Mediastinal hibernoma simulates a malignant lesion on dual time point FDG imaging.

Dual time point 2-deoxy-2-[18F] fluoro-d-glucose (FDG) positron emission tomography (PET) imaging has been shown to be useful in helping differentiate benign from malignant lesions. An enhancing mediastinal mass of fat and water density was incidentally detected on computed tomography (CT) in a patient being evaluated for thoracic trauma. He subsequently underwent dual time point FDG PET/CT imaging which revealed a significant rise in standard uptake value (SUV) within the lesion over time, favoring a malignant etiology. Biopsy proved the lesion to represent a hibernoma, an uncommon benign fatty tumor. This case exemplifies the complexity of tissue metabolic properties, and the difficulty in establishing absolute criteria for benign and malignant processes.

Primary adrenal lymphoma: gallium scintigraphy and correlative imaging.

Primary adrenal lymphoma is a rare entity, with only 16 cases reported in the last 40 yr. Although 67Ga scintigraphy has been extensively used to evaluate patients with other types of lymphomas, there are no reports of its use in patients with this disease entity. A man with primary adrenal lymphoma and no evidence of extraadrenal spread who was evaluated from presentation to remission with gallium scintigraphy and CT is presented. Gallium scintigraphy was valuable in assessing response to therapy.

PET, CT, and MRI in the evaluation of neuropsychiatric disorders: current applications.

Positron emission tomography (PET) is emerging as a very useful clinical tool and is adding a great deal to our understanding of the pathophysiology of central nervous system (CNS) disorders. Although computed tomography (CT) and magnetic resonance imaging (MRI) have had a dramatic impact on patient management, there is often an important associated function abnormality which is best assessed by PET. In normal aging and in dementia, the CT and MRI brain changes of atrophy and white matter abnormalities are frequently nonspecific. PET has been more diagnostic, showing characteristic regional metabolic abnormalities. Evaluation of brain tumors such as astrocytomas with PET has demonstrated better correlation with histologic grade compared to CT. Unlike CT or MRI, PET can help to distinguish radiation necrosis from recurrent tumor, and can differentiate the extent of metabolically active tumor from surrounding edema. PET is useful in evaluating stroke patients, providing better prognostic information and demonstrating abnormalities sooner than CT. In epilepsy, PET appears to be superior to MRI in localizing seizure foci in patients with partial seizures. In head trauma patients, metabolic patterns are being described which will likely have an effect on patient management. The use of PET in schizophrenia has yielded very interesting results, with common patterns of metabolic abnormalities being demonstrated. CT and MRI in these patients have not been very useful. PET has also shown promise in movement disorders such as Huntington's disease. It is now clear that PET is already clinically useful and can provide valuable information unobtainable by CT and MRI. As new radioligands are developed, PET is certain to assume an even more important role in the future.

Regional metabolic alterations in Alzheimer's disease: an in vitro 1H NMR study of the hippocampus and cerebellum.

The concentrations of selected metabolites in the hippocampus and cerebellum of 13 Alzheimer's diseased (AD) and four nondemented postmortem brains were measured using high resolution 1H NMR spectroscopy. For both the hippocampal region and the cerebellum, the putative neuronal marker N-acetyl aspartate (NAA) was significantly lower in AD brains relative to the nondemented brains. For the hippocampal region, the NAA concentration correlated inversely with semiquantitative assessments of neuronal loss and neurofibrillary tangles. The gamma-aminobutyric acid levels in both hippocampus and cerebellum of an age- and a postmortem interval-matched subset of AD brains were lower than those of the controls. Because the cerebellum is generally thought to be unaffected by AD, the NAA decrease in the Alzheimer cerebellum may be due to lesions of either the Alzheimer or non-Alzheimer type in contralateral cerebrum.

Rectal carcinoid metastatic to the skeleton. Scintigraphic and radiographic correlation.

Compared to other primary neoplasms, bone metastases from carcinoid tumor are rare. Because some lesions may be clinically or radiographically occult, the radionuclide bone scan can be very helpful in delineating the extent of disease. The authors report a case of a patient with clinically occult widespread metastatic disease detected by bone scan, with radiographic correlation.

SLE myocarditis. Detection by Ga-67 citrate scintigraphy.

Cardiac uptake of Ga-67 in myocarditis has been described in association with a number of disease entities. However, there are no reports in the current literature describing Ga-67 uptake in myocarditis due to systemic lupus erythematosus, a disease that often involves the heart. The authors present the case of a patient with a long history of systemic lupus erythematosus in whom new ECG changes and left ventricular wall motion abnormality developed, and who demonstrated significant global myocardial uptake on Ga-67 scintigraphy. Other etiologies including myocardial infarction, epicardial coronary disease, pericarditis, endocarditis, dilated cardiomyopathy, and viral infection were excluded during extensive work-up.

MAI osteomyelitis. 18-year scintigraphic follow-up.

Mycobacterium avium-intracellulare osteomyelitis is an infrequently reported entity, especially in immunocompetent patients. When multifocal, the imaging findings can be confusing, simulating metastatic disease or other bone lesions. An immunocompetent patient with multifocal Mycobacterium avium-intracellulare osteomyelitis is presented who has been followed for 18 years and experienced episodes of exacerbations and further dissemination of her disease, followed by periods of partial remission and clinical quiescence. Bone scintigraphy was very useful in evaluating the extent of involvement and monitoring response to treatment.

Gastric duplication cyst. Scintigraphy and correlative imaging.

Gastric duplication cysts are uncommon congenital anomalies, and examples imaged with scintigraphy are rarely reported in the literature. The authors report an infant with duplication of the stomach, which was extensively evaluated using scintigraphy, ultrasound, computed tomography, and upper gastrointestinal series. The role of multimodality imaging is discussed, and correlative surgical and histologic findings are presented.

Crossed renal ectopia. Correlative imaging.

Anatomic variants of the kidneys are often noted during renal scintigraphy and other imaging studies. These conditions have a variable effect on overall renal function and can cause confusion, both clinically and on initial imaging. The authors describe a case of unfused, crossed renal ectopia in an elderly woman that appeared to be an abdominal mass and was subsequently evaluated by computed tomography, ultrasound, and scintigraphy.

Computed tomography of the aortopulmonary window: normal anatomy and pathology.

There can be many diagnostic pitfalls in the evaluation of the aortopulmonary window by chest radiography alone. Large masses that are easily identified on computed tomography may be essentially undetectable; also the appearances of aortopulmonary window lesions on conventional radiographs are frequently nonspecific, or may even be misleading. Careful evaluation of this region of the mediastinum is important because the aortopulmonary window is commonly the site of adenopathy secondary to neoplastic and inflammatory diseases, as well as vascular pathology. After review of the normal anatomy of the aortopulmonary window, seven selected cases are presented that demonstrate the importance of computed tomography in arriving at the correct diagnosis when conventional chest radiographs are nonspecific or equivocal.

CT evaluation of distended pericardial recess presenting as a mediastinal mass.

A patient with a remarkably distended pericardial recess due to massive pericardial effusion mimicking a mediastinal mass is reported. The nature of the "mass lesion" was clearly demonstrated by CT and the lesion disappeared after removal of the pericardial effusions. The importance and usefulness of CT in evaluation of pericardial recesses is stressed.

Aortopulmonary window lesions: detection with chest radiography.

A retrospective morphologic study of 80 cases was undertaken to determine factors affecting detectability of computed tomographically (CT) proved aortopulmonary (AP) window lesions on conventional posteroanterior (PA) and lateral chest radiographs. Criteria used for determining abnormality were: solitary lymph node enlargement over 1.5 cm or three or more 1-cm nodes and obvious large masses or vascular anomalies. CT scans and corresponding PA and lateral radiographs were analyzed for lesion detectability, size, and location. In 49% of cases there was no detectable lesion in the AP window on radiographs; a definite AP window lesion was seen in 41%, and 10% were equivocal. Major contributing factors to low detectability of AP window lesions on radiographs include size and, more important, location of the lesion. An additional 45 cases of CT-proved normal AP windows were retrospectively reviewed to determine the false-positive rate of PA and lateral radiographs in detection of AP window lesions: 43 (96%) were classified as negative, the remaining two (4%) as equivocal. Although the AP window is a small space, it is the site of many pathologic conditions; the study results indicate that CT may be an essential procedure for its evaluation.

Pneumococcal sacroiliitis.

We report an unusual case of Streptococcus pneumoniae sacroiliitis in a previously healthy 31-year-old woman. Six cases of pneumococcal sacroiliitis have been reported; the only two cases in adults occurred in young women in the preantibiotic era. Our patient had fever and a depressed level of consciousness, with subsequent right buttock and thigh pain. Blood cultures revealed S pneumoniae, and a bone scan showed increased tracer activity in the right sacroiliac joint. Although the cerebrospinal fluid white blood cell count was only 3/microL, culture of cerebrospinal fluid grew S pneumoniae. Our patient was successfully treated with a 6-week course of intravenous antibiotics (penicillin G after an initial week of ceftriaxone), followed by 2 weeks of oral penicillin therapy.

Impact of clinically significant heterotopic ossification on functional outcome after traumatic brain injury.

OBJECTIVE: To assess heterotopic ossification's (HO) impact on functional outcome after TBI. DESIGN: Retrospective with matched control group, single center. SETTING: TBI Model System of Care at the Medical College of Virginia of Virginia Commonwealth University, Richmond, VA. PARTICIPANTS: Twenty-six patients with TBI and triple-phase bone scan confirmed HO were matched with 26 patients without clinical evidence of HO. MAIN OUTCOME MEASURES: Acute and rehabilitation lengths of stay (LOS), Admission and Discharge Functional Independence Measure (FIM) scores, FIM change, FIM efficiency (FIM gains per week), and discharge disposition. RESULTS: The two groups had similar acute care LOS. Patients with HO had significantly longer inpatient rehabilitation LOS and significantly lower FIM mobility and activities of daily living subscale scores on admission and discharge. FIM efficiency was significantly lower for the group with HO. Significantly fewer patients with HO were able to be discharged to home. CONCLUSIONS: HO is associated with a poorer functional outcome; however, it is not clear whether HO causes the decreased function or whether it may serve more generally as an indicator of those patients who will not progress as far or as rapidly during inpatient rehabilitation.

Analysis of brain and cerebrospinal fluid volumes with MR imaging: impact on PET data correction for atrophy. Part II. Aging and Alzheimer dementia.

A new, computerized segmentation technique, in which magnetic resonance (MR) imaging produces accurate volumetric measurements of brain and cerebrospinal fluid (CSF) without the limitations of computed tomography, was used in a retrospective analysis of digitized T2-weighted MR images of 16 healthy elderly control subjects and 16 patients with Alzheimer dementia. Ventricular and extraventricular CSF was quantified, and the effects of aging were studied; in both groups, the atrophy measurement was used to correct metabolic values obtained with positron emission tomography. Patients with Alzheimer dementia had higher total CSF; extraventricular, total ventricular, and third ventricular CSF volumes (49%, 37%, 99%, and 74%, respectively); and 7% lower brain volumes than the control group. The patients also showed a more marked decline in brain volumes and a greater increase in CSF volumes with advancing age than the control group. They had a 25.0% increase in corrected whole-brain metabolic rates; the control group had only a 15.8% increase. The use of this technique may provide a basis for further studies of aging and dementia, including regional volume analysis.

An in vitro 1H nuclear magnetic resonance study of the temporoparietal cortex of Alzheimer brains.

The concentrations of selected metabolites in the posterior temporoparietal cortex of 13 Alzheimer's diseased (AD) and four nondemented postmortem brains (of individuals between the ages of 63 and 95) were determined using high-resolution 1H nuclear magnetic resonance (NMR) spectroscopy. The estimates for glutamate and inositol for AD brains did not show any statistically significant difference (P > 0.05) from those for the nondemented brains. The putative neuronal marker N-acetyl aspartate (NAA), creatine, and GABA were decreased in AD brains compared with the nondemented brains. The estimates for creatine, glutamate, and GABA showed significant linear correlations with those of NAA. Creatine, glutamate, GABA, and NAA appeared to be negatively correlated with the neurofibrillary tangles. Our results support a neuronal loss in the posterior temporoparietal cortices of AD brains.