16), visceral fat (R(2) =.32) and percent visceral fat (R(2) =.25). There was a trend for a greater visceral fat content in the POST women compared with the PRE women (2,495.0 +/- 228.4 v 1,770.4 +/- 240.8 cm(2), respectively, P =.06). The percent visceral abdominal fat was significantly lower (P <.05) in the premenopausal women than in either postmenopausal group (PRE, 23.2% +/- 1.7%; POST, 28.9% +/- 1.8%; ERT, 28.9% +/- 1.6%). Menopausal status and age did not influence any of the blood lipid values. Abdominal fat distribution was a significant predictor of cholesterol concentrations and the cholesterol/high-density lipoprotein-cholesterol (HDL-C) ratio, but only accounted for approximately 15% of the variability in these levels. Total body fat and physical activity accounted for 47% of the variability in leptin concentrations, while abdominal fat distribution, age, and menopausal status were not significant predictors. In conclusion, in early postmenopausal women, the level of physical activity accounts for the variability in abdominal fat distribution observed, while menopausal status and age do not play a significant role. ERT was not associated with additional benefits in abdominal fat distribution compared with postmenopausal women not on ERT or in the blood lipid profile in these women.

An EM algorithm for estimating SPECT emission and transmission parameters from emissions data only.

A maximum-likelihood (ML) expectation-maximization (EM) algorithm (called EM-IntraSPECT) is presented for simultaneously estimating single photon emission computed tomography (SPECT) emission and attenuation parameters from emission data alone. The algorithm uses the activity within the patient as transmission tomography sources, with which attenuation coefficients can be estimated. For this initial study, EM-IntraSPECT was tested on computer-simulated attenuation and emission maps representing a simplified human thorax as well as on SPECT data obtained from a physical phantom. Two evaluations were performed. First, to corroborate the idea of reconstructing attenuation parameters from emission data, attenuation parameters (mu) were estimated with the emission intensities (lambda) fixed at their true values. Accurate reconstructions of attenuation parameters were obtained. Second, emission parameters lambda and attenuation parameters mu were simultaneously estimated from the emission data alone. In this case there was crosstalk between estimates of lambda and mu and final estimates of lambda and mu depended on initial values. Estimates degraded significantly as the support extended out farther from the body, and an explanation for this is proposed. In the EM-IntraSPECT reconstructed attenuation images, the lungs, spine, and soft tissue were readily distinguished and had approximately correct shapes and sizes. As compared with standard EM reconstruction assuming a fix uniform attenuation map, EM-IntraSPECT provided more uniform estimates of cardiac activity in the physical phantom study and in the simulation study with tight support, but less uniform estimates with a broad support. The new EM algorithm derived here has additional applications, including reconstructing emission and transmission projection data under a unified statistical model.

Familial encephalopathy with neuroserpin inclusion bodies.

We report on a new familial neurodegenerative disease with associated dementia that has presented clinically in the fifth decade, in both genders, and in each of several generations of a large family from New York State-a pattern of inheritance consistent with an autosomal dominant mode of transmission. A key pathological finding is the presence of neuronal inclusion bodies distributed throughout the gray matter of the cerebral cortex and in certain subcortical nuclei. These inclusions are distinct from any described previously and henceforth are identified as Collins bodies. The Collins bodies can be isolated by simple biochemical procedures and have a surprisingly simple composition; neuroserpin (a serine protease inhibitor) is their predominant component. An affinity-purified antibody against neuroserpin specifically labels the Collins bodies, confirming their chemical composition. Therefore, we propose a new disease entity-familial encephalopathy with neuroserpin inclusion bodies (FENIB). The conclusion that FENIB is a previously unrecognized neurodegenerative disease is supported by finding Collins bodies in a small kindred from Oregon with familial dementia who are unrelated to the New York family. The autosomal dominant inheritance strongly suggests that FENIB is caused by mutations in the neuroserpin gene, resulting in intracellular accumulation of the mutant protein.

Invasive aspergillosis diagnosed by fine-needle aspiration of the thyroid gland.

Invasive aspergillosis has been increasingly recognized as causing significant morbidity and mortality in immunocompromised patients but has never been diagnosed by fine-needle thyroid aspiration. A 24-year-old female with systemic lupus erythematosus presented with cough, shortness of breath, and fever of unknown origin unresponsive to broad-spectrum antibiotics. History and physical examination failed to indicate a source of infection. An 111In white blood cell scan showed thyroid localization. Physical examination revealed a multinodular goiter with a left dominant nodule. Fine-needle aspiration biopsy of a thyroid nodule revealed branching hyphae suggestive of Aspergillus sp. Despite immediate and aggressive treatment with amphotericin B and fluconazole, the patient died of overwhelming infection.

Familial dementia caused by polymerization of mutant neuroserpin.

Aberrant protein processing with tissue deposition is associated with many common neurodegenerative disorders; however, the complex interplay of genetic and environmental factors has made it difficult to decipher the sequence of events linking protein aggregation with clinical disease. Substantial progress has been made toward understanding the pathophysiology of prototypical conformational diseases and protein polymerization in the superfamily of serine proteinase inhibitors (serpins). Here we describe a new disease, familial encephalopathy with neuroserpin inclusion bodies, characterized clinically as an autosomal dominantly inherited dementia, histologically by unique neuronal inclusion bodies and biochemically by polymers of the neuron-specific serpin, neuroserpin. We report the cosegregation of point mutations in the neuroserpin gene (PI12) with the disease in two families. The significance of one mutation, S49P, is evident from its homology to a previously described serpin mutations, whereas that of the other, S52R, is predicted by modelling of the serpin template. Our findings provide a molecular mechanism for a familial dementia and imply that inhibitors of protein polymerization may be effective therapies for this disorder and perhaps for other more common neurodegenerative diseases.

Liposuction fat-fillant implant for breast augmentation and reconstruction.

The perfect breast implant fillant material would have higher viscosity than water and would be autologous and harmless. We describe the confinement of liposuction fat in implants using the Lipovacutainer during a routine liposuction procedure. This collected fat is prepared inside the Lipovacutainer and is reinjected through a Lipomedia filling cannula into a leaf valve implant as the fillant in place of saline. The implants are used for bilateral augmentation mammoplasty and breast reconstruction procedures. Our six clinical cases have been monitored closely using mammography and MRI. These cases showed slow liquefaction without interference with mammography studies. We obtained excellent overall body contours. All complications were correctable and non-life-threatening and there was no capsule formation.

Bone marrow reconversion in adults who are smokers: MR Imaging findings.

OBJECTIVE: Conversion of bone marrow in the extremities from red to yellow is a normal maturation process. Marrow reconversion is present when expected yellow marrow is replaced with active red marrow, and it tends to occur at times of physiologic stress. The significance of this finding on MR imaging is not always clear. Accordingly, we studied the prevalence of bone marrow reconversion in adults undergoing MR imaging of the knee for reasons other than marrow disorders. Possible relationships between marrow reconversion and age, sex, weight, and smoking were sought. MATERIALS AND METHODS: Fifty-nine outpatients over 24 years of age who had no evidence of hematopoietic disorders and for whom MR images of the knee were available for review were selected for study. Patients younger than 25 years old were eliminated to ensure that all patients in the study were old enough to have achieved normal adult marrow conversion. The 59 subjects were classified according to their smoking histories. Twenty-eight were nonsmokers, 10 were intermediate smokers, and 21 were heavy smokers. The MR images were classified as showing either red marrow (reconverted from yellow to red) or yellow marrow (converted) by two independent observers who had no knowledge of the patients' smoking histories. RESULTS: MR images of six heavy smokers, two intermediate smokers, and one nonsmoker showed evidence of reconversion. A statistically significant association between marrow reconversion and heavy smoking (p = .02) was found. Reconversion also was found to be more prevalent in patients less than 39 years old and in obese women who smoked. No association was found between weight, sex, or obese male smokers and reconversion. CONCLUSION: Our results show marrow reconversion at the knee is most prevalent in heavy smokers, younger patients, and especially obese women who smoke heavily. In these patients, marrow reconversion can be a normal finding on MR imaging. In other patients, other causes should be considered.

Generation of parametric images during routine Tc-99m PYP inhalation/Tc-99m MAA perfusion lung scintigraphy. Technical note.

A simple technique is described for generating ventilation/perfusion ratio and perfusion/ventilation ratio images from the posterior Tc-99m PYP aerosol inhalation and Tc-99m MAA perfusion images obtained during routine lung scintigraphy. These images highlight areas of ventilation/perfusion incongruence--mismatch or reverse mismatch--that may sometimes be difficult to detect on conventional images.

Atypical appearance of lipomatous tumors on MR images: high signal intensity with fat-suppression STIR sequences.

Lipomatous tumors generally have signal characteristics that allow them to be diagnosed with great accuracy by means of magnetic resonance imaging. These tumors usually have signal intensities similar to those of subcutaneous fat on both T1- and T2-weighted spin-echo images. Previous reports have not, to the authors' knowledge, described the appearance of lipomatous tumors on images obtained with a short-inversion-time inversion-recovery (STIR) sequence, which can be used to suppress signal from fat. Three lipomatous tumors (two liposarcomas and one lipoma) with signal characteristics unlike those of normal subcutaneous fat at all pulse sequences are presented.

Quantitation of abnormal 67Ga uptake in pulmonary interstitial vascular disease--a new test to detect diffuse lung disease.

Gallium 67 has been used as a modality to diagnose and follow the clinical course of diseases such as tumors, infections, inflammatory disorders, and interstitial lung disease. It has been appreciated, however, that mild to moderate changes in scan activity, when these disorders are followed over time, are less than optimal. SPECT (single-photon emission computed tomography) scanning is a new technique designed to obviate this problem. SPECT scanning utilizes computer acquisition to provide three-dimensional scanning and the additional benefit of colorization to aid in discerning differences of uptake. SPECT scanning was performed on 22 patients with interstitial lung disease of various etiologies. Additionally, 7 patients had follow-up SPECT scanning to determine their response to treatment. Two patients are presented as examples.

Multiplane gallium tomography in assessment of occupational chest diseases.

Gallium-67 scintigraphy is helpful in the evaluation of inflammatory, respiratory diseases. Single-photon emission computed tomography (SPECT) provides three-dimensional tomographic reconstruction of radioisotope distribution in the body. The addition of SPECT to gallium-67 scanning in 27 patients demonstrated an improvement in the sensitivity for detecting the presence and extent of interstitial occupational lung disease. This technique may provide earlier detection of parenchymal lung changes than can the chest x-ray and planar scanning in some patients with asbestosis. Findings in six patients with asbestosis are reported.

Magnetic resonance imaging of a third trimester abdominal pregnancy.

Abdominal pregnancies are rare, representing 1% of all ectopic pregnancies. Early and accurate diagnosis is essential in order to avoid the serious complications associated with the condition, including catastrophic hemorrhage secondary to placental separation. The clinical presentation of abdominal pregnancy is extremely variable and physical examination by itself may be insufficient for diagnosis. Ultrasound (US) is currently the imaging method of choice for establishing gestational location, but sonographic interpretation may be difficult due to gas within the gastrointestinal tract and distorted pelvic anatomy. The use of magnetic resonance imaging (MRI) in obstetric diagnosis, including abdominal pregnancy, has been described. We report a case of an abdominal pregnancy of 32 wk gestation diagnosed by MRI.

Multimodality approach to osteonecrosis of the femoral head.

Treatment of osteonecrosis of the femoral head appears to be effective when the disease is identified and treated early. Forty-one patients were evaluated with prospective laboratory assessment, anteroposterior and frog-lateral roentgenograms of both hips, intraosseous pressure measurements (IOP), magnetic resonance imaging (MRI), and 99mTc methylene diphosphonate planar and single-photon emission computerized tomographic (SPECT) bone imaging. Pathologic specimens were obtained in most patients. Preradiographic disease was identified in 26 hips and 11 of these were asymptomatic. Fifteen clinically symptomatic hips had normal plain roentgenograms, but abnormal protocol studies. Evaluation of sensitivity, specificity, and predictive value (positive and negative), respectively, in diagnosing osteonecrosis of the femoral head revealed the following percentages: 83%, 83%, 96%, and 48% for planar bone scanning; 91%, 78%, 94%, and 70% for SPECT; 87%, 83%, 96%, and 55% for MRI; 80%, 60%, 95%, and 25% for IOP; and 88%, 100%, 100%, and 25% for core biopsy. (There were few true negatives, thus specificity values are approximations.) The identification of preradiographic stages is possible, but difficult. MRI appears appealing at present, particularly in identifying disease in asymptomatic hips. However, there is no definitive method for noninvasive diagnosis. Pathologic confirmation in early stages is difficult.

Gd-DISIDA--a potential contrast agent for magnetic resonance imaging of the hepatobiliary system.

Gadolinium (Gd) labeled diisopropyliminodiacetic acid (DISIDA) was prepared by mixing a Gd solution and a DISIDA solution in appropriate proportions and at controlled pH. Optimal complexation was obtained at a Gd:DISIDA molar ratio of 1:2.5 and the pH of the final solution was 7.3 to 7.5. The complex was found to be stable both in vitro and in vivo. Gd-DISIDA (12.5 mumol/kg) was injected into mice, and T1 and T2 relaxation times of various tissues were measured and compared with those of normal tissues. Only the T1 values of the blood and the liver markedly decreased after Gd-DISIDA administration and also the reduction in T1 values depended on the dose of Gd-DISIDA. Magnetic resonance imaging of the rabbit liver showed considerable contrast enhancement at 30 minutes after administration of 12.5 mumol/kg of Gd-DISIDA.

Radionuclide assessment of the natural heart ejection fraction before and after LVAD implantation.

Complete pressure unloading of the ventricles can preserve ischemically damaged myocardium. Most clinical left heart assist device (LVAD) systems used after ischemic injury of the heart apply atrial cannulation which does not ensure pressure unloading. In order to assess the effect of the implantation of an intracorporeal LVAD on the function of the natural heart, we determined the ejection fraction (EF) in four male Holstein calves (90-105 kg) before and after insertion of a Cleveland Clinic pneumatic LVAD. A gated blood pool scan was obtained with a gamma camera after injection of 40 mCi Tc-labelled albumin. The animals were restrained in a sling to avoid movement artifacts. All animals showed a drop of 65 +/- 12% to 42 +/- 14% EF in the first postoperative (p.o.) week. Left ventricular output did not maintain sufficient blood pressure as assessed by pump-off tests. Systolic blood pressure dropped from 122 +/- 6.5 mm Hg to 81 +/- 6 mm Hg without pump support on the morning of the first p.o. day. Apical coring and possible restrained heart movement by the implanted LVAD may lead to impaired myocardial function that renders the individual LVAD dependent until adaptative corrections take place.

Magnetic resonance imaging of musculoskeletal infections.

In summary, MRI has a high sensitivity for the detection of inflammatory disease involving the musculoskeletal system. Because of the usual anatomic pattern of involvement in the vertebral column, there is also a high specificity. In the appendicular skeleton and pelvis, it is unclear whether MRI can add to the sensitivity and specificity of radionuclide studies in uncomplicated cases of acute infection. However, it can be performed more rapidly and provides greater anatomic detail and delineation of the extent of marrow involvement than radionuclide studies. MRI can be used in both acute and chronic osteomyelitis to guide a diagnostic interventional test to the appropriate site. It is capable of excluding involvement of the medullary canal, and it is better than radionuclide studies for differentiating soft tissue infection with periostitis from osteomyelitis. It has only a limited role in the immediate postoperative period, and in the presence of metallic implants, an indium-labeled leukocyte scan may be more appropriate. Finally, it must be remembered that the current data base of MRI is small and that further refinement of its role in the evaluation of inflammatory processes will be forthcoming.