The diagnostic value of hepatobiliary scintigraphy for choledochal cysts in the era of magnetic resonance imaging with cholangiopancreatography and contrast-enhanced hepatobiliary phase: a case report and review.

Objective: Choledochal cysts (CCs) represent cystic dilatations of the intra- or extrahepatic biliary tract. The diagnosis of CCs may not always be straightforward particularly for the intrahepatic subtype. Whereas the gold standard for diagnosing CCs is endoscopic retrograde cholangiopancreatography (ERCP), magnetic resonance cholangiopancreatography (MRCP) is commonly used as primary diagnostic tool for delineation of biliary pathologies including CCs. Methods: We report a case of cystic hepatic lesion near the confluence of bilateral intrahepatic ducts. MRCP shows direct anatomical communication between the lesion and the biliary tract, raising suspicion of a CC. Endoscopic ultrasound shows no communication between the lesion and biliary system. 99mTc-hepatic iminodiacetic acid scintigraphy (hepatobiliary scintigraphy) was subsequently performed, showing no tracer uptake in the concerned cystic hepatic lesion despite visualisation of gallbladder and transit of tracer into the intestine. Overall scintigraphic findings speak against a CC. Conclusion: The case showed conflicting anatomical findings of a CC on MRCP and endoscopic ultrasound. Hepatobiliary scintigraphy and hepatobiliary contrast MRI may both functionally demonstrate communication of a hepatic lesion with the biliary tract. But hepatobiliary scintigraphy offers the advantage of much higher hepatic extraction and hence higher resistance to competition from plasma bilirubin compared with hepatobiliary contrast MRI. The better pharmacokinetics of HIDA confer superior lesion contrast that may offset inferior image spatial resolution, in particular for large lesions and patients with hyperbilirubinaemia. Hepatobiliary scintigraphy should be considered a suitable functional diagnostic modality for CCs even in the era of magnetic resonance imaging with cholangiopancreatography and contrast-enhanced hepatobiliary phase.

Gallium-67 Scan with Single Photon Emission Computed Tomography for the Evaluation and Monitoring of Infected Abdominal Aortic Aneurysms: A 10-Year Case Series.

PURPOSE: This study aimed to evaluate the role of gallium-67 single photon emission computed tomography (SPECT) with contrast computed tomography (CT) in the evaluation and monitoring of infected abdominal aortic aneurysms (IAAA). MATERIALS AND METHODS: A retrospective cohort analysis was performed using prospectively collected data of consecutive patients with IAAA in Princess Margaret Hospital in Hong Kong between January 2010 and December 2020. The patients were identified using the Radiology Information System. RESULTS: All five patients had proven IAAA on CT and/or metabolic imaging. Among them, three were further supported by positive blood culture results. Gallium- 67 SPECT with contrast CT was useful in the detection of residual disease, monitoring, and detection of recurrence. CONCLUSION: Gallium-67 SPECT with contrast CT is helpful for evaluating IAAA. It serves an important role in guiding management, especially during long-term follow-up.

Hybrid Magnetic Resonance Imaging with Single Photon Emission Computed Tomography/Computed Tomography Bone Scan for Diagnosis Of Avascular Necrosis of Femoral Head.

Magnetic resonance imaging (MRI) is a commonly used imaging modality to detect early avascular necrosis (AVN). When MRI is inconclusive, bone scan is helpful in detecting AVN during early phase of the disease. As newer nuclear medicine equipment, such as single photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography, are emerging in medical science, the role of these imaging modalities in AVN of femoral head is re-evaluated.

Ectopic Submandibular Parathyroid Adenoma by Tc-99m Sestamibi SPECT/CT Localization.

We present a 74-year-old woman with primary hyperparathyroidism, with elevated parathyroid hormone and calcium. Tc-99m-methoxyisobutyl isonitrile (sestamibi) planar imaging showed a focus of uptake over the inferior aspect of the right submandibular gland that was localized on the single-photon emission computed tomography with CT.

Salivary Gland Scintigraphy in Patients with Sjogren's Syndrome: A local Experience with Dual-tracer.

OBJECTIVES: To review the findings of the patients with Sjögren's syndrome (SS) having technetium99-m-pertechnetate (99mTc-pertechnetate) and gallium67- citrate (Ga-67) salivary gland scintigraphy in the past eight years. METHODS: The patients with SS, who were referred to our department for salivary gland scintigraphy during January -2008December 2015 were studied using both 99mTc-pertechnetate and Ga-67 citrate scintigraphy. RESULTS: Eighteen patients were included in the study, 17 of whom had positive findings on 99mTc-pertechnetate salivary gland scintigraphy. One patient had negative parotid glands findings on 99mTc-pertechnetate, but positive findings in Ga-67 study. Four patients had asymmetric involvement of the parotid glands, and one patient had asymmetric involvement of the submandibular glands in 99mTc-pertechnetate salivary gland scintigraphy. On the other hand, one patient had only submandibular gland involvement in the 99mTc-pertechnetate scan. Nine patients (18/9) had positive parotid gland findings on Ga-67 study. The involvements of the parotid glands were all symmetrical, except for one patient. No abnormal gallium uptake in the submandibular glands in our patients was noted. CONCLUSION: 99mTc-pertechnetate salivary gland scintigraphy is sufficient for the assessment in the majority of patients with SS. Ga-67 scintigraphy may be a useful supplementary test, especially if the result of 99mTc-pertechnetate scintigraphy is not conclusive.

Improvement of bone mineral density after enzyme replacement therapy in Chinese late-onset Pompe disease patients.

OBJECTIVE: Late-onset Pompe disease (LOPD) is a lysosomal storage disease resulted from deficiency of the enzyme acid α-glucosidase. Patients usually develop a limb-girdle pattern of myopathy and respiratory impairment, and enzyme replacement therapy (ERT) is the only specific treatment available. Recently, LOPD has been associated with low bone mineral density (BMD), but the effect of ERT on BMD is inconclusive. In this report we described our early observations on the change of BMD after ERT in Chinese LOPD patients. RESULTS: We studied four Chinese LOPD patients with different severities of myopathy. All were underweight, and three had osteoporosis at baseline. We found significant weight gain in three patients after ERT and all four patients showed improvement in BMD. The biggest improvement, 84.4% increase in BMD, was seen in a lady with the most prominent weight recovery. Our results suggest that ERT improves BMD in Chinese LOPD and weight gain could be a major contributor to this effect.

Early Enlargement of Aneurysmal Sac and Separation of EndoBags of Nellix Endovascular Aneurysm Sealing System as Signs of Increased Risk of Later Aneurysm Rupture.

Nellix Endovascular Aneurysm Sealing (EVAS) system is a new concept and technology of abdominal aortic aneurysm (AAA) repair. Elective EVAS using Nellix device was performed for a 83-year-old man with AAA. 2-month post-EVAS CTA surveillance demonstrated mild enlargement of aneurysmal sac and separation of the EndoBags, but without detectable endoleak. The patient developed sudden AAA rupture with retroperitoneal hematoma at about 4 months after EVAS. We postulated that early enlargement of aneurysmal sac and separation of EndoBags of Nellix devices after EVAS, even without detectable endoleak, might indicate significant aneurysmal wall weakening with increased risk of later AAA rupture. To the best of the authors' knowledge, this was the first reported case of aortic rupture after EVAS without detectable endoleak during and after the procedure.

Comparing left ventricular ejection fraction measurement using cardiovascular magnetic resonance imaging.

PURPOSE: To compare the accuracy of cardiovascular magnetic resonance (CMR) imaging methods for measuring left ventricular ejection fraction with multiple-gated acquisition (MUGA). CMR imaging methods included in-line tracking, in-line automated tracking with manual adjustment (a semiautomatic technique), and manual drawing techniques. METHODS: Thirty patients were recruited for left ventricular ejection fraction (LVEF) assessment. The LVEF was measured by CMR imaging using in-line automated tracking, the semiautomatic technique, and manual contouring and segmentation. These methods were then followed by a MUGA scan. Results of all 4 methods were compared for LVEF percentage and measuring time. Repeated analysis of variance testing was used to determine any significant difference between the means of measuring the LVEF. A P value of less than .05 was considered statistically significant. RESULTS: The mean LVEF measured by CMR imaging using in-line automated tracking, a semiautomatic technique, and manual drawing were 52.9% (standard deviation [SD] 8.5), 62.3% (SD 8.1), and 62.2% (SD 7.8), respectively. The mean LVEF with the MUGA scan was 64.4% (SD 8.4). The MUGA scan, semiautomatic technique, and manual measurement using CMR imaging were statistically significantly different from the CMR imaging using in-line automated tracking for LVEF calculation (all P values < .01). DISCUSSION: Using in-line automated tracking, the end systolic volume was overestimated, which resulted in the underestimation of the LVEF. A therapeutic plan based on an inaccurate and low LVEF measurement could be dangerous because it might suggest a drug-related cardiotoxicity, and medication might be discontinued. CONCLUSION: A semiautomated technique with manual adjustment of the cardiac contours and basal slice selection in CMR imaging is time saving and comparable with the MUGA scan for the accurate documentation of LVEF.

The role of barium swallow pharyngoesophagography in the management of the globus pharyngeus: our ten years local experience of asian population.

Patients with globus pharyngeus referred for barium swallow pharyngoesophagography in a local hospital from 1/7/1999 to 30/6/2009 were identified. Their fluoroscopic images were reviewed, and their outcomes were used as gold standard. A total of 908 patients with globus pharyngeus were referred for barium swallow in the period. There were 783 patients with normal barium swallow and 125 patients with abnormal barium swallow findings. All patients aged below 30 years had normal barium swallow result and unremarkable follow up. The sensitivity and specificity of barium swallow were 25.6 and 97.5% respectively; and the positive predictive value and negative predictive value were 61.5 and 89.1% respectively. The overall accuracy was 87.6%. Barium swallow is of limited diagnostic value in patients with typical globus pharyngeus, and it is not recommended in these patients, especially with young age.

Imaging patterns of liver uptakes on PET scan: pearls and pitfalls.

OBJECTIVE: PET imaging is becoming increasingly universal, and therefore increased liver uptake is frequently encountered. The purpose of this article is to describe and illustrate the various morphological patterns of increased metabolic activity within the liver with an emphasis on the diagnostic pitfalls and potential limitations. CONCLUSION: Knowing the pitfalls of PET imaging, correlation with clinical background and findings from other imaging modalities are all important in the correct interpretation of increased hepatic activity on PET imaging.

Imaging features of colorectal liver metastasis in FDG PET-CT: a retrospective correlative analysis between CT attenuation and FDG uptake.

OBJECTIVES: Increasing scientific evidence supports the use of fluorodeoxyglucose positron emission tomography/ computed tomography (FDG-PET/CT) in the staging of colorectal carcinoma. A detailed and accurate characterization of tumor biology and imaging characteristics is therefore of paramount importance. The aim of our study was to determine whether CT attenuation, in Hounsfield units, was correlated with FDG uptake in colorectal liver metastasis. METHODS: The clinical and imaging data of patients from our institution with histologically proven colorectal carcinoma who were referred for PET/CT staging were reviewed. For the purpose of our study, we included only those patients who had undergone dual-time-point imaging. A total of 20 patients with 62 hepatic secondaries were identified. The perlesional CT attenuation (in Hounsfield units), FDG uptake (in standardized uptake values SUV 60 and SUV 120), and size (in cm) were determined. Correlation analysis using the Spearman rank correlation coefficient was carried out. RESULTS: A statistically significant positive relationship was observed between perlesional CT attenuation and SUV 60 (r=0.433, P=0.0004). A similar significant positive relationship was shown between perlesional CT attenuation and SUV 120 (r=0.414, P=0.0008). CONCLUSION: Our study suggested that, in colorectal liver metastasis, FDG uptake was positively correlated with CT attenuation. If a lesion appeared to be indeterminate because of apparently low FDG avidity, internal content must be taken into consideration to minimize misdiagnosis and false negatives. We proposed that such a relationship may be due to the mucinous contents of colorectal liver metastasis or degree of tumor necrosis. Further research, particularly on quantification of the extent of mucin production and tumor necrosis, may allow a more precise relationship to be drawn between CT attenuation and FDG uptake.

Predicting bone scan findings using sPSA in patients newly diagnosed of prostate cancer: feasibility in Asian population.

OBJECTIVE: A number of large-scaled studies done in Western countries have proven a positive relationship between serum prostate-specific antigen (PSA) level and prevalence of positive bone scan findings in newly diagnosed prostate cancer (CaP) patients. The objective of this study is to verify that the tendency occurs as well in Asian population, as well as to establish a possible correlation between PSA level, bone scan result, and Gleason score. METHOD: Records of 116 patients diagnosed to have CaP were reviewed retrospectively for bone scan results, PSA levels, and Gleason score. RESULT: Thirty-four patients were proven to have bone metastases based on positive bone scintigraphy result. None of these patients had a PSA level of less than 10 ng/ml. Two patients had PSA level between 11 and 20, and 15 patients had PSA level between 21 and 200. For patients with PSA level over 201, 17 had bone metastases on bone scintigraphy. CONCLUSION: Based on the PSA level, the likelihood of positive bone scintigraphy result can be postulated. According to PSA levels, staging investigations can be more selective for patients with confirmed CaP. The risk of having positive bone scan is so low that it is not required for patients with PSA level less than 10 ng/ml. On the other hand, on studying the correlation between Gleason score and PSA level or bone scan results, no statistically significant relationship was established.

Diagnostic value of SPECT versus SPECT/CT in femoral avascular necrosis: preliminary results.

OBJECTIVE: With the advent of single-photon emission computer tomography/computed tomography (SPECT/CT), its applications and indications have to be evaluated clinically for a more efficient and cost-effective use in patient management. This retrospective study investigated the clinical value of conventional Tc MDP SPECT against SPECT/CT in diagnosing hip avascular necrosis (AVN). METHODS: This retrospective study evaluated all patients who underwent SPECT/CT during the period from 1 March 2008 to 31 July 2009 for possible femoral AVN for which MRI was contraindicated. The SPECT and SPECT/CT images were reviewed separately by two radiologists with different levels of experience in a double-blinded manner. The likelihood of AVN for each symptomatic hip was graded according to the level of confidence. Clinical outcome was considered as the gold standard. The sensitivity, specificity, and accuracy for SPECT and SPECT/CT by each radiologist was obtained and compared with the gold standard. The corresponding receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to evaluate the diagnostic power of SPECT against SPECT/CT. RESULTS: A total of 22 patients and 24 symptomatic hips were analyzed. Seven hips (29%) were confirmed to have AVN. The AUCs obtained from ROC for trainee radiologist for SPECT vs. SPECT/CT were 0.828 and 0.916, respectively. The AUC for specialist radiologist increased from 0.916 to 0.941 with CT. CONCLUSION: We concluded that SPECT/CT is beneficial for the improvement of AUC in ROC on the diagnostic of hip AVN compared with SPECT alone.

Renal length nomogram in Hong Kong Asian children: sonographic measurement and multivariable approach.

AIM: The purpose of our study was to build a multiple renal length nomogram for Hong Kong Asian children based on normal renal ultrasonography. METHODS: All children below the age of 13 years, who underwent ultrasonography in a local Hospital in Hong Kong from 23 September 2008 to 31 January 2009 due to melamine exposure were identified. RESULTS: A total of 3031 normal children were identified. Hong Kong Asian children have smaller kidneys as compared with the Western. Age, bodyweight and body height are the significant factors in the multiple nomogram model of renal length. The interaction between body ln(weight) (ln stands for natural logarithm) and age as well as body height and age are also significant in the model. CONCLUSION: Our study provides a practical multiple nomogram of renal length for Hong Kong Asian children.

Imaging in pediatric urinary tract infection: a 9-year local experience.

OBJECTIVE: Urinary tract infection (UTI) is a common disease entity in children, and a number of imaging options are offered for these patients. The purpose of our study was to retrospectively describe the (99m)Tc-labeled dimer captosuccinic acid (DMSA) renal scintigraphy, ultrasound, and micturating cystourethrography (MCU) findings over a 9-year period. MATERIALS AND METHODS: All children younger than 10 years old who presented to a local hospital in Hong Kong between July 1, 1997, and June 30, 2006, with culture-confirmed UTI and who subsequently underwent DMSA scintigraphy, ultrasound, and MCU were identified. For the purpose of this study, patients with underlying major congenital urinary tract abnormalities were excluded. DMSA scintigraphy was regarded as the gold standard for the diagnosis of renal scarring. DMSA scintigraphy, ultrasound, and MCU findings and clinical outcomes were reviewed and analyzed. RESULTS: A total of 583 children were included in the study. Of these, 432 children (74.1%) had normal findings on ultrasound and on MCU. Only 13 children (3%) of this group had renal scarring as shown on DMSA scintigraphy. The overall negative predictive value (NPV) for excluding renal scarring of combined ultrasound and MCU reached 97%. The NPV was 97.7% in the subgroup of patients 0 to 2 years old. CONCLUSION: For children younger than 2 years with UTI in the absence of underlying major congenital urinary tract abnormalities, we recommend that DMSA scintigraphy may be withheld if findings on both ultrasound and MCU examinations are normal.

High-resolution computed tomography is useful for early diagnosis of severe acute respiratory syndrome-associated coronavirus pneumonia in patients with normal chest radiographs.

OBJECTIVE: We investigated the usefulness of high-resolution computed tomography (HRCT) in early detection of severe acute respiratory syndrome (SARS)-associated coronavirus pneumonia and analyzed HRCT findings associated with potentially more severe disease. METHODS: All patients with suspected SARS and normal chest radiographs on admission within the study period were subjected to HRCT examination. The clinical, radiologic, and laboratory data of patients who were confirmed to have SARS-associated coronavirus infection by a positive nasopharyngeal aspirate, stool or urine reverse transcription-polymerase chain reaction (RT-PCR) and/or serological testing were prospectively followed up and analyzed. Characteristics of patients admitted to the intensive care unit (ICU) and those that were not were compared. RESULTS: Among 47 suspected SARS patients with normal chest radiographs, 27 had SARS-associated coronavirus infection confirmed by RT-PCR and/or positive serological testing. Twenty-five of the 27 (93%) patients had HRCT changes compatible with atypical pneumonia, and all 25 patients developed SARS with progressive clinical deterioration. Ten (40%) had unifocal diseases, and 15 had multifocal diseases (60%). Ten (40%) patients had the diseases confined to 1 single lung in the first HRCT, and both lungs were involved at initial presentation in 15 (60%) patients. Concerning the overall extent of the disease at initial presentation, 3 (12%) patients had disease process in all lobes, and the disease was confined to 1 single lobe in 10 (40%) patients. The disease process was mainly peripheral in location (96%), and the lower lobes were more commonly involved (68% in the left lower lobe and 64% in the right lower lobe). Small parapneumonic effusions occurred in 1 (4%) patient. None of the patients with unifocal lesions or single-lung involvement were admitted to the ICU (P < 0.05) (in both comparisons). Subsequent follow-up of the 2 (7%) patients with normal HRCT on admission showed that they were having nonpneumonic SARS-associated coronavirus infection only and were eventually denotified from having SARS. CONCLUSIONS: HRCT is useful for early diagnosis of SARS-associated coronavirus pneumonia in patients with normal chest radiographs. HRCT findings in these patients predict potentially severe disease.