Diomidis Botsikas

PET/MR in Breast Cancer

Breast cancer is an international public health concern in which an optimal treatment plan requires a precise staging. Both MRI and PET imaging techniques have made significant progress in the last decades with constant improvements that made both modalities clinically relevant in several stages of breast cancer management and follow-up. On one hand, specific breast MRI permits high diagnostic accuracy for local tumor staging, and whole-body MRI can also be of great use in distant staging, eventually accompanied by organ-specific MRI sequences. Moreover, many different MRI sequences can be performed, including functional MRI, letting us foresee important improvements in breast cancer characterization in the future. On the contrary, (18)F-FDG-PET has a high diagnostic performance for the detection of distant metastases, and several other tracers currently under development may profoundly affect breast cancer management in the future with better determination of different types of breast cancers allowing personalized treatments. As a consequence PET/MR is a promising emerging technology, and it is foreseeable that in cases where both PET and MRI data are needed, a hybrid acquisition is justified when available. However, at this stage of deployment of such hybrid scanners in a clinical setting, more data are needed to demonstrate their added value beyond just patient comfort of having to undergo a single examination instead of two, and the higher confidence of diagnostic interpretation of these co-registered images. Optimized imaging protocols are still being developed and are prone to provide more efficient hybrid protocols with a potential improvement in diagnostic accuracy. More convincing studies with larger number of patients as well as cost-effectiveness studies are needed. This article provides insights into the current state-of-the-art of PET/MR in patients with breast cancer and gives an outlook on future developments of both imaging techniques and potential applications in the future.

Incidental adrenal lesions detected on enhanced abdominal dual-energy CT: Can the diagnostic workup be shortened by the implementation of virtual unenhanced images?

OBJECTIVE To determine whether post-processing of the data from portal-phase enhanced dual-energy CT (DECT), with or without the addition of a late enhanced phase acquisition, may enable characterization of adrenal lesions without the need for acquisition of pre-contrast images. MATERIALS AND METHODS Twenty-two patients with 24 adrenal lesions underwent unenhanced, venous and delayed phase DECT. Of these lesions, 20 were found to be adrenal adenomas, on the basis of histopathology, unenhanced attenuation values between 0 and -10 HU, or stability over at least 6 months. For all 24 lesions, true and virtual unenhanced attenuation values were measured based on the data of the portal (VNCp) and the delayed (VNCd) DECT acquisition. The absolute washout values based on the true non-contrast (TNC) and the VNCp and VNCd image series were also measured. The washout was also calculated based on the iodine concentration measured from both contrast-enhanced acquisitions. RESULTS Mean virtual unenhanced attenuation values of all lesions calculated from the portal phase images was 12.6 HU, and was 4.02 HU higher than the values based on true unenhanced images (p=0.020). Washout values calculated from virtual unenhanced attenuation based on the VNCp were also significantly different (p=0.0304) while those calculated from VNCd and from iodine concentration correlated with the corresponding values based on the true unenhanced values (p>0.999). CONCLUSIONS Our data indicate that attenuation values of adrenal adenomas based on virtual unenhanced images are significantly higher than those obtained with true unenhanced images. An incidental adrenal lesion with a virtual unenhanced attenuation lower than 10 HU can thus be safely characterized as an adenoma.

Pancreatic magnetic resonance imaging after manganese injection distinguishes type 2 diabetic and normoglycemic patients

A non-invasive method to image the mass and/or function of human pancreatic islets is needed to monitor the progression of diabetes, and the effect of therapeutic interventions. As yet, no method is available for this purpose, which could be applied to in situ human islets. Animal and in vitro studies have documented that manganese infusion could improve the magnetic resonance imaging (MRI) of the endocrine pancreas. Here, we have tested whether a similar approach could discriminate diabetic and non-diabetic patients. In vitro, human isolated islets readily incorporated manganese. In vivo, 243 manganese-enhanced magnetic resonance imaging (MEMRI) examinations were reviewed, including 41 examinations which were run on 24 patients with type 2 diabetes and 202 examinations which were run on 119 normoglycemic patients. The results show that MEMRI discriminates type 2 diabetics from non-diabetic patients, based on the signal enhancement of pancreas.

Diagnosis of Urothelial Tumors With a Dedicated Dual-Source Dual-Energy MDCT Protocol: Preliminary Results

OBJECTIVE The purpose of this study was to evaluate the diagnostic performance of a dedicated dual-source dual-energy MDCT (DECT) protocol for the detection of urothelial tumors. MATERIALS AND METHODS A DECT protocol including furosemide and split-bolus contrast injection was used in 69 consecutive patients with suspected abnormalities of the urinary system. Thirteen patients were excluded because there was no follow-up available. In 56 patients, the final diagnosis was proven with endoscopy, biopsy, or follow-up and included urothelial tumors (n = 37) in 16 patients, other urinary tract pathologies (n = 9) in eight patients, and absence of lesions of the collecting system in 32 patients. The image series consisted of a dual-energy true unenhanced series, 35-second arterial phase, and 8-minute nephrographic-excretory phase and were analyzed retrospectively. True enhancement of all detected lesions was measured. On the basis of the DECT data of the contrast-enhanced images, virtual unenhanced series were created and iodine concentration was calculated using commercially available software. The attenuation difference between virtual unenhanced and contrast-enhanced images (virtual enhancement) was measured. CT findings were compared with the final diagnosis. RESULTS Urothelial tumors were identified on 35-second series, 8-minute series, and both series combined, with sensitivity of 91.9% (95% CI, 78.1-98.2%), 83.4% (68.0-93.8%), and 97.3% (85.8-100%), respectively. Urothelial tumors showed stronger virtual enhancement (p = 0.02) and higher iodine concentration (p = 0.03) than lesions of other origin. Distinction between urothelial tumors and nontumoral lesions was possible with sensitivity of 91.9% (78.1-98.2%) when using a threshold concentration of at least 1.0 mg I/mL. CONCLUSION Dual phase DECT with virtual unenhanced imaging and iodine concentration measurement appears to be a useful diagnostic test for urothelial tumors.

A New MDCT Technique for the Detection and Anatomical Exploration of Urogenital Fistulas

OBJECTIVE We tested a new MDCT technical protocol, combining i.v. and intravesical positive contrast agent and intravaginal neutral contrast agent, that optimizes exploration of urogenital fistulas. We examined three patients (four CT examinations in total) with this technique and proved that a preexisting subtle ureterovaginal fistula that was under treatment was still present, though clinically silent. CONCLUSION The proposed MDCT examination protocol provides important information to help detect subtle urogenital fistulas.

Value of liver computed tomography with iodixanol 270, 80 kVp and iterative reconstruction

AIM To evaluate the image quality of hepatic multidetector computed tomography (MDCT) with dynamic contrast enhancement. METHODS It uses iodixanol 270 mg/mL (Visipaque 270) and 80 kVp acquisitions reconstructed with sinogram affirmed iterative reconstruction (SAFIRE(®)) in comparison with a standard MDCT protocol. Fifty-three consecutive patients with known or suspected hepatocellular carcinoma underwent 55 CT examinations, with two different four-phase CT protocols. The first group of 30 patients underwent a standard 120 kVp acquisition after injection of Iohexol 350 mg/mL (Accupaque 350(®)) and reconstructed with filtered back projection. The second group of 25 patients underwent a dual-energy CT at 80-140 kVp with iodixanol 270. The 80 kVp component of the second group was reconstructed iteratively (SAFIRE(®)-Siemens). All hyperdense and hypodense hepatic lesions ≥ 5 mm were identified with both protocols. Aorta and portal vessels/liver parenchyma contrast to noise ratio (CNR) in arterial phase, hypervascular lesion/liver parenchyma CNR in arterial phase, hypodense lesion/liver parenchyma CNR in portal and late phase were calculated in both groups. RESULTS Aorta/liver and focal lesions altogether/liver CNR were higher for the second protocol (P = 0.0078 and 0.0346). Hypervascular lesions/liver CNR was not statistically different (P = 0.86). Hypodense lesion/liver CNR in the portal phase was significantly higher for the second group (P = 0.0107). Hypodense lesion/liver CNR in the late phase was the same for both groups (P = 0.9926). CONCLUSION MDCT imaging with 80 kVp with iterative reconstruction and iodixanol 270 yields equal or even better image quality.

Colovesical fistula causing an uncommon reason for failure of computed tomography colonography: a case report

IntroductionComputed tomography colonography, or virtual colonoscopy, is a good alternative to optical colonoscopy. However, suboptimal patient preparation or colon distension may reduce the diagnostic accuracy of this imaging technique.Case presentationWe report the case of an 83-year-old Caucasian woman who presented with a five-month history of pneumaturia and fecaluria and an acute episode of macrohematuria, leading to a high clinical suspicion of a colovesical fistula. The fistula was confirmed by standard contrast-enhanced computed tomography. Optical colonoscopy was performed to exclude the presence of an underlying colonic neoplasm. Since optical colonoscopy was incomplete, computed tomography colonography was performed, but also failed due to inadequate colon distension. The insufflated air directly accumulated within the bladder via the large fistula.ConclusionsClinicians should consider colovesical fistula as a potential reason for computed tomography colonography failure.

PET/MRI in Breast Cancer

Breast cancer is the most common cancer in women worldwide, and represented more than 25% of the newly diagnosed cancer cases in women in 2016. PET/CT is recommended in the clinical workup of advanced breast cancers and in cases of breast cancer recurrence and may also be proposed in treatment monitoring. PET/MRI is a new imaging technique which is now being used clinically in different countries, and which may replace PET/CT in some selected breast cancer patients, when available. A detailed description of advantages and indications of, respectively, PET and MRI techniques taken separately in breast cancer patients is beyond the scope of the present work and has already been reviewed elsewhere by our group. We focused on the technical advantages and disadvantages of combined PET/MRI acquisitions in breast cancer patients from diagnosis to follow-up. In this chapter, we cover the specifics of PET/MRI in terms of quantification and provide a summary of the different protocols performed in breast cancer PET/MRI imaging. We will also discuss the clinical advances for patient management, the potential improvements that may occur in the future, as well as the future role that may be given to this technique.

What is the diagnostic performance of 18-FDG-PET/MR compared to PET/CT for the N- and M- staging of breast cancer?

PurposeTo compare the diagnostic performance of 18-FDG-PET/MR and PET/CT for the N- and M- staging of breast cancer.Methods and materialsTwo independent readers blinded to clinical/follow-up data reviewed PET/MR and PET/CT examinations performed for initial or recurrent breast cancer staging in 80 consecutive patients (mean age = 48 ± 12.9 years). The diagnostic confidence for lesions in the contralateral breast, axillary/internal mammary nodes, bones and other distant sites were recorded. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. The standard of reference included pathology and/or follow-up > 12 months.ResultsNine of 80 patients had bone metastases; 13/80 had other distant metastases, 44/80 had axillary, 9/80 had internal mammary and 3/80 had contralateral breast tumours. Inter-reader agreement for lesions was excellent (weighted kappa = 0.833 for PET/CT and 0.823 for PET/MR) with similar reader confidence for the two tests (ICC = 0.875). In the patient-per-patient analysis, sensitivity and specificity of PET/MRI and PET/CT were similar (p > 0.05). In the lesion-per-lesion analysis, the sensitivity of PET/MR and PET/CT for bone metastases, other metastases, axillary and internal mammary nodes, contralateral tumours and all lesions together was 0.924 and 0.6923 (p = 0.0034), 0.923 and 0.923 (p = 1), 0.854 and 0.812 (p = 0.157), 0.9 and 0.9 (p = 1), 1 and 0.25 (p = 0.083), and 0.89 and 0.77 (p = 0.0013) respectively. The corresponding specificity was 0.953 and 1 (p = 0.0081), 1 and 1 (p = 1), 0.893 and 0.92 (p = 0.257), 1 and 1 (p = 1), 0.987 and 0.99 (p = 1) and 0.96 and 0.98 (p = 0.0075) respectively.ConclusionsReader confidence, inter-reader agreement and diagnostic performance per patient were similar with PET/MR and PET/CT. However, for all lesions together, PET/MR had a superior sensitivity and lower specificity in the lesion-per-lesion analysis.Key Points• N and M breast cancer staging performance of PET/MR and PET/CT is similar per patient.• In a lesion-per-lesion analysis PET/MR is more sensitive than PET/CT especially for bone metastasis.• Readers’ diagnostic confidence is similar for both tests.

Suspicion of appendicitis in pregnant women: emergency evaluation by sonography and low-dose CT with oral contrast

ObjectivesTo evaluate non-intravenously enhanced low-dose computed tomography with oral contrast (LDCT) for the assessment of pregnant women with right lower quadrant pain, when magnetic resonance imaging (MRI) is not immediately available.MethodsOne hundred and thirty-eight consecutive pregnant women with acute abdominal pain were admitted in our emergency centre. Thirty-seven (27%) of them, with clinical suspicion of acute appendicitis, underwent abdominal ultrasonography (US). No further examination was recommended when US was positive for appendicitis, negative with low clinical suspicion or showed an alternative diagnosis which explained the clinical presentation. All other patients underwent LDCT (<2.5 mSv). Standard intravenously enhanced CT or MRI was performed when LDCT was indeterminate.ResultsEight (22%) of 37 US exams were reported normal, 25 (67%) indeterminate, 1 (3%) positive for appendicitis, 3 (8%) positive for an alternative diagnosis. LDCT was obtained in 29 (78%) patients. It was reported positive for appendicitis in 9 (31%), for alternative diagnosis in 2 (7%), normal in 13 (45%) and indeterminate in 5 (17%). Further imaging (standard CT or MRI) showed appendicitis in 2 of these 5 patients, was truly negative in 1, indeterminate in 1 and falsely positive in 1. An appendicitis was confirmed at surgery in 12 (32%) of the 37 patients. The sensitivity and the specificity of the algorithm for appendicitis were 100% (12/12) and 92% (23/25), respectively.ConclusionsThe proposed algorithm is very sensitive and specific for detection of acute appendicitis in pregnant women; it reduces the need of standard CTs when MRI is not available as second-line imaging.Key points• In pregnant women, US is limited by an important number of indeterminate results• Low-dose CT can be used after an inconclusive US for the diagnosis of appendicitis in pregnant women• An algorithm integrating US and low-dose CT is highly sensitive and specific for appendicitis in pregnant women