18F-FDG PET/CT in Waldenström associated amyloidosis.

Amyloidoisis in patients with Waldenström macroglobulinemia (WM) mostly involves the heart, peripheral nerves and kidneys. Retroperitoneal amyloidosis is a rare finding. We describe a 62-year-old man with an incidental finding of a monoclonal gammopathy and elevated inflammatory parameters. Bilateral moderately active retroperitoneal infiltration with punctiform calcifications was found on fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) imaging. Taken together, these findings are suggestive of Waldenström associated amyloidosis. Computed tomography-guided retroperitoneal biopsy confirmed the diagnosis.

Quantification of 18F-fluorodeoxyglucose uptake to detect residual nodal disease in locally advanced head and neck squamous cell carcinoma after chemoradiotherapy: results from the ECLYPS study.

BACKGROUND: The Hopkins criteria were introduced for nodal response evaluation after therapy in head and neck cancer, but its superiority over quantification is not yet confirmed. METHODS: SUVbody weight thresholds and lesion-to-background ratios were explored in a prospective multicenter study of standardized FDG-PET/CT 12 weeks after CRT in newly diagnosed locally advanced head and neck squamous cell carcinoma (LAHNSCC) patients (ECLYPS). Reference standard was histology, negative FDG-PET/CT at 12 months after treatment or ≥ 2 years of negative follow-up. Area under the receiver operator characteristics curves (AUROC) were estimated and obtained thresholds were validated in an independent cohort of HNSCC patients (n = 127). RESULTS: In ECLYPS, 124 patients were available for quantification. With a median follow-up of 20.4 months, 23 (18.5%) nodal neck recurrences were observed. A SUV70 threshold of 2.2 (AUROC = 0.89; sensitivity = 79.7%; specificity = 80.8%) was identified as optimal metric to identify nodal recurrence within 1 year after therapy. For lesion-to-background ratios, an SUV50/SUVliver threshold of 0.96 (AUROC = 0.89; sensitivity = 79.7%; specificity = 82.8%) had the best performance. Compared with Hopkins criteria (AUROC = 0.81), SUV70 and SUV50/SUVliver provided a borderline significant (p = 0.040 and p = 0.094, respectively) improvement. Validation of thresholds yielded similar AUROC values (SUV70 = 0.93, SUV50/SUVliver = 0.95), and were comparable to the Hopkins score (AUROC = 0.91; not statistically significant). CONCLUSION: FDG quantification detects nodal relapse in LAHNSCC patients. When using EARL standardized PET acquisitions and reconstruction, absolute SUV metrics (SUV70 threshold 2.2) prove robust, yet ratios (SUV50/SUVliver, threshold 0.96) may be more useful in routine clinical care. In this setting, the diagnostic value of quantification is comparable to the Hopkins criteria. TRIAL REGISTRATION: US National Library for Medicine, NCT01179360. Registered 11 August 2010, https://clinicaltrials.gov/ct2/show/NCT01179360.

Bone scan findings in erythromelalgia.

The use of hyaluronic acid nanoshells has been proposed to encapsulate prodrugs and exploit the mechanisms of interactions between living cells, like endocytes or cancer cells and hyaluronic acid, which is a natural component of the extracellular matrix. In this review we describe the potential and the limits of this promising research trend and discuss the theoretical advantages of such an engineering approach. Is it a possible scalability to increase the efficacy and biodegradability of molecules like contrast media and radiotracers especially for neuroradiology and nuclear medicine studies.

(18)F-FDG PET/CT imaging in granulomatosis with polyangiitis.

The paper gives an overview of the literature data on uptake of fluorine-18-fluorodeoxyglucose ((18)F-FDG) into the different tissue lesions which may occur in granulomatosis with polyangiitis (formerly called Wegener's syndrome). It discusses the cellular mechanisms of such (18)F-FDG uptake, which provide a basis for its interpretation in the context of (18)F-FDG positron emission tomography (PET) for inflammatory conditions.

(18)F-FDG PET imaging of granulomatosis with polyangiitis -Wegener's Syndrome.

OBJECTIVE: Granulomatosis with polyangiitis (GPA), formerly called Wegener's syndrome, is a vasculitis associated with antineutrophil cytoplasmic antibody and may occur in all ages but mostly in order adults. The organs most frequently involved are the ear, nose and throat (rhinitis, sinusitus, oral ulcers, chondritis), the lungs (nodules, sometimes cavitating, infiltrates, hilar adenopathy) and the kidneys (glomerulonephritis). As patients typically present with constitutional symptoms, the diagnosis can be challenging. We report the findings on position emission tomography/computed tomography (PET/CT) with fluorine-18-fluorodeoxyglucose ((18)F-FDG) in a patient with a limited form of GPA. CONCLUSION: None of the findings on PET are specific for GPA, but in a given clinical context, they may contribute to early diagnosis. They may guide biopsy taking, and may determine the extent of the disease. During and after treatment, PET can be used to monitor disease activity.

Incidental finding of silent appendicitis on (18)F-FDG PET/CT in a patient with small cell lung adenocarcinoma.

We report the incidental diagnosis of acute asymptomatic appendicitis on a fluorine-18-fluorodeoxyglucose positron emission tomography with computed tomography ((18)F-FDG PET/CT) performed for staging of a non small cell lung carcinoma. The patient was asymptomatic and laboratory tests were normal. The case illustrates: a) the possibility to diagnose appendicitis on (18)F-FDG PET/CT and b) the possibility of silent acute appendicitis, although this is a rare occurrence.

IgG4-related disease: The utility of (18)F-FDG PET/CT in diagnosis and treatment.

OBJECTIVE: IgG4-related disease (IgG4-RD) is a systemic mass-forming fibro-inflammatory condition which can affect nearly every organ system. Its pathophysiology remains incompletely understood, but affected tissues are characterized by a lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells which cause chronic inflammation, storiform fibrosis and phlebitis. These findings on histopathological specimens are considered the gold standard for the diagnosis. Clinical signs and symptoms largely depend upon organ involvement which can be singular or multiple, synchronous or metachronous. The organs most frequently involved are the pancreas (autoimmune pancreatitis (AIP), salivary and lacrimal glands (Mickulicz disease and sclerosing sialadenitis), biliary tree (sclerosing cholangitis or cholecystitis), retroperitoneum (retroperitoneal fibrosis), aorta (periaortic fibrosis), kidneys (interstitial nephritis) and thyroid (Riedel thyroiditis). Presentation is mostly subacute and general symptoms such as weight loss, asthenia or fever are moderate, but more prevalent in multi-organ disease. Lesions often mimic malignancy, but most respond well to steroid therapy. CONCLUSION: In this contribution we present a rare entity of IgG4-RD and discuss the utility of fluorine-18-fluorodeoxyglucose ((18)F-FDG) Positron emission tomography/computed tomography (PET/CT) in the diagnosis and treatment of this condition.

Correlative bone imaging in a case of Schnitzler's syndrome and brief review of the literature.

UNLABELLED: Schnitzler's syndrome is a rare disease characterized by a monoclonal IgM (or IgG) paraprotein, a nonpruritic urticarial skin rash, and 2 (or 3) of the following: recurrent fever, objective signs of abnormal bone remodeling, elevated CRP level or leukocytosis, and a neutrophilic infiltrate on skin biopsy. It responds well to treatment with the interleukine-1-inhibitor anakinra. We report the bone scintigraphy and MRI findings in a 45 years old man with this syndrome and compare them with data from the literature. CONCLUSION: None of the imaging findings are specific, but they lead to a differential diagnosis including infiltrative diseases (e.g. systemic mastocytosis or Erdheim-Chester disease) and dysplastic diseases (e.g. melorheostosis, Camurati-Engelmann disease or van Buchem disease). The bone scintigraphy pattern may be very suggestive of the correct diagnosis and of bone involvement in this syndrome.

Phase II Trial Assessing the Repeatability and Tumor Uptake of [68Ga]Ga-HER2 Single-Domain Antibody PET/CT in Patients with Breast Carcinoma.

Human epidermal growth factor receptor 2 (HER2) status is used for decision-making in breast carcinoma treatment. The status is obtained through immunohistochemistry or in situ hybridization. These two methods have the disadvantage of necessitating tissue sampling, which is prone to error due to tumor heterogeneity or interobserver variability. Whole-body imaging might be a solution to map HER2 expression throughout the body. Methods: Twenty patients with locally advanced or metastatic breast carcinoma (5 HER2-positive and 15 HER2-negative patients) were included in this phase II trial to assess the repeatability of uptake quantification and the extended safety of the [68Ga]Ga-NOTA-anti-HER2 single-domain antibody (sdAb). The tracer was injected, followed by a PET/CT scan at 90 min. Within 8 d, the procedure was repeated. Blood samples were taken for antidrug antibody (ADA) assessment and liquid biopsies. On available tissues, immunohistochemistry, in situ hybridization, and mass spectrometry were performed to determine the correlation of HER2 status with uptake values measured on PET. If relevant preexisting [18F]FDG PET/CT images were available (performed as standard of care), a comparison was made. Results: With a repeatability coefficient of 21.8%, this imaging technique was repeatable. No clear correlation between PET/CT uptake values and pathology could be established, as even patients with low levels of HER2 expression showed moderate to high uptake. Comparison with [18F]FDG PET/CT in 16 patients demonstrated that in 7 patients, [68Ga]Ga-NOTA-anti-HER2 shows interlesional heterogeneity within the same patient, and [18F]FDG uptake did not show the same heterogeneous uptake in all patients. In some patients, the extent of disease was clearer with the [68Ga]Ga-NOTA-anti-HER2-sdAb. Sixteen adverse events were reported but all without a clear relationship to the tracer. Three patients with preexisting ADAs did not show adverse reactions. No new ADAs developed. Conclusion: [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT imaging shows similar repeatability to [18F]FDG. It is safe for clinical use. There is tracer uptake in cancer lesions, even in patients previously determined to be HER2-low or -negative. The tracer shows potential in the assessment of interlesional heterogeneity of HER2 expression. In a subset of patients, [68Ga]Ga-NOTA-anti-HER2-sdAb uptake was seen in lesions with no or low [18F]FDG uptake. These findings support further clinical development of [68Ga]Ga-NOTA-anti-HER2-sdAb as a PET/CT tracer in breast cancer patients.

Preoperative imaging for hyperparathyroidism often takes upper parathyroid adenomas for lower adenomas.

We retrospectively evaluated how accurately preoperative imaging localizes parathyroid adenoma in superior versus inferior parathyroids. Over 6 years, 104 patients with primary hyperparathyroidism underwent parathyroid surgery in a single centre. Of these, 103 underwent ultrasound, 97 [99mTc]pertechnetate/MIBI SPECT/CT and 30 [18F]fluorocholine (FCH) PET/CT. One patient with a unilateral double adenoma was excluded from the analysis. Surgical findings with histopathologic confirmation of adenoma were used as the standard. Ultrasound misjudged 5 of 48 detected lower adenomas as upper, but 14 of 29 upper adenomas as lower (error rate 10 vs 48%, p = 0.0002). The corresponding error rates for [99mTc]pertechnetate/MIBI SPECT/CT were 3 versus 55% (p = 0.000014), and for [18F]FCH PET/CT 17 versus 36% (p = 0.26). Our results suggest that about half of the superior parathyroid adenomas which are detected, are erroneously assigned to the inferior position by both ultrasound and SPECT/CT imaging whereas the opposite mistake is significantly less frequent with ultrasound and SPECT/CT.

Parathyroid adenoma apoplexy mimicking a thyroid bleeding cyst: a seemingly innocent condition that can be life-threatening.

Summary: Primary hyperparathyroidism most commonly presents with hypercalcaemia. Rarely, parathyroid apoplexy or haemorrhage mimicking a thyroid bleeding cyst is the first presentation of a parathyroid adenoma. A woman presented with a sudden-onset painful 'goitre'. Ultrasound showed a cystic nodule located posterior to rather than in the right thyroid lobe, suggesting parathyroid adenoma bleeding. Biochemistry showed mild primary hyperparathyroidism. 99mTc-pertechnetate/sestamibi showed no uptake in the nodule, which was interpreted as a cold thyroid nodule. 18F-fluorocholine PET/CT showed uptake in the nodule, suggestive of a parathyroid adenoma. Persistent mild primary hyperparathyroidism complicated by nephrolithiasis and osteopenia favoured parathyroidectomy over a wait-and-see approach. The patient was referred for parathyroidectomy along with right thyroid lobectomy. Pathology showed an adenoma, with an eccentrically located cystic structure filled with red blood cells surrounded by a thickened fibrous capsule. In conclusion, cervical pain/haemorrhage with hypercalcaemia points to the diagnosis of parathyroid apoplexy, mimicking a thyroid bleeding cyst. Workup with ultrasound and, if available, 18F-choline PET/CT allows for timely surgery, minimizing the risk of recurrent and severe bleeding. Learning points: A bleeding cyst may be located posterior to rather than in the thyroid, suggesting a parathyroid haemorrhage. Neck pain and/or haemorrhage along with primary hyperparathyroidism point to parathyroid apoplexy. A two-step presentation has been described, with a first phase of local symptoms to be followed by visible and possibly life-threatening compressing bleeding. Therefore, an expedited workup is needed, allowing for timely surgery.

Should we screen for coronary artery disease in asymptomatic chronic dialysis patients?

The hemodialysis population is characterized by a high prevalence of 'asymptomatic' coronary artery disease (CAD), which should be interpreted differently from asymptomatic disease in the general population. A hemodynamically significant stenosis may not become clinically apparent owing to impaired exercise tolerance and autonomic neuropathy. The continuous presence of silent ischemia may cause heart failure, arrhythmias, and sudden death. Whether revascularization of an asymptomatic dialysis patient improves outcome remains a moot point, although several observational studies and one small RCT suggest a benefit. It can therefore be defended to screen asymptomatic dialysis patients for CAD. A number of noninvasive screening tests are available, but none has proved equally practical and reliable in the dialysis population as in the general population. Myocardial perfusion scintigraphy (MPS) before and after a pharmacological stress such as dipyridamole can reveal both ischemia and myocardial scarring. When compared with coronary angiography, low sensitivities were reported and attributed to impaired vasodilation to dipyridamole in dialysis patients. A more likely explanation is that not every anatomical stenosis will lead to impaired coronary blood flow on MPS. Numerous studies have shown an incremental prognostic value of dipyridamole-MPS over clinical data for prediction of adverse cardiac events, in some studies even over coronary angiography. Pending the availability of high-quality evidence, in our opinion asymptomatic dialysis patients could undergo dipyridamole-MPS, followed by coronary angiography in case of an abnormal scan. This combined physiological and anatomical evaluation of the coronary circulation allows us to determine which coronary stenosis is clinically relevant and therefore should be revascularized.

Retrospective real-life study on preoperative imaging for minimally invasive parathyroidectomy in primary hyperparathyroidism.

The objective of this study was to retrospectively evaluate preoperative imaging modalities for localization of parathyroid adenomas with a view to enable minimally invasive parathyroidectomy and in particular, to consider the contribution of 18F-fluorocholine-PET/CT. 104 patients with primary hyperparathyroidism, who underwent parathyroid surgery in a single centre during a 6-year period were included. Of these, 103 underwent ultrasound, 97 99mTc-Pertechnetate/SestaMIBI-SPECT, 20 MRI and 30 18F-fluorocholine-PET/CT. Based on surgical findings, sensitivities and specificities for correct lateralisation in orthotopic locations were: for ultrasound 0.75 (0.65-0.83) and 0.89 (0.81-0.94), for 99mTc-MIBI-SPECT 0.57 (0.46-0.67) and 0.97 (0.91-0.99), for MRI 0.60 (0.36-0.81) and 0.83 (0.59-0.96) and for 18F-fluorocholine-PET/CT 0.90 (0.73-0.98) and 0.90 (0.73-0.98). Correctly lateralized adenomas were significantly larger than those not found with ultrasound (p = 0.03) and SPECT (p = 0.002). Pre-operative PTH-levels were higher in single adenomas detected by scintigraphy than in those not (p = 0.02). 64 patients could be treated with a minimally invasive procedure. Cure after parathyroidectomy was obtained in 94% of patients. 18F-Fluorocholine-PET/CT could be shown to be a highly accurate modality to localize parathyroid adenomas preoperatively, obviating the need for total exploration in the majority of patients in whom ultrasound and scintigraphic results are discordant or both negative.

Dual time point imaging in locally advanced head and neck cancer to assess residual nodal disease after chemoradiotherapy.

BACKGROUND: FDG-PET/CT has a high negative predictive value to detect residual nodal disease in patients with locally advanced squamous cell head and neck cancer after completing concurrent chemoradiotherapy (CCRT). However, the positive predictive value remains suboptimal due to inflammation after radiotherapy, generating unnecessary further investigations and possibly even surgery. We report the results of a preplanned secondary end point of the ECLYPS study regarding the potential advantages of dual time point FDG-PET/CT imaging (DTPI) in this setting. Standardized dedicated head and neck FDG-PET/CT images were obtained 12 weeks after CCRT at 60 and 120 min after tracer administration. We performed a semiquantitative assessment of lymph nodes, and the retention index (RI) was explored to optimize diagnostic performance. The reference standard was histology, negative FDG-PET/CT at 1 year, or > 2 years of clinical follow-up. The time-dependent area under the receiver operator characteristics (AUROC) curves was calculated. RESULTS: In total, 102 subjects were eligible for analysis. SUV values increased in malignant nodes (median SUV1 = 2.6 vs. SUV2 = 2.7; P = 0.04) but not in benign nodes (median SUV1 = 1.8 vs. SUV2 = 1.7; P = 0.28). In benign nodes, RI was negative although highly variable (median RI = - 2.6; IQR 21.2), while in malignant nodes RI was positive (median RI = 12.3; IQR 37.2) and significantly higher (P = 0.018) compared to benign nodes. A combined threshold (SUV1 ≥ 2.2 + RI ≥ 3%) significantly reduced the amount of false-positive cases by 53% (P = 0.02) resulting in an increased specificity (90.8% vs. 80.5%) and PPV (52.9% vs. 37.0%), while sensitivity (60.0% vs. 66.7%) and NPV remained comparably high (92.9% vs. 93.3%). However, AUROC, as overall measure of benefit in diagnostic accuracy, did not significantly improve (P = 0.62). In HPV-related disease (n = 32), there was no significant difference between SUV1, SUV2, and RI in malignant and benign nodes, yet this subgroup was small. CONCLUSIONS: DTPI did not improve the overall diagnostic accuracy of FDG-PET/CT to detect residual disease 12 weeks after chemoradiation. Due to differences in tracer kinetics between malignant and benign nodes, DTPI improved the specificity, but at the expense of a loss in sensitivity, albeit minimal. Since false negatives at the 12 weeks PET/CT are mainly due to minimal residual disease, DTPI is not able to significantly improve sensitivity, but repeat scanning at a later time (e.g. after 12 months) could possibly solve this problem. Further study is required in HPV-associated disease.

Trends in diagnosis, referral, red flag onset, patient profiles and natural outcome of de novo cardiac amyloidosis and their multidisciplinary implications.

BACKGROUND: Cardiac amyloidosis (CA) is often overlooked or misdiagnosed. Effects of growing disease awareness, diagnostic ameliorations and novel treatment options on CA diagnosis and management are scarcely reported. OBJECTIVE: To report trends in diagnosis, referral routes, clinical presentation, early onset diagnostic red flags and outcome in de novo CA subjects. METHODS: An unselected cohort of 139 de novo CA patients over an 8-year period in a tertiary referral hospital was recruited. RESULTS: Transthyretin (ATTR, 82%, n = 114) was the most common CA form; Light-chain (AL, 15%, n = 21) and secondary (AA, 3%, n = 4) are less prevalent. Increased awareness over time led to a marked ATTR diagnostic surge, steep non-invasive diagnostic approach increment and increased nuclear medicine and external cardiologist referrals (all p < 0.001). A total of 41% (n = 57/139) of patients were referred by non-cardiology specialist disciplines. Specific referral to rule out CA (24-36%) and diagnostic time lag from symptom onset (9 ± 12 to 8 ± 14 months), however, did not improve (all p > 0.050). Multiple early red flag events preceded CA diagnose several years in ATTR: Left ventricular hypertrophy (LVH, 60%, 4.9 ± 4.3 y), heart failure (54%, 2.5 ± 3.5 y), atrial fibrillation (47%, 5.9 ± 6.7 y), bilateral carpal tunnel syndrome (43%, 9.5 ± 5.7 y) and spinal stenosis (40%, 7.4 ± 6.5 y). LVH ≥ 12 mm was absent in 11% ATTR (n = 13/114) and 5% AL (n = 1/21) patients. Hypertension was common in both ATTR (n = 70/114, 62%) and AL (n = 10/21, 48%). 56% (n = 78/139) of CA presented with heart failure. Cumulative 1 and 5-year mortality of 10%/66%, 40%/52% and 75%/75% for ATTR, AL, and AA, respectively, remains high. CONCLUSIONS: Although CA diagnostic uptake and referral improve, specialist-specific disease and diagnostic red flag ignorance result in non-timely diagnosis and unfavourable outcome.

Quantitative Effect of Metal Artefact Reduction on CT-based attenuation correction in FDG PET/CT in patients with hip prosthesis.

BACKGROUND: Metal artefact reduction (MAR) techniques still are in limited use in positron emission tomography/computed tomography (PET/CT). This study aimed to investigate the effect of Smart MAR on quantitative PET analysis in the vicinity of hip prostheses. MATERIALS AND METHODS: Activities were measured on PET/CT images in 6 sources with tenfold activity concentration contrast to background, attached to the head, neck and the major trochanter of a human cadaveric femur, and in the same sources in similar locations after a hip prosthesis (titanium cup, ceramic head, chrome-cobalt stem) had been inserted into the femur. Measurements were compared between PET attenuation corrected using either conventional or MAR CT. In 38 patients harbouring 49 hip prostheses, standardized uptake values (SUV) in 6 periprosthetic regions and the bladder were compared between PET attenuation corrected with either conventional or MAR CT. RESULTS: Using conventional CT, measured activity decreased with 2 to 13% when the prosthesis was inserted. Use of MAR CT increased measured activity by up to 11% compared with conventional CT and reduced the relative difference with the reference values to under 5% in all sources. In all regions, to the exception of the prosthesis shaft, SUVmean increased significantly (p < 0.001) by use of MAR CT. Median (interquartile range) percentual increases of SUVmean were 1.4 (0.0-4.2), 4.0 (1.8-7.8), 7.8 (4.1-12.4), 1.5 (0.0-3.2), 1.4 (0.8-2.8) in acetabulum, lateral neck, medial neck, lateral diaphysis and medial diaphysis, respectively. Except for the shaft, the coefficient of variation did not increase significantly. Except for the erratic changes in the prosthesis shaft, decreases in SUVmean were rare and small. Bladder SUVmean increased by 0.9% in patients with unilateral prosthesis and by 4.1% in patients with bilateral prosthesis. CONCLUSIONS: In a realistic hip prosthesis phantom, Smart MAR restores quantitative accuracy by recovering counts in underestimated sources. In patient studies, Smart MAR increases SUV in all areas surrounding the prosthesis, most markedly in the femoral neck region. This proves that underestimation of activity in the PET image is the most prevalent effect due to metal artefacts in the CT image in patients with hip prostheses. Smart MAR increases SUV in the urinary bladder, indicating effects at a distance from the prosthesis.

Digital tomosynthesis in the detection of urolithiasis: Diagnostic performance and dosimetry compared with digital radiography with MDCT as the reference standard.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of digital tomosynthesis in comparison with digital radiography in the detection of urinary stones with MDCT as the reference standard. SUBJECTS AND METHODS: Fifty consecutively enrolled patients (32 men, 18 women; mean age, 51.5 years; range, 19-83 years) referred for unenhanced MDCT of the abdomen with suspicion of urinary stones also underwent digital tomosynthesis and digital radiography (anteroposterior and bladder inlet views). Images from all examinations were randomly read by three blinded radiologists. The mean effective doses for digital tomosynthesis, digital radiography, and low- and high-dose MDCT were measured on a male phantom. Free-response receiver operating characteristics and receiver operating characteristics analyses were used to compare the diagnostic performance of digital radiography with that of digital tomosynthesis. RESULTS: Both types of analysis showed significantly better performance of tomosynthesis over digital radiography for all urinary stones (p < 0.05). No such improvement was found for ureteral stones. The gain in sensitivity with tomosynthesis was largest for stones between 2 and 5 mm in diameter. The mean effective dose was 0.5 mSv for digital radiography, 0.85 mSv for tomosynthesis, 2.5 mSv for low-dose MDCT, and 12.6 mSv for high-dose MDCT. CONCLUSION: Use of digital tomosynthesis of the abdomen results in improved detection of urinary stones in general over digital radiography with only a slight increase in effective dose. Use of tomosynthesis, however, was not associated with major improvement in the diagnosis of ureteral stones. The technique has potential as an alternative imaging technique in the detection and follow-up of urinary stones.

Utility of pelvic bone SPET in imaging urinary bladder filling defects in urinary bladder carcinoma.

Urinary bladder carcinoma sometimes can be recognized on bone scans as a filling defect in the bladder. This paper illustrates in three patients that the filling defects of urinary bladder on pelvic bone single photon emission tomography (SPET) scans in cases of bladder carcinoma correspond to those on computerized tomography (CT). In one patient, the void sign could only be discerned on the SPET images, but not on the planar images. In the same patient, the filling defect was almost entirely surrounded by urinary activity, suggesting an intrinsic bladder lesion. The differential diagnosis of filling defects is presented. The above findings are compared to other related studies, although we have found no similar cases in the literature. When compared with CT, pelvic SPET is more sensitive than planar imaging in recognizing bladder filling defects on bone scans and may allow distinguish between intrinsic and extrinsic bladder lesions.

Corpus Cavernosum Abscess Diagnosed on FDG PET/CT.

The utility of PET in septicemia for showing its source and possible metastatic infection has been demonstrated. We describe the diagnosis on PET/CT of a spontaneous corpus cavernosum abscess in a 64-year-old man presenting with Streptococcus constellatus septicemia, in whom the clinical diagnosis had been elusive for 10 days.

Comparison of the prognostic value of dipyridamole and dobutamine myocardial perfusion scintigraphy in hemodialysis patients.

Screening for coronary artery disease (CAD) in hemodialysis patients is hampered by contraindications and/or limitations of the available techniques in this population. Myocardial perfusion scintigraphy (MPS) using dipyridamole has been considered inaccurate due to abnormally high basal levels of adenosine in uremia that could blunt the vasodilatory response. Since dobutamine may be more reliable, we directly compared the two in patients on hemodialysis. We performed MPS at rest and after separate dipyridamole or dobutamine stress in 121 chronic hemodialysis patients. More numerous, larger, and more intense reversible lesions were induced with dobutamine than with dipyridamole, mainly in the anteroseptal segments. Reversibility with dipyridamole but not dobutamine MPS was independently and strongly related with mortality associated with CAD and with fatal and non-fatal CAD. We hypothesize that the chronotropic action of dobutamine induced alterations of wall motion, leading to spurious perfusion defects, not unlike artifacts seen with left bundle branch block. Our study shows that even though dobutamine induced more pronounced myocardial ischemia than dipyridamole in chronic hemodialysis patients, dipyridamole MPS more accurately identifies patients at high risk for subsequent cardiac death or non-fatal CAD than dobutamine.