Occipital horn syndrome in a woman: skeletal radiological findings.

Ehlers-Danlos type IX syndrome, also called occipital horn syndrome (OHS), is a milder and rare form of Menkes disease where the patient reaches adulthood. As an X-linked disease, it typically occurs in male subjects, while female subjects are usually healthy carriers. OHS is mainly characterized by connective tissue disorders and slightly subnormal intelligence or signs of autonomic dysfunction are the only apparent neurological abnormalities, in connection with molecular defects in copper metabolism. Our purpose is to report on radiological skeletal findings that may be incidental or investigated when OHS is suspected and to underline the possible involvement and expression in the female. Moreover, the impact of skeletal findings is also highlighted in the prevention of serious complications of the disease.

Accuracy of MRI/MRSI-based transrectal ultrasound biopsy in peripheral and transition zones of the prostate gland in patients with prior negative biopsy.

The purpose of the study was to evaluate the accuracy of transrectal ultrasound biopsy (TRUS-biopsy) performed on regions with abnormal MRI and/or MRSI for both the transition (TZ) and the peripheral (PZ) zones in patients with suspected prostate cancer with prior negative biopsy, and to analyze the relationship between MRSI and histopathological findings. MRI and MRSI were performed in 54 patients (mean age: 63.9 years, mean PSA value: 11.4 ng/mL) and the ability of MRI/MRSI-directed TRUS biopsy was evaluated. A three-point score system was used for both techniques to distinguish healthy from malignant regions. Descriptive statistics and ROC analyses were performed to evaluate the accuracy and the best cut-off in the three-point score system. Twenty-two out of 54 patients presented cancer at MRI/MRSI-directed TRUS biopsy, nine presented cancer only in PZ, eight both in PZ and TZ, and five exclusively in TZ. On a patient basis the highest accuracy was obtained by assigning malignancy on a positive finding with MRSI and MRI even though it was not significantly greater than that obtained using MRI alone (area under the ROC curve, AUC: 0.723 vs 0.676). On a regional (n = 648) basis the best accuracy was also obtained by considering positive both MRSI and MRI for PZ (0.768) and TZ (0.822). MRSI was false positive in 11.9% of the regions. Twenty-eight percent of cores with prostatitis were false positive findings on MRSI, whereas only 2.7% of benign prostatic hyperplasia was false positive. In conclusion, the accuracy of MRI/MRSI-directed biopsies in localization of prostate cancer is good in patient (0.723) and region analyses (0.768). The combination of both MRI and MRSI results makes TRUS-biopsy more accurate, particularly in the TZ (0.822) for patients with prior negative biopsies. Histopathological analysis showed that the main limitation of MRSI is the percentage of false positive findings due to prostatitis.

Computerized tomography virtual endoscopy in evaluation of upper urinary tract tumors: initial experience.

PURPOSE: To assess the usefulness of CT virtual endoscopy (VE) as an integration of CT-urography, for the detection of upper urinary tract tumor in patients with hematuria. MATERIALS AND METHODS: Fourteen patients with hematuria and high risk of transitional cell carcinoma of the upper urinary tract underwent urinary cytology, ultrasonography, excretory urography, cystoscopy, CT-urography with VE, and optical ureteroscopy. The CT urograms and VE were correlated with the pathological findings of surgical specimen (6/14) and cytological examination of ureteroscopy biopsy (8/14). RESULTS: VE revealed three renal pelvic and one ureteral tumors, not producing further information did not detected at CT-urography. In two patients VE showed findings strongly indicative of malignancies, not noticed at CT-urography: ureteroscopic biopsy revealed an advanced dysplastic lesion and a malignancy, confirmed at surgery. In one patient VE was questionable (narrowing of the distal ureter) and ureteroscopic biopsy revealed an inflammation. Finally, VE diagnosed a fibrosis of the lumbar ureteral tract, confirmed at ureteroscopic biopsy. In other six patients, VE and ureteroscopy did not find abnormalities. CONCLUSION: VE should be useful as an integration of CT-urography for a complete evaluation of the upper urinary tract in patients with suspected tumor, limiting the need for fiberoptic ureteroscopic examination.

Histological verification of positive positron emission tomography findings in the follow-up of patients with mediastinal lymphoma.

BACKGROUND AND OBJECTIVES: Follow-ups of patients with mediastinal lymphoma are not accurate if they rely on computed tomography (CT). Positron emission tomography (PET) has been suggested to be useful in several lymphoma settings, such as initial staging, evaluation of residual masses after therapy, and assessment of response early in the course of treatment. The aim of this retrospective study was to verify the reliability of positive PET scans of the mediastinum in following up patients with mediastinal lymphoma, using histological findings as a comparison. DESIGN AND METHODS: From January 2002 to July 2005, 151 patients with mediastinal lymphoma (57 with Hodgkin's disease [HD] and 94 with aggressive non-Hodgkin's lymphoma [NHL]) were followed-up after the end of front-line treatment. Patients with a positive PET scan of the mediastinum underwent CT scanning and surgical biopsy. RESULTS: In 30 (21 HD and 9 NHL) out of 151 patients (20%) a suspicion of lymphoma relapse was raised based on positive mediastinal PET scanning. Histology confirmed this suspicion in 17 (10 HD and 7 NHL) out of 30 patients (57%), whereas either benign (9 fibrosis, 3 sarcoid-like granulomatosis) or unrelated neoplastic conditions (1 thymoma) were demonstrated in the remaining 13 patients (43%). SUVmax was significantly higher among patients who had signs of relapse (17 true positive cases) than among those who stayed in remission (13 false positive cases), the median values being 5.95 (range, 3.5-26.9) and 2.90 (range, 1.4-3.3), respectively (p=0.01). INTERPRETATION AND CONCLUSIONS: We suggest that a positive PET scan of the mediastinum of a patient being followed-up for a mediastinal lymphoma should not be considered sufficient for diagnostic purposes in view of its lack of discrimination. Histological confirmation can safely be carried out with various biopsy techniques, the choice of which should be made on the basis of the findings of the clinical and imaging studies of the individual case.

Detection and localization of prostate cancer: correlation of (11)C-choline PET/CT with histopathologic step-section analysis.

UNLABELLED: This study evaluated the potential usefulness of (11)C-choline PET/CT for detection and localization of tumors within the prostate. We used the results of step-section histopathologic examination as the standard of reference. METHODS: The results were analyzed on a sextant basis. We reviewed the results of the (11)C-choline PET/CT scans of 36 patients with prostate cancer and of 5 control subjects with bladder cancer. All patients underwent (11)C-choline PET/CT and, subsequently, radical prostatectomy with lymph node dissection within 1 mo. (11)C-Choline PET/CT scans were obtained 5-10 min after intravenous injection of 370-555 MBq of (11)C-choline. Images were reviewed visually and semiquantitatively using maximum SUV and tumor-to-background ratio. RESULTS: On a sextant basis, histopathologic analysis detected cancer foci in 143 of 216 sextants; high-grade prostate intraepithelial neoplasm foci were detected in 89 of 216 sextants (in 59 sextants in association with carcinoma, in 30 sextants alone), acute prostatitis was detected in 7 of 216 sextants (in 3 sextants in association with carcinoma, in 4 sextants alone), and 39 of 216 sextants were normal. PET/CT demonstrated focal (11)C-choline uptake in 108 sextants (94 of which involved tumor), and 108 sextants showed no abnormal (11)C-choline uptake (49 of which were false negative). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT were 66%, 81%, 71%, 87%, and 55%, respectively. In the 5 control subjects, high-grade prostate intraepithelial neoplasm was detected at histologic examination in 16 of 30 sextants. PET/CT showed increased (11)C-choline uptake in 5 of 16 sextants. CONCLUSION: This study demonstrated the feasibility of using (11)C-choline PET/CT to identify cancer foci within the prostate. However, we also found that (11)C-choline PET/CT has a relative high rate of false-negative results on a sextant basis and that prostatic disorders other than cancer may accumulate (11)C-choline. Therefore, our data do not support the routine use of PET/CT with (11)C-choline as a first-line screening procedure for prostate cancer in men at high risk.

Potential pitfalls of 18F-FDG PET in a large series of patients treated for malignant lymphoma: prevalence and scan interpretation.

OBJECTIVE: To evaluate the prevalence and scan interpretation criteria useful in identifying non-tumoural F-FDG focal uptakes (potential pitfalls) in patients who had been previously treated for a malignant lymphoma studied by positron emission tomography (PET). MATERIALS: Nine hundred and ninety-six consecutive PET scans obtained in 706 patients with malignant lymphoma were reviewed. All patients had been previously treated by first-line chemo-radiotherapy, plus surgery when required, and were then studied by FDG PET to investigate suspected recurrence at doubtful or inconclusive conventional radiological imaging (ultrasound, computed tomography, magnetic resonance imaging). PET was obtained with patients in the fasted condition and after i.v. injection of 370 MBq of F-FDG; imaging was acquired 60-90 min later. In patients with focal FDG uptake the final diagnosis was reached on the basis of histological findings or long-term follow-up. RESULTS: Thirty-one of 134 PET scans (23.1%) showing focal FDG uptake were diagnosed as non-tumoural radiotracer uptake, related to the presence of brown fat in seven cases, thymic hyperplasia in five, muscles contraction in four, lymph node unspecific inflammation in four, mediastinal/pulmonary unspecific inflammation in four, gastritis in two, colitis in two, bacterial abscess in one, lactating breast in one, and herpes zoster in one. Each of the above cited situations has been reported in the literature, generally in the form of sporadic reports, as a potential cause of misinterpretation (false positive) in reading a PET scan with the potential for incorrect patient management. An accurate diagnosis in these patients was important for the following therapeutic decision making. CONCLUSIONS: In the whole series of patients with treated malignant lymphoma, the prevalence of non-tumoural FDG focal uptake during follow-up was relatively low (3.1%); conversely, it was relatively high when considering the sub-group of 'positive' PET only (23.1%). The importance of knowing these situations in order to avoid misinterpretation in reading PET scans needs to be emphasized. In this light, an accurate patient's history and a skilful nuclear medicine physician are very important factors. For the same purpose, it is reasonable to think that the use of hybrid PET/CT tomographs could also play an important role in helping to identify non-tumoural FDG focal uptake.

18F-FDG PET early after radiotherapy in lymphoma patients.

OBJECTIVE: The aim of this study was to evaluate the rate of postactinic inflammatory alterations that could lead to false-positive results in FDG-PET images, in a group of lymphoma patients studied with positron emission tomography (PET) early after the end of radiation therapy. MATERIALS AND METHODS: Sixteen (16) consecutive patients were referred to our center for malignant lymphoma; 14 of 16 patients had a mediastinal bulky mass at diagnosis. Each patient underwent chemotherapy and then radiotherapy (RT): for clinical reasons, shortly after RT (range, 25-56 days; mean, 38.7 days) a FDG PET scan was required to evaluate the effect of therapy. We intravenously injected 370 MBq of 18F-FDG, and after 60-90 minutes we recorded images. RESULTS: Despite a relatively short time after RT, there was no pathological tracer uptake in 13 of 16 patients. In 3 cases, a mild increase in FDG uptake was observed, but no findings which would lead to a false-positive diagnosis. In 2 of 3 cases, postactinic pneumopathy was diagnosed (PET scan performed 51 and 52 days after RT); while in 1 patient, soft-tissue inflammation was present (PET scan performed 42 days after RT). CONCLUSION: Our data indicates that the rate of postactinic PET inflammatory alterations in lymphoma patients is not very high and appear to be not strictly linked to the elapsed time since the end of RT treatment.

Somatostatin receptor scintigraphy for bronchial carcinoid follow-up.

PURPOSE: Somatostatin receptor scintigraphy (SRS) has been used to diagnose bronchial carcinoids (BC) and is a valuable tool for accurate staging of BC. The aim of this study was to evaluate the role of SRS in restaging BC and following patients after treatment. METHODS: Thirty-one patients (18 male, 13 female) with confirmed BC who were referred during the last 7 years were included. Patients were examined via chest radiograph (12 studies), chest or abdominal computed tomography (CT; 28 scans), chest magnetic resonance imaging (2 scans), and liver ultrasound (5 scans). RESULTS: Overall, in 22 patients (71%), SRS confirmed the data obtained by other diagnostic procedures (16 negative and 6 positive findings). In 6 patients, SRS showed focal lesions not previously demonstrated. In 2 patients, SRS resolved uncertain findings of CT. In 1 patient, SRS showed fewer lesions compared with CT. In 8 of 31 patients, important diagnostic information obtained by SRS was not revealed by any other imaging procedure. CONCLUSION: Our results indicate that SRS is a reliable, noninvasive method that could be considered the principal follow-up procedure in patients with BC.

Accuracy, reproducibility and repeatability of ultrasonography in the assessment of abdominal adiposity.

RATIONALE AND OBJECTIVES: Despite improvements in the methods used in body composition analysis, some goals remain far from clinical practice. Among them, the most important is the quantification of intra-abdominal adipose tissue. Fat distribution is a key point in the assessment of cardiovascular and metabolic risk status. The aim of this study was to define the accuracy, reproducibility, and repeatability of ultrasonography in the evaluation of abdominal adiposity. MATERIALS AND METHODS: Twenty-six nonobese patients (group A) who underwent computed tomographic (CT) abdominal imaging and 29 obese patients (group B) were enrolled. Patients from both groups were independently evaluated using ultrasound by three radiologists; computed tomography-like conditions were reproduced, and six main parameters of subcutaneous and internal adiposity were measured (as well as three derived indexes) with both linear and convex probes. In group A, the same measurements were also obtained on CT images. Time spent for every ultrasound session was recorded. Results were analyzed using Lin's concordance correlation (ρ), intraclass correlation, and linear regression analysis (and analysis of variance). RESULTS: Three patients were excluded from group A after CT scans because of technical problems. Mesenteric fat thickness did not show significant correlations and reliability. Strong correlations between ultrasound and CT measurements were observed for all other visceral and subcutaneous parameters (ρ = 0.85-0.96). Intraobserver and interobserver agreement was excellent in both groups (repeatability: ρ = 0.83-0.99 for group A, ρ = 0.90-0.99 for group B; reproducibility: intraclass correlation coefficient = 0.90-0.99 for groups A and B). The mean time spent was 95 ± 21 seconds for group A (mean body mass index, 27.4 ± 2.4 kg/m(2)) and 129 ± 33 seconds for group B (mean body mass index, 37.3 ± 11.9 kg/m(2)). CONCLUSIONS: Ultrasound is accurate, reproducible, and fast in the analysis of abdominal adiposity. It offers a regional, easy, and close-at-hand evaluation of subcutaneous and visceral fat compartments. This should be taken into consideration when clinical routine examinations are performed or to evaluate patients with specific metabolic diseases before and after treatment.

Latest developments in imaging of bladder cancer.

Despite the development of optic cystoscopy and new imaging techniques, the diagnostic process for bladder cancer is still a matter of debate and imaging management remains a work in progress. This article focuses on imaging of bladder cancer, from cornerstone modalities to new proposals and ideas. The discussion aims to point out and to stress whether techniques are sufficient in the diagnosis, staging and treatment evaluation of bladder cancer, as well as during the follow-up. Advantages, pitfalls and limits of every imaging method used or proposed will be analyzed, not to find 'the truth', but to allow the best optimization of the diagnostic tools available today in clinical practice.

Incidental lung nodules on CT examinations of the abdomen: prevalence and reporting rates in the PACS era.

OBJECTIVES: To retrospectively evaluate prevalence, reporting rates and clinical implications of incidental pulmonary nodules detected in multidetector computed tomography (MDCT) abdominal studies. MATERIALS AND METHODS: Abdominal MDCT studies of 243 consecutive patients, 94 of whom had a history of cancer, were evaluated. Lung bases included in the scan were reviewed on a PACS workstation with different window settings and post-processing techniques. Nodules were classified according to their density (calcified, solid noncalcified, non-solid, part-solid) and size (<4mm; 4-6mm; 6-8mm; >8mm). The study findings were compared with the corresponding radiologic reports. Previous of following CT studies, when available from the PACS, were also reviewed to evaluate changes in number and size of the detected nodules. RESULTS: An average of 8.2 cm of lung parenchyma was imaged in each patient. 213 noncalcified nodules (NCNs) were identified in 95 patients (39.1%) but only 8 patients (8.4%) had it mentioned in the final report. Comparison CT studies were available for 44 out of the 95 positive patients showing disappearance of the nodules in 2 cases, no interval change in 26 and progression in size and/or number in 16 patients, in whom a final diagnosis of metastasis or primary lung cancers was achieved. CONCLUSION: Radiologists tend to overlook lung portions on abdominal CT studies. Underreporting may affect patient care and have medico-legal implications since images are permanently stored in digital format on PACS and CD-ROMs. Management of the discovered nodules should be tailored to the clinical situation of the patient, and particular care should be reserved to patients with oncologic history.

Prostate cancer: sextant localization with MR imaging, MR spectroscopy, and 11C-choline PET/CT.

PURPOSE: To retrospectively compare sensitivity and specificity of magnetic resonance (MR) imaging, three-dimensional (3D) MR spectroscopy, combined MR imaging and 3D MR spectroscopy, and carbon 11 (11C)-choline positron emission tomography (PET)/computed tomography (CT) for intraprostatic tumor sextant localization, with histologic findings as reference standard. MATERIALS AND METHODS: The local ethics committee on human research provided approval and a waiver of informed consent for the retrospective study. MR imaging, 3D MR spectroscopy, and 11C-choline PET/CT results were retrospectively reviewed in 26 men with biopsy-proved prostate cancer (mean age, 64 years; range, 51-75 years) who underwent radical prostatectomy. Cancer was identified as areas of nodular low signal intensity on T2-weighted MR images. At 3D MR spectroscopy, choline-plus-creatine-to-citrate and choline-to-creatine ratios were used to distinguish healthy from malignant voxels. At PET/CT, focal uptake was visually assessed, and maximum standardized uptake values (SUVs) were recorded. Agreement between 3D MR spectroscopic and PET/CT results was calculated, and ability of maximum SUV to help localize cancer was assessed with receiver operating characteristic analysis. Significant differences between positive and negative sextants with respect to mean maximum SUV were calculated with a paired t test. RESULTS: Sensitivity, specificity, and accuracy were, respectively, 55%, 86%, and 67% at PET/CT; 54%, 75%, and 61% at MR imaging; and 81%, 67%, and 76% at 3D MR spectroscopy. The highest sensitivity was obtained when either 3D MR spectroscopic or MR imaging results were positive (88%) at the expense of specificity (53%), while the highest specificity was obtained when results with both techniques were positive (90%) at the expense of sensitivity (48%). Concordance between 3D MR spectroscopic and PET/CT findings was slight (kappa=0.139). CONCLUSION: In localizing cancer within the prostate, comparable specificity was obtained with either 3D MR spectroscopy and MR imaging or PET/CT; however, PET/CT had lower sensitivity relative to 3D MR spectroscopy alone or combined with MR imaging.

Role of 18F-FDG PET/CT in the assessment of bone involvement in newly diagnosed multiple myeloma: preliminary results.

PURPOSE: Multiple myeloma (MM) is a malignant B cell and plasma cell disorder which involves the skeleton in more than 80% of patients at diagnosis. The aim of this study was to compare whole-body X-ray (WBXR), MRI and (18)F-FDG PET/CT in patients with MM. METHODS: The study population comprised 28 newly diagnosed MM patients. Findings of (18)F-FDG PET/CT were compared with those of WBXR and MRI with regard to the number and site of lesions detected. RESULTS: Comparing (18)F-FDG PET/CT and WBXR, it was found that in 16/28 pts (57%) (18)F-FDG PET/CT detected more lesions, all of which were located in the skeleton. Nine of these 16 patients had a completely negative WBXR survey. In 12/28 pts (43%) the two methods yielded equivalent findings. Comparing (18)F-FDG PET/CT and MRI, it was found that in 7/28 pts (25%), (18)F-FDG PET/CT detected more lytic bone lesions, all of which were located outside the field of view of MRI (bone lesions in six cases and a soft tissue lesion in one). In 14/28 pts (50%), (18)F-FDG PET/CT and MRI detected the same number of lesions in the spine and pelvis, while in 7/28 pts (25%) MRI detected an infiltrative pattern in the spine whereas (18)F-FDG PET/CT was negative. CONCLUSION: (18)F-FDG PET/CT appears to be more sensitive than WBXR for the detection of small lytic bone lesions, whereas it has the same sensitivity as MRI in detecting bone disease of the spine and pelvis. On the other hand, MRI may be superior to (18)F-FDG PET/CT in diagnosing an infiltrative pattern in the spine. Therefore, careful evaluation of MM bone disease at diagnosis should include both MRI of the spine and (18)F-FDG PET/CT.

PET and PET-CT. State of the art and future prospects.

Fluoro-deoxyglucose positron emission tomography (FDG PET) enables the in vivo study of tissue metabolism, and thus is able to identify malignant tumours as hypermetabolic lesions by an increase in tracer uptake. Many papers have demonstrated both the relevant impact of FDG PET on staging of many cancers and the superior accuracy of the technique compared with conventional diagnostic methods for pre-treatment evaluation, therapy response evaluation and relapse identification. In particular PET was found useful in identifying lymph nodal and metastatic spread, thus altering patient management in more than 30% of cases. PET images, however, provide limited anatomical data, which in regions such as the head and neck, mediastinum and pelvic cavity is a significant drawback. The exact localization of lesions may also be difficult in some cases on the basis of PET images alone. The introduction of combined PET-computed tomography (PET-CT) scanners enables the almost simultaneous acquisition of transmission and emission images, thus obtaining optimal fusion images in a very short time. PET-CT fusion images enable lesions to be located, reducing false positive studies and increasing accuracy; the overall duration of the examination may also be reduced. On the basis of both literature data and our experience we established the clinical indications when PET-CT may be particularly useful, in comparison with PET alone. It should also be underlined that the use of PET-CT is almost mandatory for new tracers such as 11C-choline and 11C-methionine; these new tracers may be applied for studying tumours not assessable with FDG, such as prostate cancer. In conclusion PET-CT is at present the most advanced method for metabolic imaging, and is capable of precisely localizing and assessing tumours; fusion images reduce false positive and inconclusive studies, thus increasing diagnostic accuracy.

18F-FDG PET in malignant lymphoma: significance of positive findings.

PURPOSE: The aim of this study was to evaluate the significance of increased uptake of 18F-fluorodeoxyglucose (FDG) in patients with malignant lymphoma (ML) studied by positron emission tomography (PET). METHODS: A total of 1,120 consecutive scans carried out in 848 patients were reviewed; all patients had a diagnosis of ML [574 non-Hodgkin's lymphoma (NHL) and 274 Hodgkin's disease (HD)] and were studied at completion of therapy, for suspected recurrence or during follow-up. PET was carried out after intravenous injection of 370 MBq of 18F-FDG; images were recorded after 60-90 min. Patients were selected whose reports indicated areas of increased FDG uptake. PET findings were considered positive for lymphomatous localisation when uptake occurred at sites of previous disease, in asymmetrical lymph nodes or in nodes unlikely to be affected by inflammation (mediastinal, except for hilar, and abdominal). PET findings were adjudged negative for neoplastic localisations in the following instances: physiological uptake (urinary, muscular, thymic or gastrointestinal in patients without MALT), symmetrical nodal uptake, uptake in lesions unrelated to lymphoma that had already been identified by other imaging methods at the time of PET scan, uptake at sites atypical for lymphoma, very low uptake and non-focal uptake. PET findings were compared with the results of other diagnostic procedures (including CT and ultrasound), biopsy findings and follow-up data. RESULTS: Overall, 354 scans (in 256 patients) showed increased FDG uptake (244 scans in NHL and 110 in HD): in 286 cases, FDG uptake was considered pathological and indicative of ML, in 41 cases the findings were described as uncertain or equivocal and in 37 cases, FDG uptake was considered unrelated to ML (in ten scans, concurrent findings of abnormal FDG uptake attributed to ML and uptake assigned to other causes were obtained) . Of the 286 patients with positive PET findings, 274 (95.8%) were found to have residual or recurrent ML (i.e. true positives). Four of the 41 patients with inconclusive findings turned out to have ML, while in 13 patients, pathological processes other than ML could be identified as the cause of FDG uptake. ML was excluded in all patients with findings reported as non-pathological (100% true-negative rate). Therefore, the false-positive rate in our series was about 5%. The main cause of increased FDG uptake mimicking ML was inflammation. CONCLUSION: Our data confirm that 18F-FDG-PET has very high but not absolute specificity for ML. As already suggested, increased FDG uptake may also be observed in patients without active disease; in most cases, however, non-pathological FDG accumulation is properly identified. Less frequently, inconclusive scans are encountered; these cases are usually caused by inflammation, which subsequently resolves.

Thoracic manifestations of the less common collagen diseases. A pictorial essay.

Systemic autoimmune diseases include different forms of vasculitides and collagen diseases. Among collagen diseases, the rarer entities include: Sjögren syndrome, dermatopolymyositis, ankylosing spondylitis, relapsing polychondritis and mixed connective tissue disorders. The diagnosis of these entities requires an integrated multidisciplinary approach. The radiological findings of collagen diseases are well known; however, the introduction of HRCT studies provides additional information and enable an early diagnosis. The more common thoracic manifestations of collagen diseases include interstitial pneumonia (usual, nonspecific and lymphocytic), bronchiolitis obliterans organizing pneumonia (BOOP), airway diseases (bronchiectasis, obliterative and constrictive bronchiolitis, follicular bronchiolitis), pleural abnormalities, diaphragmatic dysfunction, apical fibrosis. The aim of this pictorial essay is to present the main radiological and HRCT patterns related to the less common collagen diseases.

Ground-glass opacity: interpretation of high resolution CT findings.

Ground-glass opacity (GGO) is a common finding on high resolution CT, characterised by areas of hazy increased attenuation of the lung with preservation of bronchial and vascular margins; it is not to be confused with consolidation, in which bronchovascular structures are obscured. It correlates with several pathogenic processes, such as like partial filling of air spaces, inflammatory or fibrotic interstitial thickening, increased capillary blood volume. Infiltrative GGO can representing either interstitial or alveolar processes. GGO is a nonspecific finding; however, the correlation with any of the associated CT findings (nodular lesions, consolidation, septal thickening, fibrosis, vessels or airway calibre alterations, air trapping), and clinical data is helpful in narrowing the range of diagnostic possibilities, or even in suggesting a specific diagnosis. GGO can indicate a potentially treatable disease, help guide the type and location of biopsy and evaluate the effectiveness of therapy. This review discusses the types of lung disease associated with GGO, and the differential diagnosis between GGO caused by infiltrative processes and the mosaic patterns of lung attenuation caused by primary vascular diseases or airway abnormalities. This distinction can be made by evaluating the vessel calibre and air trapping on expiratory scans.