Quantitative assessment of truncal FDG-PET examination with postinjection transmission scan —comparison with preinjection transmission scan—

The purpose of this study was to assess the quantitative accuracy of truncal FDG PET with a postinjection transmission scan. METHODS: Ten subjects with lung cancer were recruited for this study. Prior to the emission scan, a transmission scan was performed for 10 min. All subjects received 370 MBq of intravenous administration of FDG prior to a 60-min emission scan. Immediately following the emission scan, a postinjection transmission scan was performed. Emission data from 40 to 60 min postinjection were reconstructed with either pre- or postinjection transmission data and converted to a standardized uptake value (SUV) image. On each SUV image, 5 regions of interest were placed and regions of interest on the SUV image with a postinjection transmission scan (SUVpost) were plotted against those with preinjection transmission (SUVpre), and a regression line was generated. Using the slope and Y-intercept of the regression line, percent error of estimation of the SUV was calculated based on the following equation: % error = ISUVpre - SUVpostI x 100/SUVpre. RESULTS: In the low SUV area (SUV = 1), the averaged percent error was 9.4 +/- 12.0% (mean +/- SD), whereas in the high SUV area (SUV = 10), the averaged percent error was 2.8 +/- 3.1%. The least percent error was 1.8 +/- 1.8% (SUV = 3.8) in this study. CONCLUSION: In the study on truncal FDG PET with postinjection transmisson scan, the quantitative accuracy was preserved and the method is clinically available.     

小儿胃食管反流milk scan临床应用进展

胃食管反流（GER）是常见的消化系统疾病,其发病率高,长期、严重的GER危害严重,GER的早期检出对其治疗至关重要。milk scan是一种主要用于小儿GER、胃排空、肺吸入等疾病及GER发病机制的相关研究的检查方法,其临床应用范围广泛,但灵敏度、特异度不高,在我国关于milk scan的研究报道不多,该文主要对milk scan在小儿GER中的技术研究、临床应用进展等进行综述。     

Quality of planar whole-body bone scan interpretations—a nationwide survey

PURPOSE: The purpose of this study was to investigate, in a nationwide study, the inter-observer variation and performance in interpretations of bone scans regarding the presence or absence of bone metastases. METHODS: Bone scan images from 59 patients with breast or prostate cancer, who had undergone scintigraphy due to suspected bone metastatic disease, were studied. The patients were selected to reflect the spectrum of pathology found in everyday clinical work. Whole body images, anterior and posterior views, were sent to all 30 hospitals in Sweden that perform bone scans. Thirty-seven observers from 18 hospitals agreed to participate in the study. They were asked to classify each of the patient studies regarding the presence of bone metastasis, using a four-point scale. Each observer's classifications were pairwise compared with the classifications made by all the other observers, resulting in 666 pairs of comparisons. The interpretations of the 37 observers were also compared with the final clinical assessment, which was based on follow-up scans and other clinical data. RESULTS: On average, two observers agreed on 64% of the bone scan classifications. Kappa values ranged between 0.16 and 0.82, with a mean of 0.48. Sensitivity and specificity for the observers compared with the final clinical assessment were 77% and 96%, respectively, for detecting bone metastases in planar whole-body bone scanning. CONCLUSION: Moderate inter-observer agreement was found when observers were compared pairwise. False-negative errors seem to be the major problem in the interpretations of bone scan images, whilst the specificities for the observers were high.     

The role of bone scan in the diagnosis of Jaffé-Lichtenstein-Uehlinger syndrome

The case of a 12-year-old girl with Jaffé-Lichtenstein-Uehlinger syndrome is presented. A bone scan pattern exhibits clinical symptoms, X ray images and histological findings are described in a case of polyostotic form of the fibrous dysplasia. A biopsy with histology was performed in consideration of bone scan findings and a confirmed final diagnosis.     

‘Cold spot’ on bone scan at the site of primary osteosarcoma

A 5-year-old girl presented with a rapidly growing osteosarcoma of the proximal right tibia. The radiographically osteoblastic lesions appeared as a cold on the ^99mTc-MDP bone scan. Possible explantations for this unusual finding on the bone scan are discuessed.     

How useful is contrast enhancement after a normal unenhanced computed tomography brain scan?

An audit was performed of contrast use in 400 CT brain scans performed with and without contrast enhancement; all 400 scans were re-read by a second reader who did not know the result of the original reading. From this initial series 184 scans were identified in which the unenhanced series had been read as normal by both observers. Of these 184 studies, only one enhanced scan showed an abnormality, and this lesion is thought to be benign. In conjunction with published literature it is concluded that it is reasonable not to give contrast if there is a low expectation of a lesion being present, and if the unenhanced scan is normal. Protocols are presented for the use of intravenous contrast in CT brain scans.     

Can the three-phase bone scan differentiate osteomyelitis from metabolic or metastatic bone disease?

The three-phase bone scan has been reported of value in the diagnosis of osteomyelitis. The use of a radionuclide angiogram, an immediate postinjection "blood pool" image, and 2 to 3 hour delayed image have been useful in separating nonosseous inflammatory disease from osteomyelitis. However, dependence on increased blood flow and focal hyperemia for this diagnosis may limit the use of the study if other processes are shown to produce similar results. To identify limitations of the three-phase bone scan we studied 14 patients with metastatic bone disease and nine patients with Paget's disease. Blood flow results showed no increase in three of 14 patients with metastases, intermediate increase in seven of 14 patients with metastases and two of nine patients with Paget's, and intense increase in four of 14 patients with metastases and seven of nine patients with Paget's. All patients showed increased focal activity in the immediate "blood pool" and delayed images. We conclude that because of increased flow Paget's disease may be difficult to separate from osteomyelitis. However, metastatic disease can often be differentiated on the basis of quantitative focal hyperemia. The three-phase bone scan remains of value in the diagnosis of osteomyelitis, but other diseases of bone must be included in the differential diagnosis.     

What happens after a lung scan? Management and outcome of patients in a regional hospital

Pulmonary embolism (PE) remains a common preventable cause of death in hospitalized patients. The purpose of this study is to examine the in-hospital management, complications of treatment and clinical outcomes of inpatients undergoing lung scintigraphy for the diagnosis of PE in a regional hospital. Two hundred consecutive inpatients with suspected PE were enrolled. The results of lung scans, stratified according to the probability of pulmonary embolism, were correlated with anticoagulation status, discharge diagnosis, haemorrhagic complications and clinical outcome at 6 months. The use of complementary imaging investigations was also determined. Other imaging was performed infrequently (Doppler ultrasound in 18% of patients, CT pulmonary angiography (CT-PA) in 0.5% and conventional pulmonary angiography in 4% of patients). Long-term anticoagulation was initiated in 66 patients (33%), including 10 with intermediate probability lung scans (IPLS) who had no further investigations. Major haemorrhage occurred in 14% of all long-term anticoagulated patients followed up. The recognized recurrence rate was very low (3%) and there was no documented mortality from PE. Most patients with suspected PE are treated on the basis of the lung scan result without further tests. However, other imaging (especially CT-PA and conventional pulmonary angiography) should be performed prior to anticoagulation in patients with IPLS in whom the diagnosis is in doubt. Standard anticoagulation for 6 months appears to be effective for PE, and the recurrence rate is low. However, it has a significant risk of major haemorrhagic complications.     

Ga-67 tumor scan in malignant diffuse mesothelioma —Comparison with CT and pathological findings—

Malignant diffuse mesothelioma is characterized by more difficult diagnosis and worse prognosis than other pleural tumors. In the Department of Thoracic Surgery, Hyogo Medical Center for Adults, 11 patients underwent panpleuropneumonectomy for this disease between January, 1988 and March, 1993. In 7 of these cases, Ga-67 scans were obtained before the operation. To clarify the factors affecting Ga-67 uptake in the pleural tumor, we compared Ga-67 uptake on the involved side of the thorax with CT and the pathological findings of the tumor. Regarding the use of Ga-67 scan imaging for the diagnosis of this disease, a number of related findings must be considered, such as an encircled wide Ga-67 uptake in the thickened pleural involvement and a diffuse slight Ga-67 uptake on the affected side with very slight involvement of the pleura. When the involved pleural thickness was over 6 mm, a definite correlation was found between the degree of Ga-67 uptake and the macroscopic thickness of mesothelioma in resected specimens. Thickness of the pleura on CT images demonstrates the real tumor thickness in the case of thickened involvement but in the case of thin involvement the real thickness of active mesothelioma could not be identified. No definite correlation was found between the degree of Ga-67 uptake and the histological type, or among microscopic findings, such as the extent of tumor parenchyma, interstitial volume and tumor vascularity. Our results suggest that the Ga-67 scan is very useful for revealing the extent of pleural involvement, especially when this involvement is more than 6 mm thick.     

Calf injuries in professional football: Treat the patient or the scan? – A case study

ObjectiveTo describe a case of a professional football player with significant imaging findings despite a rather innocuous clinical presentation with gradual onset of calf pain and who was able to continue training and playing with minor medical intervention. To discuss some of the limitations of existing muscle injury grading systems and their potential to cover the full range of injury presentations for calf injuries.DesignCase report.SettingA professional football player was assessed by physical examination, clinical testing and imaging (MRI) after a gradual onset of a calf injury. After returning to training and competition, a follow-up of his symptoms was performed with regular ultrasound imaging assessments.ParticipantA professional football player (35 years, 1.90 m, 88 kg) male, African, striker, playing in the Professional Arabian Gulf League.ConclusionThe discordance between the clinical presentation and the imaging findings resulted in a challenging situation regarding the decision of whether to allow the player to train and compete. In addition, existing muscle injury grading systems do not seem to cover the full range of injuries seen in clinical practice.     

Comparison of gallium-67 citrate and technetium-99m tetrofosmin scan to detect Hodgkin’s disease

OBJECTIVE: The purpose of this study was to compare the usefulness of gallium-67 citrate (67Ga) and technetium-99m tetrofosmin (Tc-TF) scan to detect Hodgkin's disease (HD). METHODS: In this study, 24 patients with HD underwent 67Ga and Tc-TF scan before receiving any therapy. RESULTS: 67Ga scan could detect HD in all 24 (100%) patients. Tc-TF scan could detect HD in 22/24 (91.6%) patients, but it was false-negative in one case of infradiaphragmatic HD and in another case with chemotherapy resistance. There was no significant difference in detection sensitivity between 67Ga and Tc-TF scan. CONCLUSIONS: We conclude that Tc-TF scan can not replace conventional 67Ga scan to detect HD.     

Coincidental visualization of an atypical bronchial carcinoid on Tc-99m-sestamibi scan in Kallmann’s syndrome

We report a case of an atypical bronchial carcinoid showing sestamibi uptake. A 27-year-old man with Kallmann's syndrome and hyperparathyroidism had parathyroid scintigraphy with 99mTc-sestamibi. A focal uptake was observed on the right perihilar region, and this right perihilar mass was demonstrated on computed tomography and proved histologically to be an atypical bronchial carcinoid tumor. Factors which may explain the tumoral avidity for sestamibi are increased blood flow, transmembrane potentials of plasma and mitochondrial membranes and the relative number of mitochondria present in the cells of this carcinoid tumor. The importance of this case is the coincidence of an atypical carcinoid in a patient with significant failure of secondary sexual characteristics, right renal agenesis and bilateral anosmia associated with Kallmann's syndrome.     

Ventilation/perfusion scan and dead space in pulmonary embolism: are they useful for the diagnosis?

The diagnostic strategy for pulmonary embolism, based on the mismatch of the ventilation/perfusion scan, was developed some 30 years ago on the following assumption: since the disorder involves the pulmonary vessels, it was surmised that in the embolized regions lung alveoli are unperfused or poorly perfused but well ventilated. Hence, it was inferred that this disorder was characterized, unlike parenchymal disease, by ventilation/perfusion mismatch in the affected lung zones and by an obvious increase of wasted ventilation, i.e., dead space. As matter of fact, experimental evidence on the redistribution of ventilation away from the vascular occluded lung had been already obtained in the early 60s of the last century. More recently, the behavior of regional pulmonary ventilation (V(A)) and blood flow (Q) in patients with acute pulmonary embolism (APE) has been studied by applying the multiple inert gas elimination technique (MIGET). It has been shown that the development of lung units with high V(A)/Q ratio (those with relative prevalence of perfusion obstruction) is accompanied by substantial redistribution of ventilation away from these units. Furthermore, radioisotopic techniques, used to visualize the topographic distributions of V(A) and Q in the same patients studied by MIGET, have shown reduced or absent V(A) in the embolized regions. This may occur by different mechanisms in the various stages of APE: bronchoconstriction mediated by local hypocapnia, atelectasis (occasionally hemorrhagic) related to alteration of surfactant production, bronchiolar obstruction and pulmonary infarction ascribed to degenerative and/or necrotic changes secondary to insufficient blood flow. In dogs and humans alike, the dead space measured by MIGET does not increase and that obtained from CO2 increases far less than the amount of unperfused lung in APE thus confirming a substantial redistribution of ventilation away from the embolized lung zones. Taken together, all these observations provide the pathophysiological explanation of the unacceptedly low level of sensitivity for the diagnostic strategy of APE based on the mismatch of the ventilation/perfusion scan.     

Can homogeneous preparation encoding (HoPE) help reduce scan time in abdominal MRI? A clinical evaluation

PURPOSE: To evaluate time efficiency, image quality, and diagnostic value of a clinical routine homogeneous preparation encoding (HoPE) imaging protocol in different malign and inflammatory abdominal conditions. MATERIALS AND METHODS: A total of 14 healthy volunteers and 40 patients were examined after written informed consent and approval of the local ethics committee. A standard abdominal T1-weighted (T1W) fat-saturated gradient-echo protocol was compared to the HoPE sequence protocol ensuring for comparable imaging parameters. Examinations were performed on a 1.5-T Siemens Avanto equipped with a multichannel body-array coil. Image analysis was performed with respect to contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR), level of fat suppression (FS), generation of artifacts, and overall image quality by two blinded radiologists. RESULTS: In addition to comparable results in overall image quality and FS level, the HoPE sequence protocol provided a reduction in acquisition time of up to 40%. In addition, artifact generation was same or even reduced with respect to pulsation. Quantitative SNR analysis showed strong correlation between HoPE and the conventional method. CONCLUSION: The HoPE technique is a feasible and time-saving alternative for clinical abdominal MRI. Future studies will have to be conducted on larger patient collectives to strengthen the impact of this promising technique for FS imaging and to prove its accuracy.     

Low contrast volume run-off CT angiography with optimized scan time based on double-level test bolus technique – feasibility study

Purpose

To verify the technical feasibility of low contrast volume (40 mL) run-off CT angiography (run-off CTA) with the individual scan time optimization based on double-level test bolus technique.

Materials and methods

A prospective study of 92 consecutive patients who underwent run-off CTA performed with 40 mL of contrast medium (injection rate of 6 mL/s) and optimized scan times on a second generation of dual-source CT. Individual optimized scan times were calculated from aortopopliteal transit times obtained on the basis of double-level test bolus technique – the single injection of 10 mL test bolus and dynamic acquisitions in two levels (abdominal aorta and popliteal arteries). Intraluminal attenuation (HU) was measured in 6 levels (aorta, iliac, femoral and popliteal arteries, middle and distal lower-legs) and subjective quality (3-point score) was assessed. Relations of image quality, test bolus parameters and arterial circulation involvement were analyzed.

Results

High mean attenuation (HU) values (468; 437; 442; 440; 342; 274) and quality score in all monitored levels was achieved. In 91 patients (0.99) the sufficient diagnostic quality (score 1–2) in aorta, iliac and femoral arteries was determined. A total of 6 patients (0.07) were not evaluable in distal lower-legs. Only the weak indirect correlation of image quality and test-bolus parameters was proved in iliac, femoral and popliteal levels (r values: −0.263, −0.298 and −0.254). The statistically significant difference of the test-bolus parameters and image quality was proved in patients with occlusive and aneurysmal disease.

Conclusion

We proved the technical feasibility and sufficient quality of run-off CTA with low volume of contrast medium and optimized scan time according to aortopopliteal transit time calculated from double-level test bolus.