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Positron emission tomography (PET) is an emerging clinical imaging technique that is facing the challenges of expansion in a period of imminent health care contraction and reform. Although PET began showing utility in clinical medicine in the mid-1980s [1], its proliferation into mainstream medical practice has not matched that of other new imaging technologies such as MR imaging. Many factors have contributed to this, including the changing health care economy, the high cost of PET, the length of time it takes to develop a PET facility, and its inherent complexity. In part because of the proliferation of the use of other technologies and the general explosion of costs, insurance carriers are now holding diagnostic techniques, including PET, to stricter standards of efficacy. New techniques must show improvement in long-term outcome of patients, a difficult task for diagnostic tools. In addition to these issues, PET is an expensive technology that requires highly trained multidisciplinary personnel. Questions have also been raised about the most appropriate mechanism for regulation of PET isotope preparation, leading to speculation about future regulatory requirements. The current pioneers of PET must meet these challenges in order for it to become a routine imaging technique. Because of its clinical value, PET will probably survive despite the challenges. For many reasons, though, not every hospital should necessarily develop PET services. Conversely, many hospitals without this technology should consider acquiring PET. The purpose of this article is to identify the financial, operational, and clinical challenges facing PET centers today, describe potential organizational configurations that may enable PET to survive in an antitechnology environment, and delineate which institutions should consider this new technology.

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The value of color Doppler sonography in evaluating newly diagnosed Budd-Chiari syndrome in five patients was studied. Hepatic venous findings included absence of vessels (one patient), flow reversal (two patients), narrowing (four patients), and tortuosity (three patients). Detected collaterals included hepatic venous to hepatic venous (four patients), hepatic venous to subcapsular systemic venous (two patients), and portosystemic (three patients). Hepatic venous spectral Doppler waveforms were flat and essentially aphasic in four patients, indicative of distal hepatic venous compression. The inferior vena cava was markedly compressed in two patients and slightly compressed in one. Color Doppler sonography allowed more reliable and confident identification of irregular, compressed, or otherwise abnormal hepatic veins than did conventional sonography. Color Doppler sonography also showed collateral vessels that were undetected with conventional sonography or other imaging techniques. Our results suggest that color Doppler sonography may be a valuable tool in the initial diagnosis and evaluation of suspected Budd-Chiari syndrome.

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Nine patients who had undergone end-to-side portocaval shunts were assessed using a sector real-time color Doppler sonography system. Shunt patency was demonstrated in 8 of 9 patients by detection of color-coded flow within the portal vein, in the anastomotic region, and in the inferior vena cava adjacent to the shunt. Color flow could not be detected in 1 patient. This patient had no evidence of shunt compromise. Spectral Doppler studies were also performed in these patients and flow was demonstrated in all 8. In these instances, information available with color Doppler imaging allowed visualization of the shunt even when it had not been apparent on preliminary real-time grey-scale imaging. This study, which does not assess accuracy, nevertheless suggests that color flow Doppler sonography may prove useful in assessing patients with portocaval shunts.

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Clinical diagnosis of patients with acute scrotal pain is frequently imperfect. Imaging, using nuclear medicine scintigraphy and hand-held continuous-wave Doppler ultrasound devices, has been used in these patients. We retrospectively analyzed 28 consecutive patients referred for scrotal sonography, all of whom had been imaged using color Doppler sonography. Of 22 patients with confirmed diagnoses, 11 had acute epididymitis/orchitis and 11 had another diagnosis. Ten of 11 patients with acute epididymitis/orchitis had increased epididymal flow. Eight also had increased testicular flow. None of the 11 patients without acute epididymitis/orchitis had increased flow. Our data suggest that color Doppler sonography may be useful in establishing the diagnosis of acute epididymitis/orchitis. This might decrease the need for scrotal exploration. No distinction could be made among scrotal lesions in the nonacute epididymitis/orchitis group. Sensitivity was inadequate to reliably detect flow in normal testicles, a prerequisite to accurately diagnose torsion. Newly improved sensitivity may enhance the utility of color Doppler sonography in assessing patients with acute scrotal pathology.

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High-resolution real-time sonography not only provides a noninvasive means of diagnosing hip effusions, but also provides easy access for arthrocentesis. Nineteen sonographically guided hip arthrocentesis were performed in 18 patients. In 13 of 19 patients aspirated, capsular distension was present. In 10 of 19 patients, fluid could be aspirated from the joint space (volume varying from 1 to 9 mL). Saline lavage was performed in 12 of the 19 joints needled. Intra-articular location was confirmed by observation during distension on real-time images or by successful aspiration. Sonographically guided arthrocentesis has potential advantages over conventional fluoroscopic techniques. These include a lack of ionizing radiation, superior visualization of needle location within the joint capsule, and the ability to diagnose soft tissue and periarticular abnormalities generally not seen fluoroscopically.

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A prospective analysis of the hepatoduodenal ligament (HDL) in 205 patients with abdominal pulsed Doppler sonography supports the conclusion that Doppler ultrasound is a useful adjunct to routine scanning in this area. Abdominal pulsed Doppler sonography allows reliable differentiation among the HDL structures by identifying and characterizing flow in the portal vein and hepatic arterial structures, while demonstrating no flow in the bile ducts. Proper hepatic arterial signal was obtained in 190 (92.7%) patients. Portal venous signal was obtained in virtually all (203 of 205-99%) patients. Abdominal Doppler sonography shows promise in its ability to provide definitive diagnostic information in situations where images alone may prove misleading. Doppler sonography can differentiate similarly sized bile ducts and arteries and detect dilated arterial and venous structures simulating dilated bile ducts.

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A new type of ultrasound signal processing ("FM sonography") appears to be beneficial compared to conventional ultrasound ("AM sonography") in some applications (e.g., diffuse liver disease and prostatic carcinoma). Despite these possible advantages, it is doubtful FM sonography will be widely used unless it is at least as useful as conventional (AM) sonography in all common applications. Fifty-five patients with suspected gallbladder disease were independently evaluated with both AM and FM sonography. The two modalities were blindly and prospectively compared for accuracy in detecting gallstones and for image quality. No statistically significant difference was found between images produced by FM and conventional signal processing. FM had an accuracy of detecting gallstones of 98.1%, compared to 96.2% for AM. Overall, FM accuracy was 97.7%, while AM had an overall accuracy of 97.3%. Other useful sonographic signs were evaluated (gallbladder wall thickness, diameter of common duct). No AM/FM difference was noted. Our data suggest that FM-only imaging could be performed in patients with suspected gallbladder disease without loss of accuracy.

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Epithelioid hemangioendothelioma (EHE) is a rare, malignant neoplasm of vascular origin arising in soft tissues, lung, and liver. Four cases of hepatic EHE are reported, and 49 previously reported cases are reviewed. The tumor occurs in adults of all ages; 66% of patients are women. The prognosis is variable. Computed tomographic findings suggest the tumor begins as multiple hepatic nodules that grow and coalesce, forming large confluent masses preferentially involving the liver periphery. Extensive hepatic involvement is associated with enlargement of uninvolved portions of the liver and splenomegaly. Awareness of the radiologic features is helpful because clinical findings are nonspecific, and biopsy specimens may be misinterpreted as carcinoma or venoocclusive disease.

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CT findings in 23 patients with amebic liver abscess were analyzed retrospectively. A solitary abscess was present in 17 patients. Five patients had two to five lesions. One patient, a male homosexual, had 15 abscesses. Of the 46 abscesses, 74% occurred in the right lobe. The lesions were generally round or oval. One-half of the abscesses were 2-6 cm in diameter; 11% measured 13-16 cm. An enhancing wall was present in most cases. An incomplete rim of edema was seen in eight abscesses. The margin of the abscess was smooth in 63% and nodular in 37%. Internal septations were noted in 30%. Four patients had focal intrahepatic biliary dilatation peripheral to an abscess. One patient had intraabscess hemorrhage. Extrahepatic abnormalities were present in 18 patients; right pleural effusion (nine), perihepatic fluid collection (five), gastric or colonic involvement (eight), and retroperitoneal extension (one). Gas within an abscess was due to hepatobronchial fistula in one patient and hepatocolic fistula in another. Amebic abscess should be included in the differential diagnosis when CT shows one or more cystic or complex masses in the liver, especially when there is evidence of extrahepatic extension.

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Magnetic resonance imaging (MRI) was performed in 22 patients at various times (0-3) years) following radiation therapy to the spine. T1 and T2 weighted images were obtained at 0.5 Tesla. Increased signal was seen after 800-6000 rads (8-60 Gy). Marrow effects corresponded to radiation ports. Recurrent tumor was clearly separated from fatty replacement. This was much better seen on T1 weighted images. Five patients that had MRI during their course of radiotherapy (XRT) did not have increased signal on T1 images of the bone marrow. The earliest fatty marrow change was seen nine days following completion of 3000 rads (30 Gy) XRT over one month's duration. One patient who received 800 rads (8 Gy) to the upper thoracic spine for eosinophilic granuloma had no radiation effects on MRI when imaged 16 days following completion of XRT given over five days. Fatty marrow change was seen in this patient on MRI six months later. MRI was particularly useful in defining the extent of prior radiation effects when repeat therapy was needed.

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Graves disease is a common diffuse abnormality of the thyroid gland usually characterized by thyrotoxicosis. We performed color-flow Doppler sonography in 16 patients with Graves disease and compared the results with those in 15 normal volunteers and 14 patients with other thyroid diseases (eight with multinodular goiter, four with focal masses, and two with papillary thyroid carcinoma). All 16 Graves disease patients exhibited a pulsatile pattern we call "thyroid inferno." This pattern consists of multiple small areas of intrathyroidal flow seen diffusely throughout the gland in both systole and diastole. In systole, both high-velocity flow (color coded white) and lower velocity flow (color coded red and blue) were noted. In diastole, fewer areas of flow and lower velocity flow were noted. Patients with Graves disease also exhibited color flow around the periphery of the gland. The inferno pattern did not occur in normal subjects or in patients with other thyroid diseases. On occasion, focal areas of intrathyroidal flow were detected in patients with multinodular goiter and focal thyroid masses. High-resolution gray-scale images did not show the small vascular channels from which the flow signal originated. Color-flow Doppler sonography shows promise as a cost-effective, noninvasive technique for diagnosing Graves disease.

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Focal gallbladder tenderness is the most important physical finding in suspected acute cholecystitis. We describe a technique using palpation of the abdomen with the placement of a radioactive marker on the point of maximum tenderness. Correlation of the marked area to the location of the gallbladder fossa is made. This integration of palpation and scintigraphy might enhance the cholescintigraphic diagnosis of acute cholecystitis.

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Nasogastric administration of activated charcoal is effective in decreasing the half-life of amitriptyline. A case is reported in which this therapy for amitriptyline overdose led to charcoal bezoar formation and small-bowel obstruction. Amitriptyline's atropinic side effects on the gut make this a possible complication in such patients.

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Hepatic magnetic resonance (MR) imaging was performed in 12 patients with 13 amebic liver abscesses. While no specific image or intensity pattern was noted, most lesions were round or oval with smooth, well-defined margins; had decreased signal intensity compared with that of liver parenchyma on T1-weighted images and increased signal intensity on T2-weighted images; and had prominent, often multiple rims of variable signal intensity. Signal homogeneity within the abscess was present more often on T1- than on T2-weighted images. Diaphragmatic disruption was seen in two cases on coronal MR images. An amebic empyema was differentiable from sympathetic pleural effusions by its hyperintensity on both T1- and T2-weighted images. In patients who also underwent computed tomography (CT) or ultrasonography (US), no lesion was missed with any modality, and except for shape, no consistent features were found among images obtained with the different modalities. The data suggest that CT, US, and MR imaging are comparably effective in the detection of amebic abscess.

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Scintiangiography and hepatobiliary scintigraphy were performed in 45 patients with abdominal trauma. There were 18 gunshot wounds, six stab wounds, and 21 blunt injuries. Thirty-one of 45 patients showed abnormalities (69%). There were nine bilomas (4 with leaks), three leaks without biloma, (7 total leaks), five liver hematomas, three liver infarcts, one liver abscess, four renal injuries, one post-traumatic hepatic artery aneurysm, one acute acalculus cholecystitis, and four bowel injuries including one fistula, two obstructions, and one stricture. Two of the renal injuries and the hepatic artery aneurysm were identified only during scintiangiography. Eighteen of 38 gallbladders were not visualized despite normal bowel transit and delayed views to 4 hours (47%). Fourteen of 16 gallbladders were grossly normal at surgery, one had gallstones, and one had post-traumatic acalculus cholecystitis (6%). Hepatobiliary scintiangiography showed unique characteristics of vascular and renal lesions that were not seen on routine images. Sulfur colloid had no advantage over disofenin in evaluating liver injuries in nine cases. A high percentage of nonvisualized gallbladders (47%) were noted in acutely traumatized patients, and caution is recommended in diagnosing acute cholecystitis in the face of trauma.

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The Kock continent ileal urinary reservoir (Kock pouch) is a new form of urinary diversion that, due to its advantages over previous techniques of urinary bypass, will probably become widespread in urologic practice. When bone imaging is performed in the presence of the Kock pouch, the unusual configuration of the pouch may obscure or simulate osseous lesions. An understanding of the surgical anatomy as well as the planar and SPECT scintigraphic appearances of the Kock pouch is necessary to avoid errors during interpretation. This series of 51 bone images reports on the variable scintigraphic appearance of the Kock pouch. In addition, the incidence and type of potentially avoidable pitfalls in the interpretation of bone imaging when this form of urinary diversion is used are evaluated.

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